vi/vi.c

/* vi: set sw=4 ts=4: */
/*
 * tiny vi.c: A small 'vi' clone
 * Copyright (C) 2000, 2001 Sterling Huxley <sterling@europa.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//'vi' is a text editor. More specifically, it is the One True
//text editor <grin>. It does, however, have a rather steep
//learning curve. If you are not already comfortable with 'vi'
//you may wish to use something else.

#include <rtthread.h>
#include <optparse.h>
#include "vi_utils.h"

/* This struct is deliberately not defined. */
/* See docs/keep_data_small.txt */
struct globals;
/* '*const' ptr makes gcc optimize code much better.
 * Magic prevents ptr_to_globals from going into rodata.
 * If you want to assign a value, use SET_PTR_TO_GLOBALS(x) */
struct globals *ptr_to_globals;

/* Should be after libbb.h: on some systems regex.h needs sys/types.h: */
#if ENABLE_FEATURE_VI_REGEX_SEARCH
# include <regex.h>
#endif

/* the CRASHME code is unmaintained, and doesn't currently build */
#define ENABLE_FEATURE_VI_CRASHME 0


#if ENABLE_LOCALE_SUPPORT

#if ENABLE_FEATURE_VI_8BIT
//FIXME: this does not work properly for Unicode anyway
# define Isprint(c) (isprint)(c)
#else
# define Isprint(c) isprint_asciionly(c)
#endif

#else

/* 0x9b is Meta-ESC */
#if ENABLE_FEATURE_VI_8BIT
# define Isprint(c) ((unsigned char)(c) >= ' ' && (c) != 0x7f && (unsigned char)(c) != 0x9b)
#else
# define Isprint(c) ((unsigned char)(c) >= ' ' && (unsigned char)(c) < 0x7f)
#endif

#endif

enum {
    MAX_TABSTOP = 32, // sanity limit
    // User input len. Need not be extra big.
    // Lines in file being edited *can* be bigger than this.
    MAX_INPUT_LEN = 128,
    // Sanity limits. We have only one buffer of this size.
    MAX_SCR_COLS = CONFIG_FEATURE_VI_MAX_LEN,
    MAX_SCR_ROWS = CONFIG_FEATURE_VI_MAX_LEN,
};

// VT102 ESC sequences.
// See "Xterm Control Sequences"
// http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
#define ESC "\033"
// Inverse/Normal text
#define ESC_BOLD_TEXT ESC"[7m"
#define ESC_NORM_TEXT ESC"[m"
// Bell
#define ESC_BELL "\007"
// Clear-to-end-of-line
#define ESC_CLEAR2EOL ESC"[K"
// Clear-to-end-of-screen.
// (We use default param here.
// Full sequence is "ESC [ <num> J",
// <num> is 0/1/2 = "erase below/above/all".)
#define ESC_CLEAR2EOS          ESC"[J"
// Cursor to given coordinate (1,1: top left)
#define ESC_SET_CURSOR_POS     ESC"[%u;%uH"
#define ESC_SET_CURSOR_TOPLEFT ESC"[H"
//UNUSED
//// Cursor up and down
//#define ESC_CURSOR_UP   ESC"[A"
//#define ESC_CURSOR_DOWN "\n"

#if ENABLE_FEATURE_VI_DOT_CMD || ENABLE_FEATURE_VI_YANKMARK
static const char modifying_cmds[] ALIGN1 = "aAcCdDiIJoOpPrRs""xX<>~";
#endif

enum {
    YANKONLY = FALSE,
    YANKDEL = TRUE,
    FORWARD = 1,    // code depends on "1"  for array index
    BACK = -1,  // code depends on "-1" for array index
    LIMITED = 0,    // char_search() only current line
    FULL = 1,   // char_search() to the end/beginning of entire text
    PARTIAL = 0,    // buffer contains partial line
    WHOLE = 1,  // buffer contains whole lines
    MULTI = 2,  // buffer may include newlines

    S_BEFORE_WS = 1,    // used in skip_thing() for moving "dot"
    S_TO_WS = 2,        // used in skip_thing() for moving "dot"
    S_OVER_WS = 3,      // used in skip_thing() for moving "dot"
    S_END_PUNCT = 4,    // used in skip_thing() for moving "dot"
    S_END_ALNUM = 5,    // used in skip_thing() for moving "dot"

    C_END = -1, // cursor is at end of line due to '$' command
};


/* vi.c expects chars to be unsigned. */
/* busybox build system provides that, but it's better */
/* to audit and fix the source */
struct globals {
    /* many references - keep near the top of globals */
    char *text, *end;       // pointers to the user data in memory
    char *dot;              // where all the action takes place
    int text_size;      // size of the allocated buffer

    // the rest
    smallint vi_setops;     // set by setops()
#define VI_AUTOINDENT (1 << 0)
#define VI_ERR_METHOD (1 << 1)
#define VI_IGNORECASE (1 << 2)
#define VI_SHOWMATCH  (1 << 3)
#define VI_TABSTOP    (1 << 4)
#define autoindent (vi_setops & VI_AUTOINDENT)
#define err_method (vi_setops & VI_ERR_METHOD) // indicate error with beep or flash
#define ignorecase (vi_setops & VI_IGNORECASE)
#define showmatch  (vi_setops & VI_SHOWMATCH )
// order of constants and strings must match
#define OPTS_STR \
        "ai\0""autoindent\0" \
        "fl\0""flash\0" \
        "ic\0""ignorecase\0" \
        "sm\0""showmatch\0" \
        "ts\0""tabstop\0"

#if ENABLE_FEATURE_VI_READONLY
    smallint readonly_mode;
#define SET_READONLY_FILE(flags)        ((flags) |= 0x01)
#define SET_READONLY_MODE(flags)        ((flags) |= 0x02)
#define UNSET_READONLY_FILE(flags)      ((flags) &= 0xfe)
#else
#define SET_READONLY_FILE(flags)        ((void)0)
#define SET_READONLY_MODE(flags)        ((void)0)
#define UNSET_READONLY_FILE(flags)      ((void)0)
#endif

    smallint editing;        // >0 while we are editing a file
                             // [code audit says "can be 0, 1 or 2 only"]
    smallint cmd_mode;       // 0=command  1=insert 2=replace
    int modified_count;      // buffer contents changed if !0
    int last_modified_count; // = -1;
    int cmdline_filecnt;     // how many file names on cmd line
    int cmdcnt;              // repetition count
    unsigned rows, columns;  // the terminal screen is this size
#if ENABLE_FEATURE_VI_ASK_TERMINAL
    int get_rowcol_error;
#endif
    int crow, ccol;          // cursor is on Crow x Ccol
    int offset;              // chars scrolled off the screen to the left
    int have_status_msg;     // is default edit status needed?
                             // [don't make smallint!]
    int last_status_cksum;   // hash of current status line
    char *current_filename;
    char *screenbegin;       // index into text[], of top line on the screen
    char *screen;            // pointer to the virtual screen buffer
    int screensize;          //            and its size
    int tabstop;
    int last_search_char;    // last char searched for (int because of Unicode)
    smallint last_search_cmd;    // command used to invoke last char search
#if ENABLE_FEATURE_VI_CRASHME
    char last_input_char;    // last char read from user
#endif

#if ENABLE_FEATURE_VI_DOT_CMD
    smallint adding2q;   // are we currently adding user input to q
    int lmc_len;             // length of last_modifying_cmd
    char *ioq, *ioq_start;   // pointer to string for get_one_char to "read"
#endif
#if ENABLE_FEATURE_VI_SEARCH
    char *last_search_pattern; // last pattern from a '/' or '?' search
#endif

    /* former statics */
#if ENABLE_FEATURE_VI_YANKMARK
    char *edit_file__cur_line;
#endif
    int refresh__old_offset;
    int format_edit_status__tot;

    /* a few references only */
#if ENABLE_FEATURE_VI_YANKMARK
    smalluint YDreg;//,Ureg;// default delete register and orig line for "U"
#define Ureg 27
    char *reg[28];          // named register a-z, "D", and "U" 0-25,26,27
    char regtype[28];       // buffer type: WHOLE, MULTI or PARTIAL
    char *mark[28];         // user marks points somewhere in text[]-  a-z and previous context ''
    char *context_start, *context_end;
#endif
#if ENABLE_FEATURE_VI_USE_SIGNALS
    sigjmp_buf restart;     // int_handler() jumps to location remembered here
#endif
#ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
    struct termios term_orig; // remember what the cooked mode was
#endif
    int cindex;               // saved character index for up/down motion
    smallint keep_index;      // retain saved character index
#if ENABLE_FEATURE_VI_COLON
    char *initial_cmds[3];  // currently 2 entries, NULL terminated
#endif
    // Should be just enough to hold a key sequence,
    // but CRASHME mode uses it as generated command buffer too
#if ENABLE_FEATURE_VI_CRASHME
    char readbuffer[128];
#else
    char readbuffer[KEYCODE_BUFFER_SIZE];
#endif
#define STATUS_BUFFER_LEN  200
    char status_buffer[STATUS_BUFFER_LEN]; // messages to the user
#if ENABLE_FEATURE_VI_DOT_CMD
    char last_modifying_cmd[MAX_INPUT_LEN]; // last modifying cmd for "."
#endif
    char get_input_line__buf[MAX_INPUT_LEN]; /* former static */

    char scr_out_buf[MAX_SCR_COLS + MAX_TABSTOP * 2];
#if ENABLE_FEATURE_VI_UNDO
// undo_push() operations
#define UNDO_INS         0
#define UNDO_DEL         1
#define UNDO_INS_CHAIN   2
#define UNDO_DEL_CHAIN   3
// UNDO_*_QUEUED must be equal to UNDO_xxx ORed with UNDO_QUEUED_FLAG
#define UNDO_QUEUED_FLAG 4
#define UNDO_INS_QUEUED  4
#define UNDO_DEL_QUEUED  5
#define UNDO_USE_SPOS   32
#define UNDO_EMPTY      64
// Pass-through flags for functions that can be undone
#define NO_UNDO          0
#define ALLOW_UNDO       1
#define ALLOW_UNDO_CHAIN 2
# if ENABLE_FEATURE_VI_UNDO_QUEUE
#define ALLOW_UNDO_QUEUED 3
    char undo_queue_state;
    int undo_q;
    char *undo_queue_spos;  // Start position of queued operation
    char undo_queue[CONFIG_FEATURE_VI_UNDO_QUEUE_MAX];
# else
// If undo queuing disabled, don't invoke the missing queue logic
#define ALLOW_UNDO_QUEUED 1
# endif

    struct undo_object {
        struct undo_object *prev;   // Linking back avoids list traversal (LIFO)
        int start;      // Offset where the data should be restored/deleted
        int length;     // total data size
        uint8_t u_type;     // 0=deleted, 1=inserted, 2=swapped
        char undo_text[1];  // text that was deleted (if deletion)
    } *undo_stack_tail;
#endif /* ENABLE_FEATURE_VI_UNDO */

};
#define G (*ptr_to_globals)
#define text           (G.text          )
#define text_size      (G.text_size     )
#define end            (G.end           )
#define dot            (G.dot           )
#define reg            (G.reg           )

#define vi_setops               (G.vi_setops          )
#define editing                 (G.editing            )
#define cmd_mode                (G.cmd_mode           )
#define modified_count          (G.modified_count     )
#define last_modified_count     (G.last_modified_count)
#define cmdline_filecnt         (G.cmdline_filecnt    )
#define cmdcnt                  (G.cmdcnt             )
#define rows                    (G.rows               )
#define columns                 (G.columns            )
#define crow                    (G.crow               )
#define ccol                    (G.ccol               )
#define offset                  (G.offset             )
#define status_buffer           (G.status_buffer      )
#define have_status_msg         (G.have_status_msg    )
#define last_status_cksum       (G.last_status_cksum  )
#define current_filename        (G.current_filename   )
#define screen                  (G.screen             )
#define screensize              (G.screensize         )
#define screenbegin             (G.screenbegin        )
#define tabstop                 (G.tabstop            )
#define last_search_char        (G.last_search_char   )
#define last_search_cmd         (G.last_search_cmd    )
#if ENABLE_FEATURE_VI_CRASHME
#define last_input_char         (G.last_input_char    )
#endif
#if ENABLE_FEATURE_VI_READONLY
#define readonly_mode           (G.readonly_mode      )
#else
#define readonly_mode           0
#endif
#define adding2q                (G.adding2q           )
#define lmc_len                 (G.lmc_len            )
#define ioq                     (G.ioq                )
#define ioq_start               (G.ioq_start          )
#define last_search_pattern     (G.last_search_pattern)

#define edit_file__cur_line     (G.edit_file__cur_line)
#define refresh__old_offset     (G.refresh__old_offset)
#define format_edit_status__tot (G.format_edit_status__tot)

#define YDreg          (G.YDreg         )
//#define Ureg           (G.Ureg          )
#define regtype        (G.regtype )
#define mark           (G.mark          )
#define context_start  (G.context_start )
#define context_end    (G.context_end   )
#define restart        (G.restart       )
#ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
#define term_orig      (G.term_orig     )
#endif
#define cindex         (G.cindex        )
#define keep_index     (G.keep_index    )
#define initial_cmds   (G.initial_cmds  )
#define readbuffer     (G.readbuffer    )
#define scr_out_buf    (G.scr_out_buf   )
#define last_modifying_cmd  (G.last_modifying_cmd )
#define get_input_line__buf (G.get_input_line__buf)

#if ENABLE_FEATURE_VI_UNDO
#define undo_stack_tail  (G.undo_stack_tail )
# if ENABLE_FEATURE_VI_UNDO_QUEUE
#define undo_queue_state (G.undo_queue_state)
#define undo_q           (G.undo_q          )
#define undo_queue       (G.undo_queue      )
#define undo_queue_spos  (G.undo_queue_spos )
# endif
#endif

#define INIT_G() do { \
    SET_PTR_TO_GLOBALS(vi_zalloc(sizeof(G))); \
    last_modified_count = -1; \
    /* "" but has space for 2 chars: */ \
    IF_FEATURE_VI_SEARCH(last_search_pattern = vi_zalloc(2);) \
} while (0)

static void edit_file(char *);  // edit one file
static void do_cmd(int);    // execute a command
static int next_tabstop(int);
static void sync_cursor(char *, int *, int *);  // synchronize the screen cursor to dot
static char *begin_line(char *);    // return pointer to cur line B-o-l
static char *end_line(char *);  // return pointer to cur line E-o-l
static char *prev_line(char *); // return pointer to prev line B-o-l
static char *next_line(char *); // return pointer to next line B-o-l
static char *end_screen(void);  // get pointer to last char on screen
static int count_lines(char *, char *); // count line from start to stop
static char *find_line(int);    // find begining of line #li
static char *move_to_col(char *, int);  // move "p" to column l
static void dot_left(void); // move dot left- dont leave line
static void dot_right(void);    // move dot right- dont leave line
static void dot_begin(void);    // move dot to B-o-l
static void dot_end(void);  // move dot to E-o-l
static void dot_next(void); // move dot to next line B-o-l
static void dot_prev(void); // move dot to prev line B-o-l
static void dot_scroll(int, int);   // move the screen up or down
static void dot_skip_over_ws(void); // move dot pat WS
static char *bound_dot(char *); // make sure  text[0] <= P < "end"
static void new_screen(int, int);  // malloc virtual screen memory
#if !ENABLE_FEATURE_VI_UNDO
#define char_insert(a,b,c) char_insert(a,b)
#endif
static char *char_insert(char *, char, int);    // insert the char c at 'p'
// might reallocate text[]! use p += stupid_insert(p, ...),
// and be careful to not use pointers into potentially freed text[]!
static uintptr_t stupid_insert(char *, char);   // stupidly insert the char c at 'p'
static int find_range(char **, char **, char);  // return pointers for an object
static int st_test(char *, int, int, char *);   // helper for skip_thing()
static char *skip_thing(char *, int, int, int); // skip some object
static char *find_pair(char *, const char); // find matching pair ()  []  {}
#if !ENABLE_FEATURE_VI_UNDO
#define text_hole_delete(a,b,c) text_hole_delete(a,b)
#endif
static char *text_hole_delete(char *, char *, int); // at "p", delete a 'size' byte hole
// might reallocate text[]! use p += text_hole_make(p, ...),
// and be careful to not use pointers into potentially freed text[]!
static uintptr_t text_hole_make(char *, int);   // at "p", make a 'size' byte hole
#if !ENABLE_FEATURE_VI_UNDO
#define yank_delete(a,b,c,d,e) yank_delete(a,b,c,d)
#endif
static char *yank_delete(char *, char *, int, int, int);    // yank text[] into register then delete
static void show_help(void);    // display some help info
static void rawmode(void);  // set "raw" mode on tty
static void cookmode(void); // return to "cooked" mode on tty
// sleep for 'h' 1/100 seconds, return 1/0 if stdin is (ready for read)/(not ready)
static int mysleep(int);
static int get_one_char(void);  // read 1 char from stdin
// file_insert might reallocate text[]!
static int file_insert(const char *, char *, int);
static int file_write(char *, char *, char *);
static void screen_erase(void);
static void go_bottom_and_clear_to_eol(void);
static void standout_start(void);   // send "start reverse video" sequence
static void standout_end(void); // send "end reverse video" sequence
static void flash(int);     // flash the terminal screen
static void show_status_line(void); // put a message on the bottom line
static void status_line(const char *, ...);     // print to status buf
static void status_line_bold(const char *, ...);
static void status_line_bold_errno(const char *fn);
static void not_implemented(const char *); // display "Not implemented" message
static int format_edit_status(void);    // format file status on status line
static void redraw(int);    // force a full screen refresh
static char* format_line(char* /*, int*/);
static void refresh(int);   // update the terminal from screen[]

static void indicate_error(void);       // use flash or beep to indicate error
static void Hit_Return(void);

#if ENABLE_FEATURE_VI_SEARCH
static char *char_search(char *, const char *, int); // search for pattern starting at p
#endif
#if ENABLE_FEATURE_VI_COLON
static char *get_one_address(char *, int *);    // get colon addr, if present
static char *get_address(char *, int *, int *); // get two colon addrs, if present
#endif
static void colon(char *);  // execute the "colon" mode cmds
#if ENABLE_FEATURE_VI_USE_SIGNALS
static void winch_handler(int); // catch window size changes
static void tstp_handler(int);  // catch ctrl-Z
static void int_handler(int);   // catch ctrl-C
#endif
#if ENABLE_FEATURE_VI_DOT_CMD
static void start_new_cmd_q(char);  // new queue for command
static void end_cmd_q(void);    // stop saving input chars
#else
#define end_cmd_q() ((void)0)
#endif
#if ENABLE_FEATURE_VI_SETOPTS
static void showmatching(char *);   // show the matching pair ()  []  {}
#endif
#if ENABLE_FEATURE_VI_YANKMARK || (ENABLE_FEATURE_VI_COLON && ENABLE_FEATURE_VI_SEARCH) || ENABLE_FEATURE_VI_CRASHME
// might reallocate text[]! use p += string_insert(p, ...),
// and be careful to not use pointers into potentially freed text[]!
# if !ENABLE_FEATURE_VI_UNDO
#define string_insert(a,b,c) string_insert(a,b)
# endif
static uintptr_t string_insert(char *, const char *, int);  // insert the string at 'p'
#endif
#if ENABLE_FEATURE_VI_YANKMARK
static char *text_yank(char *, char *, int, int);    // save copy of "p" into a register
static char what_reg(void);     // what is letter of current YDreg
static void check_context(char);    // remember context for '' command
#endif
#if ENABLE_FEATURE_VI_UNDO
static void flush_undo_data(void);
static void undo_push(char *, unsigned, unsigned char); // push an operation on the undo stack
static void undo_push_insert(char *, int, int); // convenience function
static void undo_pop(void); // undo the last operation
# if ENABLE_FEATURE_VI_UNDO_QUEUE
static void undo_queue_commit(void); // flush any queued objects to the undo stack
# else
# define undo_queue_commit() ((void)0)
# endif
#else
#define flush_undo_data()   ((void)0)
#define undo_queue_commit() ((void)0)
#endif

#if ENABLE_FEATURE_VI_CRASHME
static void crash_dummy();
static void crash_test();
static int crashme = 0;
#endif

static struct optparse options;

static void write1(const char *out)
{
    fputs(out, stdout);
}

static int vi_main(int argc, char **argv)
{
    int c;
    char *file_name;

    if(vi_mem_init() == 0) // RT-Thread team added
    {
        rt_kprintf("vi initialization failed.\r\n");
        return -1;
    }

    INIT_G();

#if ENABLE_FEATURE_VI_UNDO
    /* undo_stack_tail = NULL; - already is */
#if ENABLE_FEATURE_VI_UNDO_QUEUE
    undo_queue_state = UNDO_EMPTY;
    /* undo_q = 0; - already is  */
#endif
#endif

#if ENABLE_FEATURE_VI_CRASHME
    srand((long) getpid());
#endif
#ifdef NO_SUCH_APPLET_YET
    // if we aren't "vi", we are "view"
    if (ENABLE_FEATURE_VI_READONLY && applet_name[2]) {
        SET_READONLY_MODE(readonly_mode);
    }
#endif

    // 0: all of our options are disabled by default in vim
    //vi_setops = 0;
    //  1-  process EXINIT variable from environment
    //  2-  if EXINIT is unset process $HOME/.exrc file (not inplemented yet)
    //  3-  process command line args
#if ENABLE_FEATURE_VI_COLON
    {
        char *p = getenv("EXINIT");
        if (p && *p)
            initial_cmds[0] = vi_strndup(p, MAX_INPUT_LEN);
    }
#endif
    optparse_init(&options, argv); // RT-Thread team added
    while ((c = optparse(&options, "hCRH" IF_FEATURE_VI_COLON("c:"))) != -1) {
        switch (c) {
#if ENABLE_FEATURE_VI_CRASHME
        case 'C':
            crashme = 1;
            break;
#endif
#if ENABLE_FEATURE_VI_READONLY
        case 'R':       // Read-only flag
            SET_READONLY_MODE(readonly_mode);
            break;
#endif
#if ENABLE_FEATURE_VI_COLON
        case 'c':       // cmd line vi command
            if (*options.optarg)
                initial_cmds[initial_cmds[0] != NULL] = vi_strndup(options.optarg, MAX_INPUT_LEN);
            break;
#endif
        case 'H':
            show_help();
            // fall through
        default:
            printf("Usage: vi [FILE]\n"); /*bb_show_usage();*/
            return 1;
        }
    }

    options.argv += options.optind;
    cmdline_filecnt = argc - options.optind;

    // "Save cursor, use alternate screen buffer, clear screen"
    write1("\033[?1049h");
    // This is the main file handling loop
    options.optind = 0;
    file_name = optparse_arg(&options);
    while (1) {
        edit_file(file_name); // might be NULL on 1st iteration
        // NB: optind can be changed by ":next" and ":rewind" commands
        options.optind++;
        file_name = optparse_arg(&options);
        if (options.optind >= cmdline_filecnt)
            break;
    }
    // "Use normal screen buffer, restore cursor"
    write1("\033[?1049l");

    /* RT-Thread team added */
    vi_free(text);
    vi_free(screen);
    vi_free(current_filename);
#if ENABLE_FEATURE_VI_DOT_CMD
    vi_free(ioq_start);
#endif
#if ENABLE_FEATURE_VI_SEARCH
    vi_free(last_search_pattern);
#endif
    vi_free(ptr_to_globals);
    fflush_all();

    vi_mem_release();
    return 0;
}
MSH_CMD_EXPORT_ALIAS(vi_main, vi, a screen-oriented text editor);

/* read text from file or create an empty buf */
/* will also update current_filename */
static int init_text_buffer(char *fn)
{
    int rc;

    flush_undo_data();
    modified_count = 0;
    last_modified_count = -1;
#if ENABLE_FEATURE_VI_YANKMARK
    /* init the marks */
    rt_memset(mark, 0, sizeof(mark));
#endif

    /* allocate/reallocate text buffer */
    vi_free(text);
    text_size = 10240;
    screenbegin = dot = end = text = vi_zalloc(text_size);

    if (fn != current_filename) {
        vi_free(current_filename);
        current_filename = vi_strdup(fn);
    }
    rc = file_insert(fn, text, 1);
    if (rc < 0) {
        // file doesnt exist. Start empty buf with dummy line
        char_insert(text, '\n', NO_UNDO);
    }
    return rc;
}

#if ENABLE_FEATURE_VI_WIN_RESIZE
static int query_screen_dimensions(void)
{
    int err = get_terminal_width_height(STDIN_FILENO, &columns, &rows);
    if (rows > MAX_SCR_ROWS)
        rows = MAX_SCR_ROWS;
    if (columns > MAX_SCR_COLS)
        columns = MAX_SCR_COLS;
    return err;
}
#else
static int query_screen_dimensions(void) { return 0; }
#endif

static void edit_file(char *fn)
{
#if ENABLE_FEATURE_VI_YANKMARK
#define cur_line edit_file__cur_line
#endif
    int c;
#if ENABLE_FEATURE_VI_USE_SIGNALS
    int sig;
#endif

    editing = 1;    // 0 = exit, 1 = one file, 2 = multiple files
    rawmode();
    rows = 24;
    columns = 80;
    IF_FEATURE_VI_ASK_TERMINAL(G.get_rowcol_error =) query_screen_dimensions();
#if ENABLE_FEATURE_VI_ASK_TERMINAL
    if (G.get_rowcol_error /* TODO? && no input on stdin */) {
        uint64_t k;
        write1("\033[999;999H" "\033[6n");
        fflush_all();
        k = read_key(STDIN_FILENO, readbuffer, /*timeout_ms:*/ 100);
        if ((int32_t)k == KEYCODE_CURSOR_POS) {
            uint32_t rc = (k >> 32);
            columns = (rc & 0x7fff);
            if (columns > MAX_SCR_COLS)
                columns = MAX_SCR_COLS;
            rows = ((rc >> 16) & 0x7fff);
            if (rows > MAX_SCR_ROWS)
                rows = MAX_SCR_ROWS;
        }
    }
#endif
    new_screen(rows, columns);  // get memory for virtual screen
    init_text_buffer(fn);

#if ENABLE_FEATURE_VI_YANKMARK
    YDreg = 26;         // default Yank/Delete reg
//  Ureg = 27; - const // hold orig line for "U" cmd
    mark[26] = mark[27] = text; // init "previous context"
#endif

    last_search_char = '\0';
#if ENABLE_FEATURE_VI_CRASHME
    last_input_char = '\0';
#endif
    crow = 0;
    ccol = 0;

#if ENABLE_FEATURE_VI_USE_SIGNALS
    signal(SIGWINCH, winch_handler);
    signal(SIGTSTP, tstp_handler);
    sig = sigsetjmp(restart, 1);
    if (sig != 0) {
        screenbegin = dot = text;
    }
    // int_handler() can jump to "restart",
    // must install handler *after* initializing "restart"
    signal(SIGINT, int_handler);
#endif

    cmd_mode = 0;       // 0=command  1=insert  2='R'eplace
    cmdcnt = 0;
    tabstop = 4;
    offset = 0;         // no horizontal offset
    c = '\0';
#if ENABLE_FEATURE_VI_DOT_CMD
    vi_free(ioq_start);
    ioq_start = NULL;
    lmc_len = 0;
    adding2q = 0;
#endif

#if ENABLE_FEATURE_VI_COLON
    {
        char *p, *q;
        int n = 0;

        while ((p = initial_cmds[n]) != NULL) {
            do {
                q = p;
                p = strchr(q, '\n');
                if (p)
                    while (*p == '\n')
                        *p++ = '\0';
                if (*q)
                    colon(q);
            } while (p);
            vi_free(initial_cmds[n]);
            initial_cmds[n] = NULL;
            n++;
        }
    }
#endif
    redraw(FALSE);          // dont force every col re-draw
    //------This is the main Vi cmd handling loop -----------------------
    while (editing > 0) {
#if ENABLE_FEATURE_VI_CRASHME
        if (crashme > 0) {
            if ((end - text) > 1) {
                crash_dummy();  // generate a random command
            } else {
                crashme = 0;
                string_insert(text, "\n\n#####  Ran out of text to work on.  #####\n\n", NO_UNDO); // insert the string
                dot = text;
                refresh(FALSE);
            }
        }
#endif
        c = get_one_char(); // get a cmd from user
#if ENABLE_FEATURE_VI_CRASHME
        last_input_char = c;
#endif
#if ENABLE_FEATURE_VI_YANKMARK
        // save a copy of the current line- for the 'U" command
        if (begin_line(dot) != cur_line) {
            cur_line = begin_line(dot);
            text_yank(begin_line(dot), end_line(dot), Ureg, PARTIAL);
        }
#endif
#if ENABLE_FEATURE_VI_DOT_CMD
        // If c is a command that changes text[],
        // (re)start remembering the input for the "." command.
        if (!adding2q
         && ioq_start == NULL
         && cmd_mode == 0 // command mode
         && c > '\0' // exclude NUL and non-ASCII chars
         && c < 0x7f // (Unicode and such)
         && strchr(modifying_cmds, c)
        ) {
            start_new_cmd_q(c);
        }
#endif
        do_cmd(c);      // execute the user command

        // poll to see if there is input already waiting. if we are
        // not able to display output fast enough to keep up, skip
        // the display update until we catch up with input.
        if (!readbuffer[0] && mysleep(0) == 0) {
            // no input pending - so update output
            refresh(FALSE);
            show_status_line();
        }
#if ENABLE_FEATURE_VI_CRASHME
        if (crashme > 0)
            crash_test();   // test editor variables
#endif
    }
    //-------------------------------------------------------------------

    go_bottom_and_clear_to_eol();
    cookmode();
#undef cur_line
}

//----- The Colon commands -------------------------------------
#if ENABLE_FEATURE_VI_COLON
static char *get_one_address(char *p, int *addr)    // get colon addr, if present
{
    int st;
    char *q;
    IF_FEATURE_VI_YANKMARK(char c;)

    *addr = -1;         // assume no addr
    if (*p == '.') {    // the current line
        p++;
        q = begin_line(dot);
        *addr = count_lines(text, q);
    }
#if ENABLE_FEATURE_VI_YANKMARK
    else if (*p == '\'') {  // is this a mark addr
        p++;
        c = tolower(*p);
        p++;
        if (c >= 'a' && c <= 'z') {
            // we have a mark
            c = c - 'a';
            q = mark[(unsigned char) c];
            if (q != NULL) {    // is mark valid
                *addr = count_lines(text, q);
            }
        }
    }
#endif
#if ENABLE_FEATURE_VI_SEARCH
    else if (*p == '/') {   // a search pattern
        q = strchrnul(p + 1, '/');
        if (p + 1 != q) {
            // save copy of new pattern
            vi_free(last_search_pattern);
            last_search_pattern = vi_strndup(p, q - p);
        }
        p = q;
        if (*p == '/')
            p++;
        q = char_search(next_line(dot), last_search_pattern + 1,
                        (FORWARD << 1) | FULL);
        if (q != NULL) {
            *addr = count_lines(text, q);
        }
    }
#endif
    else if (*p == '$') {   // the last line in file
        p++;
        q = begin_line(end - 1);
        *addr = count_lines(text, q);
    } else if (isdigit(*p)) {   // specific line number
        sscanf(p, "%d%n", addr, &st);
        p += st;
    } else {
        // unrecognized address - assume -1
        *addr = -1;
    }
    return p;
}

static char *get_address(char *p, int *b, int *e)   // get two colon addrs, if present
{
    //----- get the address' i.e., 1,3   'a,'b  -----
    // get FIRST addr, if present
    while (isblank(*p))
        p++;                // skip over leading spaces
    if (*p == '%') {            // alias for 1,$
        p++;
        *b = 1;
        *e = count_lines(text, end-1);
        goto ga0;
    }
    p = get_one_address(p, b);
    while (isblank(*p))
        p++;
    if (*p == ',') {            // is there a address separator
        p++;
        while (isblank(*p))
            p++;
        // get SECOND addr, if present
        p = get_one_address(p, e);
    }
 ga0:
    while (isblank(*p))
        p++;                // skip over trailing spaces
    return p;
}

# if ENABLE_FEATURE_VI_SET && ENABLE_FEATURE_VI_SETOPTS
static void setops(char *args, int flg_no)
{
    char *eq;
    int index;

    eq = strchr(args, '=');
    if (eq) *eq = '\0';
    index = index_in_strings(OPTS_STR, args + flg_no);
    if (eq) *eq = '=';
    if (index < 0) {
 bad:
        status_line_bold("bad option: %s", args);
        return;
    }

    index = 1 << (index >> 1); // convert to VI_bit

    if (index & VI_TABSTOP) {
        int t;
        if (!eq || flg_no) // no "=NNN" or it is "notabstop"?
            goto bad;
        t = vi_strtou(eq + 1, NULL, 10);
        if (t <= 0 || t > MAX_TABSTOP)
            goto bad;
        tabstop = t;
        return;
    }
    if (eq) goto bad; // boolean option has "="?
    if (flg_no) {
        vi_setops &= ~index;
    } else {
        vi_setops |= index;
    }
}
# endif

#endif /* FEATURE_VI_COLON */

// buf must be no longer than MAX_INPUT_LEN!
static void colon(char *buf)
{
#if !ENABLE_FEATURE_VI_COLON
    /* Simple ":cmd" handler with minimal set of commands */
    char *p = buf;
    int cnt;

    if (*p == ':')
        p++;
    cnt = strlen(p);
    if (cnt == 0)
        return;
    if (strncmp(p, "quit", cnt) == 0
     || strncmp(p, "q!", cnt) == 0
    ) {
        if (modified_count && p[1] != '!') {
            status_line_bold("No write since last change (:%s! overrides)", p);
        } else {
            editing = 0;
        }
        return;
    }
    if (strncmp(p, "write", cnt) == 0
     || strncmp(p, "wq", cnt) == 0
     || strncmp(p, "wn", cnt) == 0
     || (p[0] == 'x' && !p[1])
    ) {
        cnt = file_write(current_filename, text, end - 1);
        if (cnt < 0) {
            if (cnt == -1)
                status_line_bold("Write error: %s", strerror(errno));
        } else {
            modified_count = 0;
            last_modified_count = -1;
            status_line("'%s' %uL, %uC",
                current_filename,
                count_lines(text, end - 1), cnt
            );
            if (p[0] == 'x' || p[1] == 'q' || p[1] == 'n'
             || p[0] == 'X' || p[1] == 'Q' || p[1] == 'N'
            ) {
                editing = 0;
            }
        }
        return;
    }
    if (strncmp(p, "file", cnt) == 0) {
        last_status_cksum = 0;  // force status update
        return;
    }
    if (sscanf(p, "%d", &cnt) > 0) {
        dot = find_line(cnt);
        dot_skip_over_ws();
        return;
    }
    not_implemented(p);
#else

    char c, *buf1, *q, *r;
    char *fn, cmd[MAX_INPUT_LEN], args[MAX_INPUT_LEN];
    int i, l, li, b, e;
    int useforce;
# if ENABLE_FEATURE_VI_SEARCH || ENABLE_FEATURE_ALLOW_EXEC
    char *orig_buf;
# endif

    // :3154    // if (-e line 3154) goto it  else stay put
    // :4,33w! foo  // write a portion of buffer to file "foo"
    // :w       // write all of buffer to current file
    // :q       // quit
    // :q!      // quit- dont care about modified file
    // :'a,'z!sort -u   // filter block through sort
    // :'f      // goto mark "f"
    // :'fl     // list literal the mark "f" line
    // :.r bar  // read file "bar" into buffer before dot
    // :/123/,/abc/d    // delete lines from "123" line to "abc" line
    // :/xyz/   // goto the "xyz" line
    // :s/find/replace/ // substitute pattern "find" with "replace"
    // :!<cmd>  // run <cmd> then return
    //

    if (!buf[0])
        goto ret;
    if (*buf == ':')
        buf++;          // move past the ':'

    li = i = 0;
    b = e = -1;
    q = text;           // assume 1,$ for the range
    r = end - 1;
    li = count_lines(text, end - 1);
    fn = current_filename;

    // look for optional address(es)  :.  :1  :1,9   :'q,'a   :%
    buf = get_address(buf, &b, &e);

# if ENABLE_FEATURE_VI_SEARCH || ENABLE_FEATURE_ALLOW_EXEC
    // remember orig command line
    orig_buf = buf;
# endif

    // get the COMMAND into cmd[]
    buf1 = cmd;
    while (*buf != '\0') {
        if (isspace(*buf))
            break;
        *buf1++ = *buf++;
    }
    *buf1 = '\0';
    // get any ARGuments
    while (isblank(*buf))
        buf++;
    strcpy(args, buf);
    useforce = FALSE;
    buf1 = last_char_is(cmd, '!');
    if (buf1) {
        useforce = TRUE;
        *buf1 = '\0';   // get rid of !
    }
    if (b >= 0) {
        // if there is only one addr, then the addr
        // is the line number of the single line the
        // user wants. So, reset the end
        // pointer to point at end of the "b" line
        q = find_line(b);   // what line is #b
        r = end_line(q);
        li = 1;
    }
    if (e >= 0) {
        // we were given two addrs.  change the
        // end pointer to the addr given by user.
        r = find_line(e);   // what line is #e
        r = end_line(r);
        li = e - b + 1;
    }
    // ------------ now look for the command ------------
    i = strlen(cmd);
    if (i == 0) {       // :123CR goto line #123
        if (b >= 0) {
            dot = find_line(b); // what line is #b
            dot_skip_over_ws();
        }
    }
#if ENABLE_FEATURE_ALLOW_EXEC
    else if (cmd[0] == '!') {   // run a cmd
        int retcode;
        // :!ls   run the <cmd>
        go_bottom_and_clear_to_eol();
        cookmode();
        retcode = system(orig_buf + 1); // run the cmd
        if (retcode)
            printf("\nshell returned %i\n\n", retcode);
        rawmode();
        Hit_Return();           // let user see results
    }
#endif
    else if (cmd[0] == '=' && !cmd[1]) {    // where is the address
        if (b < 0) {    // no addr given- use defaults
            b = e = count_lines(text, dot);
        }
        status_line("%d", b);
    } else if (strncmp(cmd, "delete", i) == 0) {    // delete lines
        if (b < 0) {    // no addr given- use defaults
            q = begin_line(dot);    // assume .,. for the range
            r = end_line(dot);
        }
        dot = yank_delete(q, r, WHOLE, YANKDEL, ALLOW_UNDO);    // save, then delete lines
        dot_skip_over_ws();
    } else if (strncmp(cmd, "edit", i) == 0) {  // Edit a file
        int size;

        // don't edit, if the current file has been modified
        if (modified_count && !useforce) {
            status_line_bold("No write since last change (:%s! overrides)", cmd);
            goto ret;
        }
        if (args[0]) {
            // the user supplied a file name
            fn = args;
        } else if (current_filename && current_filename[0]) {
            // no user supplied name- use the current filename
            // fn = current_filename;  was set by default
        } else {
            // no user file name, no current name- punt
            status_line_bold("No current filename");
            goto ret;
        }

        size = init_text_buffer(fn);

#if ENABLE_FEATURE_VI_YANKMARK
        if (Ureg >= 0 && Ureg < 28) {
            vi_free(reg[Ureg]);    //   free orig line reg- for 'U'
            reg[Ureg] = NULL;
        }
        /*if (YDreg < 28) - always true*/ {
            vi_free(reg[YDreg]);   //   free default yank/delete register
            reg[YDreg] = NULL;
        }
#endif
        // how many lines in text[]?
        li = count_lines(text, end - 1);
        status_line("'%s'%s"
            IF_FEATURE_VI_READONLY("%s")
            " %uL, %uC",
            current_filename,
            (size < 0 ? " [New file]" : ""),
            IF_FEATURE_VI_READONLY(
                ((readonly_mode) ? " [Readonly]" : ""),
            )
            li, (int)(end - text)
        );
    } else if (strncmp(cmd, "file", i) == 0) {  // what File is this
        if (b != -1 || e != -1) {
            status_line_bold("No address allowed on this command");
            goto ret;
        }
        if (args[0]) {
            // user wants a new filename
            vi_free(current_filename);
            current_filename = vi_strdup(args);
        } else {
            // user wants file status info
            last_status_cksum = 0;  // force status update
        }
    } else if (strncmp(cmd, "features", i) == 0) {  // what features are available
        // print out values of all features
        go_bottom_and_clear_to_eol();
        cookmode();
        show_help();
        rawmode();
        Hit_Return();
    } else if (strncmp(cmd, "list", i) == 0) {  // literal print line
        if (b < 0) {    // no addr given- use defaults
            q = begin_line(dot);    // assume .,. for the range
            r = end_line(dot);
        }
        go_bottom_and_clear_to_eol();
        puts("\r");
        for (; q <= r; q++) {
            int c_is_no_print;

            c = *q;
            c_is_no_print = (c & 0x80) && !Isprint(c);
            if (c_is_no_print) {
                c = '.';
                standout_start();
            }
            if (c == '\n') {
                write1("$\r");
            } else if (c < ' ' || c == 127) {
                vi_putchar('^');
                if (c == 127)
                    c = '?';
                else
                    c += '@';
            }
            vi_putchar(c);
            if (c_is_no_print)
                standout_end();
        }
        Hit_Return();
    } else if (strncmp(cmd, "quit", i) == 0 // quit
            || strncmp(cmd, "next", i) == 0 // edit next file
            || strncmp(cmd, "prev", i) == 0 // edit previous file
    ) {
        int n;
        if (useforce) {
            if (*cmd == 'q') {
                // force end of argv list
                options.optind = cmdline_filecnt;
            }
            editing = 0;
            goto ret;
        }
        // don't exit if the file been modified
        if (modified_count) {
            status_line_bold("No write since last change (:%s! overrides)", cmd);
            goto ret;
        }
        // are there other file to edit
        n = cmdline_filecnt - options.optind - 1;
        if (*cmd == 'q' && n > 0) {
            status_line_bold("%u more file(s) to edit", n);
            goto ret;
        }
        if (*cmd == 'n' && n <= 0) {
            status_line_bold("No more files to edit");
            goto ret;
        }
        if (*cmd == 'p') {
            // are there previous files to edit
            if (options.optind < 1) {
                status_line_bold("No previous files to edit");
                goto ret;
            }
            options.optind -= 2;
        }
        editing = 0;
    } else if (strncmp(cmd, "read", i) == 0) {  // read file into text[]
        int size;

        fn = args;
        if (!fn[0]) {
            status_line_bold("No filename given");
            goto ret;
        }
        if (b < 0) {    // no addr given- use defaults
            q = begin_line(dot);    // assume "dot"
        }
        // read after current line- unless user said ":0r foo"
        if (b != 0)
            q = next_line(q);
        { // dance around potentially-reallocated text[]
            uintptr_t ofs = q - text;
            size = file_insert(fn, q, 0);
            q = text + ofs;
        }
        if (size < 0)
            goto ret;   // nothing was inserted
        // how many lines in text[]?
        li = count_lines(q, q + size - 1);
        status_line("'%s'"
            IF_FEATURE_VI_READONLY("%s")
            " %uL, %uC",
            fn,
            IF_FEATURE_VI_READONLY((readonly_mode ? " [Readonly]" : ""),)
            li, size
        );
        if (size > 0) {
            // if the insert is before "dot" then we need to update
            if (q <= dot)
                dot += size;
        }
    } else if (strncmp(cmd, "rewind", i) == 0) {    // rewind cmd line args
        if (modified_count && !useforce) {
            status_line_bold("No write since last change (:%s! overrides)", cmd);
        } else {
            // reset the filenames to edit
            options.optind = -1; /* start from 0th file */
            editing = 0;
        }
#if ENABLE_FEATURE_VI_SET
    } else if (strncmp(cmd, "set", i) == 0) {   // set or clear features
#if ENABLE_FEATURE_VI_SETOPTS
        char *argp, *argn, oldch;
#endif
        // only blank is regarded as args delimiter. What about tab '\t'?
        if (!args[0] || strcmp(args, "all") == 0) {
            // print out values of all options
#if ENABLE_FEATURE_VI_SETOPTS
            status_line_bold(
                "%sautoindent "
                "%sflash "
                "%signorecase "
                "%sshowmatch "
                "tabstop=%u",
                autoindent ? "" : "no",
                err_method ? "" : "no",
                ignorecase ? "" : "no",
                showmatch ? "" : "no",
                tabstop
            );
#endif
            goto ret;
        }
#if ENABLE_FEATURE_VI_SETOPTS
        argp = args;
        while (*argp) {
            i = 0;
            if (argp[0] == 'n' && argp[1] == 'o') // "noXXX"
                i = 2;
            argn = skip_non_whitespace(argp);
            oldch = *argn;
            *argn = '\0';
            setops(argp, i);
            *argn = oldch;
            argp = skip_whitespace(argn);
        }
#endif /* FEATURE_VI_SETOPTS */
#endif /* FEATURE_VI_SET */
#if ENABLE_FEATURE_VI_SEARCH
    } else if (cmd[0] == 's') { // substitute a pattern with a replacement pattern
        char *F, *R, *flags;
        size_t len_F, len_R;
        int gflag;      // global replace flag
#if ENABLE_FEATURE_VI_UNDO
        int dont_chain_first_item = ALLOW_UNDO;
#endif

        // F points to the "find" pattern
        // R points to the "replace" pattern
        // replace the cmd line delimiters "/" with NULs
        c = orig_buf[1];    // what is the delimiter
        F = orig_buf + 2;   // start of "find"
        R = strchr(F, c);   // middle delimiter
        if (!R)
            goto colon_s_fail;
        len_F = R - F;
        *R++ = '\0';    // terminate "find"
        flags = strchr(R, c);
        if (!flags)
            goto colon_s_fail;
        len_R = flags - R;
        *flags++ = '\0';    // terminate "replace"
        gflag = *flags;

        q = begin_line(q);
        if (b < 0) {    // maybe :s/foo/bar/
            q = begin_line(dot);      // start with cur line
            b = count_lines(text, q); // cur line number
        }
        if (e < 0)
            e = b;      // maybe :.s/foo/bar/

        for (i = b; i <= e; i++) {  // so, :20,23 s \0 find \0 replace \0
            char *ls = q;       // orig line start
            char *found;
 vc4:
            found = char_search(q, F, (FORWARD << 1) | LIMITED);    // search cur line only for "find"
            if (found) {
                uintptr_t bias;
                // we found the "find" pattern - delete it
                // For undo support, the first item should not be chained
                text_hole_delete(found, found + len_F - 1, dont_chain_first_item);
#if ENABLE_FEATURE_VI_UNDO
                dont_chain_first_item = ALLOW_UNDO_CHAIN;
#endif
                // insert the "replace" patern
                bias = string_insert(found, R, ALLOW_UNDO_CHAIN);
                found += bias;
                ls += bias;
                /*q += bias; - recalculated anyway */
                // check for "global"  :s/foo/bar/g
                if (gflag == 'g') {
                    if ((found + len_R) < end_line(ls)) {
                        q = found + len_R;
                        goto vc4;   // don't let q move past cur line
                    }
                }
            }
            q = next_line(ls);
        }
#endif /* FEATURE_VI_SEARCH */
    } else if (strncmp(cmd, "version", i) == 0) {  // show software version
        status_line(BB_VER " " BB_BT);
    } else if (strncmp(cmd, "write", i) == 0  // write text to file
            || strncmp(cmd, "wq", i) == 0
            || strncmp(cmd, "wn", i) == 0
            || (cmd[0] == 'x' && !cmd[1])
    ) {
        int size;
        //int forced = FALSE;

        // is there a file name to write to?
        if (args[0]) {
            struct stat statbuf;

            if (!useforce && (fn == NULL || strcmp(fn, args) != 0) &&
                    stat(args, &statbuf) == 0) {
                status_line_bold("File exists (:w! overrides)");
                goto ret;
            }
            fn = args;
        }
#if ENABLE_FEATURE_VI_READONLY
        if (readonly_mode && !useforce) {
            status_line_bold("'%s' is read only", fn);
            goto ret;
        }
#endif
        // how many lines in text[]?
        li = count_lines(q, r);
        size = r - q + 1;
        //if (useforce) {
            // if "fn" is not write-able, chmod u+w
            // sprintf(syscmd, "chmod u+w %s", fn);
            // system(syscmd);
            // forced = TRUE;
        //}
        l = file_write(fn, q, r);
        //if (useforce && forced) {
            // chmod u-w
            // sprintf(syscmd, "chmod u-w %s", fn);
            // system(syscmd);
            // forced = FALSE;
        //}
        if (l < 0) {
            if (l == -1)
                status_line_bold_errno(fn);
        } else {
            // how many lines written
            li = count_lines(q, q + l - 1);
            status_line("'%s' %uL, %uC", fn, li, l);
            if (l == size) {
                if (q == text && q + l == end) {
                    modified_count = 0;
                    last_modified_count = -1;
                }
                if (cmd[0] == 'x'
                 || cmd[1] == 'q' || cmd[1] == 'n'
                 || cmd[1] == 'Q' || cmd[1] == 'N'
                ) {
                    editing = 0;
                }
            }
        }
#if ENABLE_FEATURE_VI_YANKMARK
    } else if (strncmp(cmd, "yank", i) == 0) {  // yank lines
        if (b < 0) {    // no addr given- use defaults
            q = begin_line(dot);    // assume .,. for the range
            r = end_line(dot);
        }
        text_yank(q, r, YDreg, WHOLE);
        li = count_lines(q, r);
        status_line("Yank %d lines (%d chars) into [%c]",
                li, strlen(reg[YDreg]), what_reg());
#endif
    } else {
        // cmd unknown
        not_implemented(cmd);
    }
 ret:
    dot = bound_dot(dot);   // make sure "dot" is valid
    return;
#if ENABLE_FEATURE_VI_SEARCH
 colon_s_fail:
    status_line(":s expression missing delimiters");
#endif
#endif /* FEATURE_VI_COLON */
}

static void Hit_Return(void)
{
    int c;

    standout_start();
    write1("[Hit return to continue]");
    standout_end();
    while ((c = get_one_char()) != '\n' && c != '\r')
        continue;
    redraw(TRUE);       // force redraw all
}

static int next_tabstop(int col)
{
    return col + ((tabstop - 1) - (col % tabstop));
}

//----- Synchronize the cursor to Dot --------------------------
static void sync_cursor(char *d, int *row, int *col)
{
    char *beg_cur;  // begin and end of "d" line
    char *tp;
    int cnt, ro, co;

    beg_cur = begin_line(d);    // first char of cur line

    if (beg_cur < screenbegin) {
        // "d" is before top line on screen
        // how many lines do we have to move
        cnt = count_lines(beg_cur, screenbegin);
 sc1:
        screenbegin = beg_cur;
        if (cnt > (rows - 1) / 2) {
            // we moved too many lines. put "dot" in middle of screen
            for (cnt = 0; cnt < (rows - 1) / 2; cnt++) {
                screenbegin = prev_line(screenbegin);
            }
        }
    } else {
        char *end_scr;  // begin and end of screen
        end_scr = end_screen(); // last char of screen
        if (beg_cur > end_scr) {
            // "d" is after bottom line on screen
            // how many lines do we have to move
            cnt = count_lines(end_scr, beg_cur);
            if (cnt > (rows - 1) / 2)
                goto sc1;   // too many lines
            for (ro = 0; ro < cnt - 1; ro++) {
                // move screen begin the same amount
                screenbegin = next_line(screenbegin);
                // now, move the end of screen
                end_scr = next_line(end_scr);
                end_scr = end_line(end_scr);
            }
        }
    }
    // "d" is on screen- find out which row
    tp = screenbegin;
    for (ro = 0; ro < rows - 1; ro++) { // drive "ro" to correct row
        if (tp == beg_cur)
            break;
        tp = next_line(tp);
    }

    // find out what col "d" is on
    co = 0;
    while (tp < d) { // drive "co" to correct column
        if (*tp == '\n') //vda || *tp == '\0')
            break;
        if (*tp == '\t') {
            // handle tabs like real vi
            if (d == tp && cmd_mode) {
                break;
            }
            co = next_tabstop(co);
        } else if ((unsigned char)*tp < ' ' || *tp == 0x7f) {
            co++; // display as ^X, use 2 columns
        }
        co++;
        tp++;
    }

    // "co" is the column where "dot" is.
    // The screen has "columns" columns.
    // The currently displayed columns are  0+offset -- columns+ofset
    // |-------------------------------------------------------------|
    //               ^ ^                                ^
    //        offset | |------- columns ----------------|
    //
    // If "co" is already in this range then we do not have to adjust offset
    //      but, we do have to subtract the "offset" bias from "co".
    // If "co" is outside this range then we have to change "offset".
    // If the first char of a line is a tab the cursor will try to stay
    //  in column 7, but we have to set offset to 0.

    if (co < 0 + offset) {
        offset = co;
    }
    if (co >= columns + offset) {
        offset = co - columns + 1;
    }
    // if the first char of the line is a tab, and "dot" is sitting on it
    //  force offset to 0.
    if (d == beg_cur && *d == '\t') {
        offset = 0;
    }
    co -= offset;

    *row = ro;
    *col = co;
}

//----- Text Movement Routines ---------------------------------
static char *begin_line(char *p) // return pointer to first char cur line
{
    if (p > text) {
        p = memrchr(text, '\n', p - text);
        if (!p)
            return text;
        return p + 1;
    }
    return p;
}

static char *end_line(char *p) // return pointer to NL of cur line
{
    if (p < end - 1) {
        p = memchr(p, '\n', end - p - 1);
        if (!p)
            return end - 1;
    }
    return p;
}

static char *dollar_line(char *p) // return pointer to just before NL line
{
    p = end_line(p);
    // Try to stay off of the Newline
    if (*p == '\n' && (p - begin_line(p)) > 0)
        p--;
    return p;
}

static char *prev_line(char *p) // return pointer first char prev line
{
    p = begin_line(p);  // goto begining of cur line
    if (p > text && p[-1] == '\n')
        p--;            // step to prev line
    p = begin_line(p);  // goto begining of prev line
    return p;
}

static char *next_line(char *p) // return pointer first char next line
{
    p = end_line(p);
    if (p < end - 1 && *p == '\n')
        p++;            // step to next line
    return p;
}

//----- Text Information Routines ------------------------------
static char *end_screen(void)
{
    char *q;
    int cnt;

    // find new bottom line
    q = screenbegin;
    for (cnt = 0; cnt < rows - 2; cnt++)
        q = next_line(q);
    q = end_line(q);
    return q;
}

// count line from start to stop
static int count_lines(char *start, char *stop)
{
    char *q;
    int cnt;

    if (stop < start) { // start and stop are backwards- reverse them
        q = start;
        start = stop;
        stop = q;
    }
    cnt = 0;
    stop = end_line(stop);
    while (start <= stop && start <= end - 1) {
        start = end_line(start);
        if (*start == '\n')
            cnt++;
        start++;
    }
    return cnt;
}

static char *find_line(int li)  // find begining of line #li
{
    char *q;

    for (q = text; li > 1; li--) {
        q = next_line(q);
    }
    return q;
}

//----- Dot Movement Routines ----------------------------------
static void dot_left(void)
{
    undo_queue_commit();
    if (dot > text && dot[-1] != '\n')
        dot--;
}

static void dot_right(void)
{
    undo_queue_commit();
    if (dot < end - 1 && *dot != '\n')
        dot++;
}

static void dot_begin(void)
{
    undo_queue_commit();
    dot = begin_line(dot);  // return pointer to first char cur line
}

static void dot_end(void)
{
    undo_queue_commit();
    dot = end_line(dot);    // return pointer to last char cur line
}

static char *move_to_col(char *p, int l)
{
    int co;

    p = begin_line(p);
    co = 0;
    while (co < l && p < end) {
        if (*p == '\n') //vda || *p == '\0')
            break;
        if (*p == '\t') {
            co = next_tabstop(co);
        } else if (*p < ' ' || *p == 127) {
            co++; // display as ^X, use 2 columns
        }
        co++;
        p++;
    }
    return p;
}

static void dot_next(void)
{
    undo_queue_commit();
    dot = next_line(dot);
}

static void dot_prev(void)
{
    undo_queue_commit();
    dot = prev_line(dot);
}

static void dot_to_char(int cmd)
{
    char *q = dot;
    int dir = islower(cmd) ? FORWARD : BACK;

    if (last_search_char == 0)
        return;

    do {
        do {
            q += dir;
            if ((dir == FORWARD ? q > end - 1 : q < text) || *q == '\n')
                return;
        } while (*q != last_search_char);
    } while (--cmdcnt > 0);

    dot = q;

    // place cursor before/after char as required
    if (cmd == 't')
        dot_left();
    else if (cmd == 'T')
        dot_right();
}

static void dot_scroll(int cnt, int dir)
{
    char *q;

    undo_queue_commit();
    for (; cnt > 0; cnt--) {
        if (dir < 0) {
            // scroll Backwards
            // ctrl-Y scroll up one line
            screenbegin = prev_line(screenbegin);
        } else {
            // scroll Forwards
            // ctrl-E scroll down one line
            screenbegin = next_line(screenbegin);
        }
    }
    // make sure "dot" stays on the screen so we dont scroll off
    if (dot < screenbegin)
        dot = screenbegin;
    q = end_screen();   // find new bottom line
    if (dot > q)
        dot = begin_line(q);    // is dot is below bottom line?
    dot_skip_over_ws();
}

static void dot_skip_over_ws(void)
{
    // skip WS
    while (isspace((unsigned char)*dot) && *dot != '\n' && dot < end - 1)
        dot++;
}

static char *bound_dot(char *p) // make sure  text[0] <= P < "end"
{
    if (p >= end && end > text) {
        p = end - 1;
        indicate_error();
    }
    if (p < text) {
        p = text;
        indicate_error();
    }
    return p;
}

//----- Helper Utility Routines --------------------------------

//----------------------------------------------------------------
//----- Char Routines --------------------------------------------
/* Chars that are part of a word-
 *    0123456789_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
 * Chars that are Not part of a word (stoppers)
 *    !"#$%&'()*+,-./:;<=>?@[\]^`{|}~
 * Chars that are WhiteSpace
 *    TAB NEWLINE VT FF RETURN SPACE
 * DO NOT COUNT NEWLINE AS WHITESPACE
 */

static void new_screen(int ro, int co)
{
    char *s;

    vi_free(screen);
    screensize = ro * co + 8;
    s = screen = vi_malloc(screensize);
    // initialize the new screen. assume this will be a empty file.
    screen_erase();
    // non-existent text[] lines start with a tilde (~).
    //screen[(1 * co) + 0] = '~';
    //screen[(2 * co) + 0] = '~';
    //..
    //screen[((ro-2) * co) + 0] = '~';
    ro -= 2;
    while (--ro >= 0) {
        s += co;
        *s = '~';
    }
}

#if ENABLE_FEATURE_VI_SEARCH

# if ENABLE_FEATURE_VI_REGEX_SEARCH

// search for pattern starting at p
static char *char_search(char *p, const char *pat, int dir_and_range)
{
    struct re_pattern_buffer preg;
    const char *err;
    char *q;
    int i;
    int size;
    int range;

    re_syntax_options = RE_SYNTAX_POSIX_EXTENDED;
    if (ignorecase)
        re_syntax_options = RE_SYNTAX_POSIX_EXTENDED | RE_ICASE;

    rt_memset(&preg, 0, sizeof(preg));
    err = re_compile_pattern(pat, strlen(pat), &preg);
    if (err != NULL) {
        status_line_bold("bad search pattern '%s': %s", pat, err);
        return p;
    }

    range = (dir_and_range & 1);
    q = end - 1; // if FULL
    if (range == LIMITED)
        q = next_line(p);
    if (dir_and_range < 0) { // BACK?
        q = text;
        if (range == LIMITED)
            q = prev_line(p);
    }

    // RANGE could be negative if we are searching backwards
    range = q - p;
    q = p;
    size = range;
    if (range < 0) {
        size = -size;
        q = p - size;
        if (q < text)
            q = text;
    }
    // search for the compiled pattern, preg, in p[]
    // range < 0: search backward
    // range > 0: search forward
    // 0 < start < size
    // re_search() < 0: not found or error
    // re_search() >= 0: index of found pattern
    //           struct pattern   char     int   int    int    struct reg
    // re_search(*pattern_buffer, *string, size, start, range, *regs)
    i = re_search(&preg, q, size, /*start:*/ 0, range, /*struct re_registers*:*/ NULL);
    regfree(&preg);
    if (i < 0)
        return NULL;
    if (dir_and_range > 0) // FORWARD?
        p = p + i;
    else
        p = p - i;
    return p;
}

# else

#  if ENABLE_FEATURE_VI_SETOPTS
static int mycmp(const char *s1, const char *s2, int len)
{
    if (ignorecase) {
        return strncasecmp(s1, s2, len);
    }
    return strncmp(s1, s2, len);
}
#  else
#   define mycmp strncmp
#  endif

static char *char_search(char *p, const char *pat, int dir_and_range)
{
    char *start, *stop;
    int len;
    int range;

    len = strlen(pat);
    range = (dir_and_range & 1);
    if (dir_and_range > 0) { //FORWARD?
        stop = end - 1; // assume range is p..end-1
        if (range == LIMITED)
            stop = next_line(p);    // range is to next line
        for (start = p; start < stop; start++) {
            if (mycmp(start, pat, len) == 0) {
                return start;
            }
        }
    } else { //BACK
        stop = text;    // assume range is text..p
        if (range == LIMITED)
            stop = prev_line(p);    // range is to prev line
        for (start = p - len; start >= stop; start--) {
            if (mycmp(start, pat, len) == 0) {
                return start;
            }
        }
    }
    // pattern not found
    return NULL;
}

# endif

#endif /* FEATURE_VI_SEARCH */

static char *char_insert(char *p, char c, int undo) // insert the char c at 'p'
{
    if (c == 22) {      // Is this an ctrl-V?
        p += stupid_insert(p, '^'); // use ^ to indicate literal next
        refresh(FALSE); // show the ^
        c = get_one_char();
        *p = c;
#if ENABLE_FEATURE_VI_UNDO
        undo_push_insert(p, 1, undo);
#else
        modified_count++;
#endif /* ENABLE_FEATURE_VI_UNDO */
        p++;
    } else if (c == 27) {   // Is this an ESC?
        cmd_mode = 0;
        undo_queue_commit();
        cmdcnt = 0;
        end_cmd_q();    // stop adding to q
        last_status_cksum = 0;  // force status update
        if ((p[-1] != '\n') && (dot > text)) {
            p--;
        }
    } else if (
        #ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
            c == term_orig.c_cc[VERASE] ||
        #endif
            c == 8 || c == 127) { // Is this a BS
        if (p > text) {
            p--;
            p = text_hole_delete(p, p, ALLOW_UNDO_QUEUED);  // shrink buffer 1 char
        }
    } else {
        // insert a char into text[]
        if (c == 13)
            c = '\n';   // translate \r to \n
#if ENABLE_FEATURE_VI_UNDO
# if ENABLE_FEATURE_VI_UNDO_QUEUE
        if (c == '\n')
            undo_queue_commit();
# endif
        undo_push_insert(p, 1, undo);
#else
        modified_count++;
#endif /* ENABLE_FEATURE_VI_UNDO */
        p += 1 + stupid_insert(p, c);   // insert the char
#if ENABLE_FEATURE_VI_SETOPTS
        if (showmatch && strchr(")]}", c) != NULL) {
            showmatching(p - 1);
        }
        if (autoindent && c == '\n') {  // auto indent the new line
            char *q;
            size_t len;
            q = prev_line(p);   // use prev line as template
            len = strspn(q, " \t"); // space or tab
            if (len) {
                uintptr_t bias;
                bias = text_hole_make(p, len);
                p += bias;
                q += bias;
#if ENABLE_FEATURE_VI_UNDO
                undo_push_insert(p, len, undo);
#endif
                rt_memcpy(p, q, len);
                p += len;
            }
        }
#endif
    }
    return p;
}

// might reallocate text[]! use p += stupid_insert(p, ...),
// and be careful to not use pointers into potentially freed text[]!
static uintptr_t stupid_insert(char *p, char c) // stupidly insert the char c at 'p'
{
    uintptr_t bias;
    bias = text_hole_make(p, 1);
    p += bias;
    *p = c;
    return bias;
}

static int at_eof(const char *s)
{
    // does 's' point to end of file, even with no terminating newline?
    return ((s == end - 2 && s[1] == '\n') || s == end - 1);
}

static int find_range(char **start, char **stop, char c)
{
    char *save_dot, *p, *q, *t;
    int buftype = -1;

    save_dot = dot;
    p = q = dot;

    if (strchr("cdy><", c)) {
        // these cmds operate on whole lines
        buftype = WHOLE;
        if (--cmdcnt > 0)
            do_cmd('j');
    } else if (strchr("^%$0bBeEfFtTh|{}\b\177", c)) {
        // These cmds operate on char positions
        buftype = PARTIAL;
        do_cmd(c);      // execute movement cmd
        if (p == dot)   // no movement is an error
            buftype = -1;
    } else if (strchr("wW", c)) {
        buftype = MULTI;
        do_cmd(c);      // execute movement cmd
        // step back one char, but not if we're at end of file
        if (dot > p && !at_eof(dot))
            dot--;
    } else if (strchr("GHL+-jk\r\n", c)) {
        // these operate on whole lines
        buftype = WHOLE;
        do_cmd(c);      // execute movement cmd
    } else if (c == ' ' || c == 'l') {
        // forward motion by character
        int tmpcnt = (cmdcnt ? cmdcnt : 1);
        buftype = PARTIAL;
        do_cmd(c);      // execute movement cmd
        // exclude last char unless range isn't what we expected
        // this indicates we've hit EOL
        if (tmpcnt == dot - p)
            dot--;
    }

    if (buftype == -1)
        return buftype;

    q = dot;
    if (q < p) {
        t = q;
        q = p;
        p = t;
    }

    // movements which don't include end of range
    if (q > p) {
        if (strchr("^0bBFTh|\b\177", c)) {
            q--;
        } else if (strchr("{}", c)) {
            buftype = (p == begin_line(p) && (*q == '\n' || at_eof(q))) ?
                            WHOLE : MULTI;
            if (!at_eof(q)) {
                q--;
                if (q > p && p != begin_line(p))
                    q--;
            }
        }
    }

    if (buftype == WHOLE) {
        p = begin_line(p);
        q = end_line(q);
    }

    *start = p;
    *stop = q;
    dot = save_dot;
    return buftype;
}

static int st_test(char *p, int type, int dir, char *tested)
{
    char c, c0, ci;
    int test, inc;

    inc = dir;
    c = c0 = p[0];
    ci = p[inc];
    test = 0;

    if (type == S_BEFORE_WS) {
        c = ci;
        test = (!isspace((unsigned char)c) || c == '\n');
    }
    if (type == S_TO_WS) {
        c = c0;
        test = (!isspace((unsigned char)c) || c == '\n');
    }
    if (type == S_OVER_WS) {
        c = c0;
        test = isspace((unsigned char)c);
    }
    if (type == S_END_PUNCT) {
        c = ci;
        test = ispunct((unsigned char)c);
    }
    if (type == S_END_ALNUM) {
        c = ci;
        test = (isalnum((unsigned char)c) || c == '_');
    }
    *tested = c;
    return test;
}

static char *skip_thing(char *p, int linecnt, int dir, int type)
{
    char c;

    while (st_test(p, type, dir, &c)) {
        // make sure we limit search to correct number of lines
        if (c == '\n' && --linecnt < 1)
            break;
        if (dir >= 0 && p >= end - 1)
            break;
        if (dir < 0 && p <= text)
            break;
        p += dir;       // move to next char
    }
    return p;
}

// find matching char of pair  ()  []  {}
// will crash if c is not one of these
static char *find_pair(char *p, const char c)
{
    const char *braces = "()[]{}";
    char match;
    int dir, level;

    dir = strchr(braces, c) - braces;
    dir ^= 1;
    match = braces[dir];
    dir = ((dir & 1) << 1) - 1; /* 1 for ([{, -1 for )\} */

    // look for match, count levels of pairs  (( ))
    level = 1;
    for (;;) {
        p += dir;
        if (p < text || p >= end)
            return NULL;
        if (*p == c)
            level++;    // increase pair levels
        if (*p == match) {
            level--;    // reduce pair level
            if (level == 0)
                return p; // found matching pair
        }
    }
}

#if ENABLE_FEATURE_VI_SETOPTS
// show the matching char of a pair,  ()  []  {}
static void showmatching(char *p)
{
    char *q, *save_dot;

    // we found half of a pair
    q = find_pair(p, *p);   // get loc of matching char
    if (q == NULL) {
        indicate_error();   // no matching char
    } else {
        // "q" now points to matching pair
        save_dot = dot; // remember where we are
        dot = q;        // go to new loc
        refresh(FALSE); // let the user see it
        mysleep(40);    // give user some time
        dot = save_dot; // go back to old loc
        refresh(FALSE);
    }
}
#endif /* FEATURE_VI_SETOPTS */

#if ENABLE_FEATURE_VI_UNDO
static void flush_undo_data(void)
{
    struct undo_object *undo_entry;

    while (undo_stack_tail) {
        undo_entry = undo_stack_tail;
        undo_stack_tail = undo_entry->prev;
        vi_free(undo_entry);
    }
}

// Undo functions and hooks added by Jody Bruchon (jody@jodybruchon.com)
// Add to the undo stack
static void undo_push(char *src, unsigned length, uint8_t u_type)
{
    struct undo_object *undo_entry;

    // "u_type" values
    // UNDO_INS: insertion, undo will remove from buffer
    // UNDO_DEL: deleted text, undo will restore to buffer
    // UNDO_{INS,DEL}_CHAIN: Same as above but also calls undo_pop() when complete
    // The CHAIN operations are for handling multiple operations that the user
    // performs with a single action, i.e. REPLACE mode or find-and-replace commands
    // UNDO_{INS,DEL}_QUEUED: If queuing feature is enabled, allow use of the queue
    // for the INS/DEL operation. The raw values should be equal to the values of
    // UNDO_{INS,DEL} ORed with UNDO_QUEUED_FLAG

#if ENABLE_FEATURE_VI_UNDO_QUEUE
    // This undo queuing functionality groups multiple character typing or backspaces
    // into a single large undo object. This greatly reduces calls to malloc() for
    // single-character operations while typing and has the side benefit of letting
    // an undo operation remove chunks of text rather than a single character.
    switch (u_type) {
    case UNDO_EMPTY:    // Just in case this ever happens...
        return;
    case UNDO_DEL_QUEUED:
        if (length != 1)
            return; // Only queue single characters
        switch (undo_queue_state) {
        case UNDO_EMPTY:
            undo_queue_state = UNDO_DEL;
        case UNDO_DEL:
            undo_queue_spos = src;
            undo_q++;
            undo_queue[CONFIG_FEATURE_VI_UNDO_QUEUE_MAX - undo_q] = *src;
            // If queue is full, dump it into an object
            if (undo_q == CONFIG_FEATURE_VI_UNDO_QUEUE_MAX)
                undo_queue_commit();
            return;
        case UNDO_INS:
            // Switch from storing inserted text to deleted text
            undo_queue_commit();
            undo_push(src, length, UNDO_DEL_QUEUED);
            return;
        }
        break;
    case UNDO_INS_QUEUED:
        if (length < 1)
            return;
        switch (undo_queue_state) {
        case UNDO_EMPTY:
            undo_queue_state = UNDO_INS;
            undo_queue_spos = src;
        case UNDO_INS:
            while (length--) {
                undo_q++;   // Don't need to save any data for insertions
                if (undo_q == CONFIG_FEATURE_VI_UNDO_QUEUE_MAX)
                    undo_queue_commit();
            }
            return;
        case UNDO_DEL:
            // Switch from storing deleted text to inserted text
            undo_queue_commit();
            undo_push(src, length, UNDO_INS_QUEUED);
            return;
        }
        break;
    }
#else
    // If undo queuing is disabled, ignore the queuing flag entirely
    u_type = u_type & ~UNDO_QUEUED_FLAG;
#endif

    // Allocate a new undo object
    if (u_type == UNDO_DEL || u_type == UNDO_DEL_CHAIN) {
        // For UNDO_DEL objects, save deleted text
        if ((text + length) == end)
            length--;
        // If this deletion empties text[], strip the newline. When the buffer becomes
        // zero-length, a newline is added back, which requires this to compensate.
        undo_entry = vi_zalloc(offsetof(struct undo_object, undo_text) + length);
        rt_memcpy(undo_entry->undo_text, src, length);
    } else {
        undo_entry = vi_zalloc(sizeof(*undo_entry));
    }
    undo_entry->length = length;
#if ENABLE_FEATURE_VI_UNDO_QUEUE
    if ((u_type & UNDO_USE_SPOS) != 0) {
        undo_entry->start = undo_queue_spos - text; // use start position from queue
    } else {
        undo_entry->start = src - text; // use offset from start of text buffer
    }
    u_type = (u_type & ~UNDO_USE_SPOS);
#else
    undo_entry->start = src - text;
#endif
    undo_entry->u_type = u_type;

    // Push it on undo stack
    undo_entry->prev = undo_stack_tail;
    undo_stack_tail = undo_entry;
    modified_count++;
}

static void undo_push_insert(char *p, int len, int undo)
{
    switch (undo) {
    case ALLOW_UNDO:
        undo_push(p, len, UNDO_INS);
        break;
    case ALLOW_UNDO_CHAIN:
        undo_push(p, len, UNDO_INS_CHAIN);
        break;
# if ENABLE_FEATURE_VI_UNDO_QUEUE
    case ALLOW_UNDO_QUEUED:
        undo_push(p, len, UNDO_INS_QUEUED);
        break;
# endif
    }
}

// Undo the last operation
static void undo_pop(void)
{
    int repeat;
    char *u_start, *u_end;
    struct undo_object *undo_entry;

    // Commit pending undo queue before popping (should be unnecessary)
    undo_queue_commit();

    undo_entry = undo_stack_tail;
    // Check for an empty undo stack
    if (!undo_entry) {
        status_line("Already at oldest change");
        return;
    }

    switch (undo_entry->u_type) {
    case UNDO_DEL:
    case UNDO_DEL_CHAIN:
        // make hole and put in text that was deleted; deallocate text
        u_start = text + undo_entry->start;
        text_hole_make(u_start, undo_entry->length);
        rt_memcpy(u_start, undo_entry->undo_text, undo_entry->length);
        status_line("Undo [%d] %s %d chars at position %d",
            modified_count, "restored",
            undo_entry->length, undo_entry->start
        );
        break;
    case UNDO_INS:
    case UNDO_INS_CHAIN:
        // delete what was inserted
        u_start = undo_entry->start + text;
        u_end = u_start - 1 + undo_entry->length;
        text_hole_delete(u_start, u_end, NO_UNDO);
        status_line("Undo [%d] %s %d chars at position %d",
            modified_count, "deleted",
            undo_entry->length, undo_entry->start
        );
        break;
    }
    repeat = 0;
    switch (undo_entry->u_type) {
    // If this is the end of a chain, lower modification count and refresh display
    case UNDO_DEL:
    case UNDO_INS:
        dot = (text + undo_entry->start);
        refresh(FALSE);
        break;
    case UNDO_DEL_CHAIN:
    case UNDO_INS_CHAIN:
        repeat = 1;
        break;
    }
    // Deallocate the undo object we just processed
    undo_stack_tail = undo_entry->prev;
    vi_free(undo_entry);
    modified_count--;
    // For chained operations, continue popping all the way down the chain.
    if (repeat) {
        undo_pop(); // Follow the undo chain if one exists
    }
}

#if ENABLE_FEATURE_VI_UNDO_QUEUE
// Flush any queued objects to the undo stack
static void undo_queue_commit(void)
{
    // Pushes the queue object onto the undo stack
    if (undo_q > 0) {
        // Deleted character undo events grow from the end
        undo_push(undo_queue + CONFIG_FEATURE_VI_UNDO_QUEUE_MAX - undo_q,
            undo_q,
            (undo_queue_state | UNDO_USE_SPOS)
        );
        undo_queue_state = UNDO_EMPTY;
        undo_q = 0;
    }
}
#endif

#endif /* ENABLE_FEATURE_VI_UNDO */

// open a hole in text[]
// might reallocate text[]! use p += text_hole_make(p, ...),
// and be careful to not use pointers into potentially freed text[]!
static uintptr_t text_hole_make(char *p, int size)  // at "p", make a 'size' byte hole
{
    uintptr_t bias = 0;

    if (size <= 0)
        return bias;
    end += size;        // adjust the new END
    if (end >= (text + text_size)) {
        char *new_text;
        text_size += end - (text + text_size) + 10240;
        new_text = vi_realloc(text, text_size);
        bias = (new_text - text);
        screenbegin += bias;
        dot         += bias;
        end         += bias;
        p           += bias;
#if ENABLE_FEATURE_VI_YANKMARK
        {
            int i;
            for (i = 0; i < ARRAY_SIZE(mark); i++)
                if (mark[i])
                    mark[i] += bias;
        }
#endif
        text = new_text;
    }
    memmove(p + size, p, end - size - p);
    rt_memset(p, ' ', size);   // clear new hole
    return bias;
}

//  close a hole in text[]
//  "undo" value indicates if this operation should be undo-able
static char *text_hole_delete(char *p, char *q, int undo) // delete "p" through "q", inclusive
{
    char *src, *dest;
    int cnt, hole_size;

    // move forwards, from beginning
    // assume p <= q
    src = q + 1;
    dest = p;
    if (q < p) {        // they are backward- swap them
        src = p + 1;
        dest = q;
    }
    hole_size = q - p + 1;
    cnt = end - src;
#if ENABLE_FEATURE_VI_UNDO
    switch (undo) {
        case NO_UNDO:
            break;
        case ALLOW_UNDO:
            undo_push(p, hole_size, UNDO_DEL);
            break;
        case ALLOW_UNDO_CHAIN:
            undo_push(p, hole_size, UNDO_DEL_CHAIN);
            break;
# if ENABLE_FEATURE_VI_UNDO_QUEUE
        case ALLOW_UNDO_QUEUED:
            undo_push(p, hole_size, UNDO_DEL_QUEUED);
            break;
# endif
    }
    modified_count--;
#endif
    if (src < text || src > end)
        goto thd0;
    if (dest < text || dest >= end)
        goto thd0;
    modified_count++;
    if (src >= end)
        goto thd_atend; // just delete the end of the buffer
    memmove(dest, src, cnt);
 thd_atend:
    end = end - hole_size;  // adjust the new END
    if (dest >= end)
        dest = end - 1; // make sure dest in below end-1
    if (end <= text)
        dest = end = text;  // keep pointers valid
 thd0:
    return dest;
}

// copy text into register, then delete text.
//
#if !ENABLE_FEATURE_VI_UNDO
#define yank_delete(a,b,c,d,e) yank_delete(a,b,c,d)
#endif
static char *yank_delete(char *start, char *stop, int buftype, int yf, int undo)
{
    char *p;

    // make sure start <= stop
    if (start > stop) {
        // they are backwards, reverse them
        p = start;
        start = stop;
        stop = p;
    }
    if (buftype == PARTIAL && *start == '\n')
        return start;
    p = start;
#if ENABLE_FEATURE_VI_YANKMARK
    text_yank(start, stop, YDreg, buftype);
#endif
    if (yf == YANKDEL) {
        p = text_hole_delete(start, stop, undo);
    }                   // delete lines
    return p;
}

static void show_help(void)
{
    puts("These features are available:"
#if ENABLE_FEATURE_VI_SEARCH
    "\n\tPattern searches with / and ?"
#endif
#if ENABLE_FEATURE_VI_DOT_CMD
    "\n\tLast command repeat with ."
#endif
#if ENABLE_FEATURE_VI_YANKMARK
    "\n\tLine marking with 'x"
    "\n\tNamed buffers with \"x"
#endif
#if ENABLE_FEATURE_VI_READONLY
    //not implemented: "\n\tReadonly if vi is called as \"view\""
    //redundant: usage text says this too: "\n\tReadonly with -R command line arg"
#endif
#if ENABLE_FEATURE_VI_SET
    "\n\tSome colon mode commands with :"
#endif
#if ENABLE_FEATURE_VI_SETOPTS
    "\n\tSettable options with \":set\""
#endif
#if ENABLE_FEATURE_VI_USE_SIGNALS
    "\n\tSignal catching- ^C"
    "\n\tJob suspend and resume with ^Z"
#endif
#if ENABLE_FEATURE_VI_WIN_RESIZE
    "\n\tAdapt to window re-sizes"
#endif
    );
}

#if ENABLE_FEATURE_VI_DOT_CMD
static void start_new_cmd_q(char c)
{
    // get buffer for new cmd
    // if there is a current cmd count put it in the buffer first
    if (cmdcnt > 0) {
        lmc_len = sprintf(last_modifying_cmd, "%u%c", cmdcnt, c);
    } else { // just save char c onto queue
        last_modifying_cmd[0] = c;
        lmc_len = 1;
    }
    adding2q = 1;
}

static void end_cmd_q(void)
{
#if ENABLE_FEATURE_VI_YANKMARK
    YDreg = 26;         // go back to default Yank/Delete reg
#endif
    adding2q = 0;
}
#endif /* FEATURE_VI_DOT_CMD */

#if ENABLE_FEATURE_VI_YANKMARK \
 || (ENABLE_FEATURE_VI_COLON && ENABLE_FEATURE_VI_SEARCH) \
 || ENABLE_FEATURE_VI_CRASHME
// might reallocate text[]! use p += string_insert(p, ...),
// and be careful to not use pointers into potentially freed text[]!
static uintptr_t string_insert(char *p, const char *s, int undo) // insert the string at 'p'
{
    uintptr_t bias;
    int i;

    i = strlen(s);
#if ENABLE_FEATURE_VI_UNDO
    undo_push_insert(p, i, undo);
#endif
    bias = text_hole_make(p, i);
    p += bias;
    rt_memcpy(p, s, i);
#if ENABLE_FEATURE_VI_YANKMARK
    {
        int cnt;
        for (cnt = 0; *s != '\0'; s++) {
            if (*s == '\n')
                cnt++;
        }
        status_line("Put %d lines (%d chars) from [%c]", cnt, i, what_reg());
    }
#endif
    return bias;
}
#endif

//----- Block insert/delete, undo ops --------------------------
#if ENABLE_FEATURE_VI_YANKMARK
// copy text into a register
static char *text_yank(char *p, char *q, int dest, int buftype)
{
    int cnt = q - p;
    if (cnt < 0) {      // they are backwards- reverse them
        p = q;
        cnt = -cnt;
    }
    vi_free(reg[dest]);    //  if already a yank register, free it
    reg[dest] = vi_strndup(p, cnt + 1);
    return p;
}

static char what_reg(void)
{
    char c;

    c = 'D';            // default to D-reg
    if (YDreg <= 25)
        c = 'a' + (char) YDreg;
    if (YDreg == 26)
        c = 'D';
    if (YDreg == 27)
        c = 'U';
    return c;
}

static void check_context(char cmd)
{
    // A context is defined to be "modifying text"
    // Any modifying command establishes a new context.

    if (dot < context_start || dot > context_end) {
        if (strchr(modifying_cmds, cmd) != NULL) {
            // we are trying to modify text[]- make this the current context
            mark[27] = mark[26];    // move cur to prev
            mark[26] = dot; // move local to cur
            context_start = prev_line(prev_line(dot));
            context_end = next_line(next_line(dot));
            //loiter= start_loiter= now;
        }
    }
}

static char *swap_context(char *p) // goto new context for '' command make this the current context
{
    char *tmp;

    // the current context is in mark[26]
    // the previous context is in mark[27]
    // only swap context if other context is valid
    if (text <= mark[27] && mark[27] <= end - 1) {
        tmp = mark[27];
        mark[27] = mark[26];
        mark[26] = tmp;
        p = mark[26];   // where we are going- previous context
        context_start = prev_line(prev_line(prev_line(p)));
        context_end = next_line(next_line(next_line(p)));
    }
    return p;
}
#endif /* FEATURE_VI_YANKMARK */

//----- Set terminal attributes --------------------------------
static void rawmode(void)
{
#ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
    // no TERMIOS_CLEAR_ISIG: leave ISIG on - allow signals
    set_termios_to_raw(STDIN_FILENO, &term_orig, TERMIOS_RAW_CRNL);
#endif
}

static void cookmode(void)
{
    fflush_all();
#ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
    tcsetattr_stdin_TCSANOW(&term_orig);
#endif
}

#if ENABLE_FEATURE_VI_USE_SIGNALS
static void winch_handler(int sig UNUSED_PARAM)
{
    int save_errno = errno;
    // FIXME: do it in main loop!!!
    signal(SIGWINCH, winch_handler);
    query_screen_dimensions();
    new_screen(rows, columns);  // get memory for virtual screen
    redraw(TRUE);       // re-draw the screen
    errno = save_errno;
}

static void tstp_handler(int sig UNUSED_PARAM)
{
    int save_errno = errno;

    // ioctl inside cookmode() was seen to generate SIGTTOU,
    // stopping us too early. Prevent that:
    signal(SIGTTOU, SIG_IGN);

    go_bottom_and_clear_to_eol();
    cookmode(); // terminal to "cooked"

    // stop now
    //signal(SIGTSTP, SIG_DFL);
    //raise(SIGTSTP);
    raise(SIGSTOP); // avoid "dance" with TSTP handler - use SIGSTOP instead
    //signal(SIGTSTP, tstp_handler);

    // we have been "continued" with SIGCONT, restore screen and termios
    rawmode(); // terminal to "raw"
    last_status_cksum = 0; // force status update
    redraw(TRUE); // re-draw the screen

    errno = save_errno;
}

static void int_handler(int sig)
{
    signal(SIGINT, int_handler);
    siglongjmp(restart, sig);
}
#endif /* FEATURE_VI_USE_SIGNALS */

// sleep for 'h' 1/100 seconds, return 1/0 if stdin is (ready for read)/(not ready)
static int mysleep(int hund)
{
    struct pollfd pfd[1];

    if (hund != 0)
        fflush_all();

    pfd[0].fd = STDIN_FILENO;
    pfd[0].events = POLLIN;
    return safe_poll(pfd, 1, hund*10) > 0;
}

//----- IO Routines --------------------------------------------
static int readit(void) // read (maybe cursor) key from stdin
{
    int c;

    fflush_all();

    // Wait for input. TIMEOUT = -1 makes read_key wait even
    // on nonblocking stdin.
    // Note: read_key sets errno to 0 on success.
 again:
    c = read_key(STDIN_FILENO, readbuffer, /*timeout:*/ -1);
    if (c == -1) { // EOF/error
        if (errno == EAGAIN) // paranoia
            goto again;
        go_bottom_and_clear_to_eol();
        cookmode(); // terminal to "cooked"
        printf("can't read user input");
    }
    return c;
}

#if ENABLE_FEATURE_VI_DOT_CMD
static int get_one_char(void)
{
    int c;

    if (!adding2q) {
        // we are not adding to the q.
        // but, we may be reading from a saved q.
        // (checking "ioq" for NULL is wrong, it's not reset to NULL
        // when done - "ioq_start" is reset instead).
        if (ioq_start != NULL) {
            // there is a queue to get chars from.
            // careful with correct sign expansion!
            c = (unsigned char)*ioq++;
            if (c != '\0')
                return c;
            // the end of the q
            vi_free(ioq_start);
            ioq_start = NULL;
            // read from STDIN:
        }
        return readit();
    }
    // we are adding STDIN chars to q.
    c = readit();
    if (lmc_len >= ARRAY_SIZE(last_modifying_cmd) - 1) {
        // last_modifying_cmd[] is too small, can't remeber the cmd
        // - drop it
        adding2q = 0;
        lmc_len = 0;
    } else {
        last_modifying_cmd[lmc_len++] = c;
    }
    return c;
}
#else
# define get_one_char() readit()
#endif

// Get type of thing to operate on and adjust count
static int get_motion_char(void)
{
    int c, cnt;

    c = get_one_char();
    if (c != '0' && isdigit(c)) {
        // get any non-zero motion count
        for (cnt = 0; isdigit(c); c = get_one_char())
            cnt = cnt * 10 + (c - '0');
        cmdcnt = (cmdcnt ? cmdcnt : 1) * cnt;
    }

    return c;
}

// Get input line (uses "status line" area)
static char *get_input_line(const char *prompt)
{
    // char [MAX_INPUT_LEN]
#define buf get_input_line__buf

    int c;
    int i;

    strcpy(buf, prompt);
    last_status_cksum = 0;  // force status update
    go_bottom_and_clear_to_eol();
    write1(prompt);      // write out the :, /, or ? prompt

    i = strlen(buf);
    while (i < MAX_INPUT_LEN) {
        c = get_one_char();
        if (c == '\n' || c == '\r' || c == 27)
            break;      // this is end of input
        if (
            #ifdef RT_USING_POSIX_TERMIOS // RT-Thread team added
                c == term_orig.c_cc[VERASE] ||
            #endif
                c == 8 || c == 127) {
            // user wants to erase prev char
            buf[--i] = '\0';
            write1("\b \b"); // erase char on screen
            if (i <= 0) // user backs up before b-o-l, exit
                break;
        } else if (c > 0 && c < 256) { // exclude Unicode
            // (TODO: need to handle Unicode)
            buf[i] = c;
            buf[++i] = '\0';
            vi_putchar(c);
        }
    }
    refresh(FALSE);
    return buf;
#undef buf
}

// might reallocate text[]!
static int file_insert(const char *fn, char *p, int initial)
{
    int cnt = -1;
    int fd, size;
    struct stat statbuf;

    if (p < text || p > end) {
        status_line_bold("Trying to insert file outside of memory");
        return cnt;
    }

    fd = open(fn, O_RDONLY, 0);
    if (fd < 0) {
        if (!initial)
            status_line_bold_errno(fn);
        return cnt;
    }

    /* Validate file */
    if (fstat(fd, &statbuf) < 0) {
        status_line_bold_errno(fn);
        goto fi;
    }
    if (!S_ISREG(statbuf.st_mode)) {
        status_line_bold("'%s' is not a regular file", fn);
        goto fi;
    }
    size = (statbuf.st_size < INT_MAX ? (int)statbuf.st_size : INT_MAX);
    p += text_hole_make(p, size);
    cnt = full_read(fd, p, size);
    if (cnt < 0) {
        status_line_bold_errno(fn);
        p = text_hole_delete(p, p + size - 1, NO_UNDO); // un-do buffer insert
    } else if (cnt < size) {
        // There was a partial read, shrink unused space
        p = text_hole_delete(p + cnt, p + size - 1, NO_UNDO);
        status_line_bold("can't read '%s'", fn);
    }
 fi:
    close(fd);

#if ENABLE_FEATURE_VI_READONLY
    if (initial
     && ((access(fn, W_OK) < 0) ||
        /* root will always have access()
         * so we check fileperms too */
        !(statbuf.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH))
        )
    ) {
        SET_READONLY_FILE(readonly_mode);
    }
#endif
    return cnt;
}

static int file_write(char *fn, char *first, char *last)
{
    int fd, cnt, charcnt;

    if (fn == 0) {
        status_line_bold("No current filename");
        return -2;
    }
    /* By popular request we do not open file with O_TRUNC,
     * but instead ftruncate() it _after_ successful write.
     * Might reduce amount of data lost on power fail etc.
     */
//  ftruncate nosys + O_TRUNC
    fd = open(fn, (O_WRONLY | O_CREAT | O_TRUNC), 0666);
    if (fd < 0)
        return -1;
    cnt = last - first + 1;
    charcnt = full_write(fd, first, cnt);
//  ftruncate(fd, charcnt);
    if (charcnt == cnt) {
        // good write
        //modified_count = FALSE;
    } else {
        charcnt = 0;
    }
    close(fd);
    return charcnt;
}

//----- Terminal Drawing ---------------------------------------
// The terminal is made up of 'rows' line of 'columns' columns.
// classically this would be 24 x 80.
//  screen coordinates
//  0,0     ...     0,79
//  1,0     ...     1,79
//  .       ...     .
//  .       ...     .
//  22,0    ...     22,79
//  23,0    ...     23,79   <- status line

//----- Move the cursor to row x col (count from 0, not 1) -------
static void place_cursor(int row, int col)
{
    char cm1[sizeof(ESC_SET_CURSOR_POS) + sizeof(int)*3 * 2];

    if (row < 0) row = 0;
    if (row >= rows) row = rows - 1;
    if (col < 0) col = 0;
    if (col >= columns) col = columns - 1;

    sprintf(cm1, ESC_SET_CURSOR_POS, row + 1, col + 1);
    write1(cm1);
}

//----- Erase from cursor to end of line -----------------------
static void clear_to_eol(void)
{
    write1(ESC_CLEAR2EOL);
}

static void go_bottom_and_clear_to_eol(void)
{
    place_cursor(rows - 1, 0);
    clear_to_eol();
}

//----- Start standout mode ------------------------------------
static void standout_start(void)
{
    write1(ESC_BOLD_TEXT);
}

//----- End standout mode --------------------------------------
static void standout_end(void)
{
    write1(ESC_NORM_TEXT);
}

//----- Flash the screen  --------------------------------------
static void flash(int h)
{
    standout_start();
    redraw(TRUE);
    mysleep(h);
    standout_end();
    redraw(TRUE);
}

static void indicate_error(void)
{
#if ENABLE_FEATURE_VI_CRASHME
    if (crashme > 0)
        return;
#endif
    if (!err_method) {
        write1(ESC_BELL);
    } else {
        flash(10);
    }
}

//----- Screen[] Routines --------------------------------------
//----- Erase the Screen[] memory ------------------------------
static void screen_erase(void)
{
    rt_memset(screen, ' ', screensize);    // clear new screen
}

static int bufsum(char *buf, int count)
{
    int sum = 0;
    char *e = buf + count;

    while (buf < e)
        sum += (unsigned char) *buf++;
    return sum;
}

//----- Draw the status line at bottom of the screen -------------
static void show_status_line(void)
{
    int cnt = 0, cksum = 0;

    // either we already have an error or status message, or we
    // create one.
    if (!have_status_msg) {
        cnt = format_edit_status();
        cksum = bufsum(status_buffer, cnt);
    }
    if (have_status_msg || ((cnt > 0 && last_status_cksum != cksum))) {
        last_status_cksum = cksum;      // remember if we have seen this line
        go_bottom_and_clear_to_eol();
        write1(status_buffer);
        if (have_status_msg) {
            if (((int)strlen(status_buffer) - (have_status_msg - 1)) >
                    (columns - 1) ) {
                have_status_msg = 0;
                Hit_Return();
            }
            have_status_msg = 0;
        }
        place_cursor(crow, ccol);  // put cursor back in correct place
    }
    fflush_all();
}

//----- format the status buffer, the bottom line of screen ------
// format status buffer, with STANDOUT mode
static void status_line_bold(const char *format, ...)
{
    va_list args;

    va_start(args, format);
    strcpy(status_buffer, ESC_BOLD_TEXT);
    vsnprintf(status_buffer + (sizeof(ESC_BOLD_TEXT)-1),
        STATUS_BUFFER_LEN - sizeof(ESC_BOLD_TEXT) - sizeof(ESC_NORM_TEXT),
        format, args
    );
    strcat(status_buffer, ESC_NORM_TEXT);
    va_end(args);

    have_status_msg = 1 + (sizeof(ESC_BOLD_TEXT)-1) + (sizeof(ESC_NORM_TEXT)-1);
}

static void status_line_bold_errno(const char *fn)
{
    status_line_bold("'%s' %s", fn, strerror(errno));
}

//----- format the status buffer, the bottom line of screen ------
static void status_line(const char *format, ...)
{
    va_list args;

    va_start(args, format);
    vsnprintf(status_buffer, STATUS_BUFFER_LEN, format, args);
    va_end(args);

    have_status_msg = 1;
}

// copy s to buf, convert unprintable
static void print_literal(char *buf, const char *s)
{
    char *d;
    unsigned char c;

    buf[0] = '\0';
    if (!s[0])
        s = "(NULL)";

    d = buf;
    for (; *s; s++) {
        int c_is_no_print;

        c = *s;
        c_is_no_print = (c & 0x80) && !Isprint(c);
        if (c_is_no_print) {
            strcpy(d, ESC_NORM_TEXT);
            d += sizeof(ESC_NORM_TEXT)-1;
            c = '.';
        }
        if (c < ' ' || c == 0x7f) {
            *d++ = '^';
            c |= '@'; /* 0x40 */
            if (c == 0x7f)
                c = '?';
        }
        *d++ = c;
        *d = '\0';
        if (c_is_no_print) {
            strcpy(d, ESC_BOLD_TEXT);
            d += sizeof(ESC_BOLD_TEXT)-1;
        }
        if (*s == '\n') {
            *d++ = '$';
            *d = '\0';
        }
        if (d - buf > MAX_INPUT_LEN - 10) // paranoia
            break;
    }
}

static void not_implemented(const char *s)
{
    char buf[MAX_INPUT_LEN];

    print_literal(buf, s);
    status_line_bold("'%s' is not implemented", buf);
}

// show file status on status line
static int format_edit_status(void)
{
    static const char cmd_mode_indicator[] ALIGN1 = "-IR-";

#define tot format_edit_status__tot

    int cur, percent, ret, trunc_at;

    // modified_count is now a counter rather than a flag.  this
    // helps reduce the amount of line counting we need to do.
    // (this will cause a mis-reporting of modified status
    // once every MAXINT editing operations.)

    // it would be nice to do a similar optimization here -- if
    // we haven't done a motion that could have changed which line
    // we're on, then we shouldn't have to do this count_lines()
    cur = count_lines(text, dot);

    // count_lines() is expensive.
    // Call it only if something was changed since last time
    // we were here:
    if (modified_count != last_modified_count) {
        tot = cur + count_lines(dot, end - 1) - 1;
        last_modified_count = modified_count;
    }

    //    current line         percent
    //   -------------    ~~ ----------
    //    total lines            100
    if (tot > 0) {
        percent = (100 * cur) / tot;
    } else {
        cur = tot = 0;
        percent = 100;
    }

    trunc_at = columns < STATUS_BUFFER_LEN-1 ?
        columns : STATUS_BUFFER_LEN-1;

    ret = snprintf(status_buffer, trunc_at+1,
#if ENABLE_FEATURE_VI_READONLY
        "%c %s%s%s %d/%d %d%%",
#else
        "%c %s%s %d/%d %d%%",
#endif
        cmd_mode_indicator[cmd_mode & 3],
        (current_filename != NULL ? current_filename : "No file"),
#if ENABLE_FEATURE_VI_READONLY
        (readonly_mode ? " [Readonly]" : ""),
#endif
        (modified_count ? " [Modified]" : ""),
        cur, tot, percent);

    if (ret >= 0 && ret < trunc_at)
        return ret;  /* it all fit */

    return trunc_at;  /* had to truncate */
#undef tot
}

//----- Force refresh of all Lines -----------------------------
static void redraw(int full_screen)
{
    // cursor to top,left; clear to the end of screen
    write1(ESC_SET_CURSOR_TOPLEFT ESC_CLEAR2EOS);
    screen_erase();     // erase the internal screen buffer
    last_status_cksum = 0;  // force status update
    refresh(full_screen);   // this will redraw the entire display
    show_status_line();
}

//----- Format a text[] line into a buffer ---------------------
static char* format_line(char *src /*, int li*/)
{
    unsigned char c;
    int co;
    int ofs = offset;
    char *dest = scr_out_buf; // [MAX_SCR_COLS + MAX_TABSTOP * 2]

    c = '~'; // char in col 0 in non-existent lines is '~'
    co = 0;
    while (co < columns + tabstop) {
        // have we gone past the end?
        if (src < end) {
            c = *src++;
            if (c == '\n')
                break;
            if ((c & 0x80) && !Isprint(c)) {
                c = '.';
            }
            if (c < ' ' || c == 0x7f) {
                if (c == '\t') {
                    c = ' ';
                    //      co %    8     !=     7
                    while ((co % tabstop) != (tabstop - 1)) {
                        dest[co++] = c;
                    }
                } else {
                    dest[co++] = '^';
                    if (c == 0x7f)
                        c = '?';
                    else
                        c += '@'; // Ctrl-X -> 'X'
                }
            }
        }
        dest[co++] = c;
        // discard scrolled-off-to-the-left portion,
        // in tabstop-sized pieces
        if (ofs >= tabstop && co >= tabstop) {
            memmove(dest, dest + tabstop, co);
            co -= tabstop;
            ofs -= tabstop;
        }
        if (src >= end)
            break;
    }
    // check "short line, gigantic offset" case
    if (co < ofs)
        ofs = co;
    // discard last scrolled off part
    co -= ofs;
    dest += ofs;
    // fill the rest with spaces
    if (co < columns)
        rt_memset(&dest[co], ' ', columns - co);
    return dest;
}

//----- Refresh the changed screen lines -----------------------
// Copy the source line from text[] into the buffer and note
// if the current screenline is different from the new buffer.
// If they differ then that line needs redrawing on the terminal.
//
static void refresh(int full_screen)
{
#define old_offset refresh__old_offset

    int li, changed;
    char *tp, *sp;      // pointer into text[] and screen[]

    if (ENABLE_FEATURE_VI_WIN_RESIZE IF_FEATURE_VI_ASK_TERMINAL(&& !G.get_rowcol_error) ) {
        unsigned c = columns, r = rows;
        query_screen_dimensions();
#if ENABLE_FEATURE_VI_USE_SIGNALS
        full_screen |= (c - columns) | (r - rows);
#else
        if (c != columns || r != rows) {
            full_screen = TRUE;
            /* update screen memory since SIGWINCH won't have done it */
            new_screen(rows, columns);
        }
#endif
    }
    sync_cursor(dot, &crow, &ccol); // where cursor will be (on "dot")
    tp = screenbegin;   // index into text[] of top line

    // compare text[] to screen[] and mark screen[] lines that need updating
    for (li = 0; li < rows - 1; li++) {
        int cs, ce;             // column start & end
        char *out_buf;
        // format current text line
        out_buf = format_line(tp /*, li*/);

        // skip to the end of the current text[] line
        if (tp < end) {
            char *t = memchr(tp, '\n', end - tp);
            if (!t) t = end - 1;
            tp = t + 1;
        }

        // see if there are any changes between vitual screen and out_buf
        changed = FALSE;    // assume no change
        cs = 0;
        ce = columns - 1;
        sp = &screen[li * columns]; // start of screen line
        if (full_screen) {
            // force re-draw of every single column from 0 - columns-1
            goto re0;
        }
        // compare newly formatted buffer with virtual screen
        // look forward for first difference between buf and screen
        for (; cs <= ce; cs++) {
            if (out_buf[cs] != sp[cs]) {
                changed = TRUE; // mark for redraw
                break;
            }
        }

        // look backward for last difference between out_buf and screen
        for (; ce >= cs; ce--) {
            if (out_buf[ce] != sp[ce]) {
                changed = TRUE; // mark for redraw
                break;
            }
        }
        // now, cs is index of first diff, and ce is index of last diff

        // if horz offset has changed, force a redraw
        if (offset != old_offset) {
 re0:
            changed = TRUE;
        }

        // make a sanity check of columns indexes
        if (cs < 0) cs = 0;
        if (ce > columns - 1) ce = columns - 1;
        if (cs > ce) { cs = 0; ce = columns - 1; }
        // is there a change between vitual screen and out_buf
        if (changed) {
            // copy changed part of buffer to virtual screen
            rt_memcpy(sp+cs, out_buf+cs, ce-cs+1);
            place_cursor(li, cs);
            // write line out to terminal
            fwrite(&sp[cs], ce - cs + 1, 1, stdout);
        }
    }

    place_cursor(crow, ccol);

    if (!keep_index)
        cindex = ccol + offset;

    old_offset = offset;
#undef old_offset
}

//---------------------------------------------------------------------
//----- the Ascii Chart -----------------------------------------------
//  00 nul   01 soh   02 stx   03 etx   04 eot   05 enq   06 ack   07 bel
//  08 bs    09 ht    0a nl    0b vt    0c np    0d cr    0e so    0f si
//  10 dle   11 dc1   12 dc2   13 dc3   14 dc4   15 nak   16 syn   17 etb
//  18 can   19 em    1a sub   1b esc   1c fs    1d gs    1e rs    1f us
//  20 sp    21 !     22 "     23 #     24 $     25 %     26 &     27 '
//  28 (     29 )     2a *     2b +     2c ,     2d -     2e .     2f /
//  30 0     31 1     32 2     33 3     34 4     35 5     36 6     37 7
//  38 8     39 9     3a :     3b ;     3c <     3d =     3e >     3f ?
//  40 @     41 A     42 B     43 C     44 D     45 E     46 F     47 G
//  48 H     49 I     4a J     4b K     4c L     4d M     4e N     4f O
//  50 P     51 Q     52 R     53 S     54 T     55 U     56 V     57 W
//  58 X     59 Y     5a Z     5b [     5c \     5d ]     5e ^     5f _
//  60 `     61 a     62 b     63 c     64 d     65 e     66 f     67 g
//  68 h     69 i     6a j     6b k     6c l     6d m     6e n     6f o
//  70 p     71 q     72 r     73 s     74 t     75 u     76 v     77 w
//  78 x     79 y     7a z     7b {     7c |     7d }     7e ~     7f del
//---------------------------------------------------------------------

//----- Execute a Vi Command -----------------------------------
static void do_cmd(int c)
{
    char *p, *q, *save_dot;
    char buf[12];
    int dir;
    int cnt, i, j;
    int c1;

//  c1 = c; // quiet the compiler
//  cnt = yf = 0; // quiet the compiler
//  p = q = save_dot = buf; // quiet the compiler
    rt_memset(buf, '\0', sizeof(buf));
    keep_index = FALSE;

    show_status_line();

    // if this is a cursor key, skip these checks
    switch (c) {
        case KEYCODE_UP:
        case KEYCODE_DOWN:
        case KEYCODE_LEFT:
        case KEYCODE_RIGHT:
        case KEYCODE_HOME:
        case KEYCODE_END:
        case KEYCODE_PAGEUP:
        case KEYCODE_PAGEDOWN:
        case KEYCODE_DELETE:
            goto key_cmd_mode;
    }

    if (cmd_mode == 2) {
        //  flip-flop Insert/Replace mode
        if (c == KEYCODE_INSERT)
            goto dc_i;
        // we are 'R'eplacing the current *dot with new char
        if (*dot == '\n') {
            // don't Replace past E-o-l
            cmd_mode = 1;   // convert to insert
            undo_queue_commit();
        } else {
            if (1 <= c || Isprint(c)) {
                if (c != 27)
                    dot = yank_delete(dot, dot, PARTIAL, YANKDEL, ALLOW_UNDO);  // delete char
                dot = char_insert(dot, c, ALLOW_UNDO_CHAIN);    // insert new char
            }
            goto dc1;
        }
    }
    if (cmd_mode == 1) {
        // hitting "Insert" twice means "R" replace mode
        if (c == KEYCODE_INSERT) goto dc5;
        // insert the char c at "dot"
        if (1 <= c || Isprint(c)) {
            dot = char_insert(dot, c, ALLOW_UNDO_QUEUED);
        }
        goto dc1;
    }

 key_cmd_mode:
    switch (c) {
        //case 0x01:    // soh
        //case 0x09:    // ht
        //case 0x0b:    // vt
        //case 0x0e:    // so
        //case 0x0f:    // si
        //case 0x10:    // dle
        //case 0x11:    // dc1
        //case 0x13:    // dc3
#if ENABLE_FEATURE_VI_CRASHME
    case 0x14:          // dc4  ctrl-T
        crashme = (crashme == 0) ? 1 : 0;
        break;
#endif
        //case 0x16:    // syn
        //case 0x17:    // etb
        //case 0x18:    // can
        //case 0x1c:    // fs
        //case 0x1d:    // gs
        //case 0x1e:    // rs
        //case 0x1f:    // us
        //case '!': // !-
        //case '#': // #-
        //case '&': // &-
        //case '(': // (-
        //case ')': // )-
        //case '*': // *-
        //case '=': // =-
        //case '@': // @-
        //case 'K': // K-
        //case 'Q': // Q-
        //case 'S': // S-
        //case 'V': // V-
        //case '[': // [-
        //case '\\':    // \-
        //case ']': // ]-
        //case '_': // _-
        //case '`': // `-
        //case 'v': // v-
    default:            // unrecognized command
        buf[0] = c;
        buf[1] = '\0';
        not_implemented(buf);
        end_cmd_q();    // stop adding to q
    case 0x00:          // nul- ignore
        break;
    case 2:         // ctrl-B  scroll up   full screen
    case KEYCODE_PAGEUP:    // Cursor Key Page Up
        dot_scroll(rows - 2, -1);
        break;
    case 4:         // ctrl-D  scroll down half screen
        dot_scroll((rows - 2) / 2, 1);
        break;
    case 5:         // ctrl-E  scroll down one line
        dot_scroll(1, 1);
        break;
    case 6:         // ctrl-F  scroll down full screen
    case KEYCODE_PAGEDOWN:  // Cursor Key Page Down
        dot_scroll(rows - 2, 1);
        break;
    case 7:         // ctrl-G  show current status
        last_status_cksum = 0;  // force status update
        break;
    case 'h':           // h- move left
    case KEYCODE_LEFT:  // cursor key Left
    case 8:     // ctrl-H- move left    (This may be ERASE char)
    case 0x7f:  // DEL- move left   (This may be ERASE char)
        do {
            dot_left();
        } while (--cmdcnt > 0);
        break;
    case 10:            // Newline ^J
    case 'j':           // j- goto next line, same col
    case KEYCODE_DOWN:  // cursor key Down
        do {
            dot_next();     // go to next B-o-l
        } while (--cmdcnt > 0);
        // try to stay in saved column
        dot = cindex == C_END ? end_line(dot) : move_to_col(dot, cindex);
        keep_index = TRUE;
        break;
    case 12:            // ctrl-L  force redraw whole screen
    case 18:            // ctrl-R  force redraw
        redraw(TRUE);   // this will redraw the entire display
        break;
    case 13:            // Carriage Return ^M
    case '+':           // +- goto next line
        do {
            dot_next();
        } while (--cmdcnt > 0);
        dot_skip_over_ws();
        break;
    case 21:            // ctrl-U  scroll up half screen
        dot_scroll((rows - 2) / 2, -1);
        break;
    case 25:            // ctrl-Y  scroll up one line
        dot_scroll(1, -1);
        break;
    case 27:            // esc
        if (cmd_mode == 0)
            indicate_error();
        cmd_mode = 0;   // stop inserting
        undo_queue_commit();
        end_cmd_q();
        last_status_cksum = 0;  // force status update
        break;
    case ' ':           // move right
    case 'l':           // move right
    case KEYCODE_RIGHT: // Cursor Key Right
        do {
            dot_right();
        } while (--cmdcnt > 0);
        break;
#if ENABLE_FEATURE_VI_YANKMARK
    case '"':           // "- name a register to use for Delete/Yank
        c1 = (get_one_char() | 0x20) - 'a'; // | 0x20 is tolower()
        if ((unsigned)c1 <= 25) { // a-z?
            YDreg = c1;
        } else {
            indicate_error();
        }
        break;
    case '\'':          // '- goto a specific mark
        c1 = (get_one_char() | 0x20);
        if ((unsigned)(c1 - 'a') <= 25) { // a-z?
            c1 = (c1 - 'a');
            // get the b-o-l
            q = mark[c1];
            if (text <= q && q < end) {
                dot = q;
                dot_begin();    // go to B-o-l
                dot_skip_over_ws();
            }
        } else if (c1 == '\'') {    // goto previous context
            dot = swap_context(dot);    // swap current and previous context
            dot_begin();    // go to B-o-l
            dot_skip_over_ws();
        } else {
            indicate_error();
        }
        break;
    case 'm':           // m- Mark a line
        // this is really stupid.  If there are any inserts or deletes
        // between text[0] and dot then this mark will not point to the
        // correct location! It could be off by many lines!
        // Well..., at least its quick and dirty.
        c1 = (get_one_char() | 0x20) - 'a';
        if ((unsigned)c1 <= 25) { // a-z?
            // remember the line
            mark[c1] = dot;
        } else {
            indicate_error();
        }
        break;
    case 'P':           // P- Put register before
    case 'p':           // p- put register after
        p = reg[YDreg];
        if (p == NULL) {
            status_line_bold("Nothing in register %c", what_reg());
            break;
        }
        // are we putting whole lines or strings
        if (regtype[YDreg] == WHOLE) {
            if (c == 'P') {
                dot_begin();    // putting lines- Put above
            }
            if (c == 'p') {
                // are we putting after very last line?
                if (end_line(dot) == (end - 1)) {
                    dot = end;  // force dot to end of text[]
                } else {
                    dot_next(); // next line, then put before
                }
            }
        } else {
            if (c == 'p')
                dot_right();    // move to right, can move to NL
        }
        string_insert(dot, p, ALLOW_UNDO);  // insert the string
        end_cmd_q();    // stop adding to q
        break;
    case 'U':           // U- Undo; replace current line with original version
        if (reg[Ureg] != NULL) {
            p = begin_line(dot);
            q = end_line(dot);
            p = text_hole_delete(p, q, ALLOW_UNDO); // delete cur line
            p += string_insert(p, reg[Ureg], ALLOW_UNDO_CHAIN); // insert orig line
            dot = p;
            dot_skip_over_ws();
        }
        break;
#endif /* FEATURE_VI_YANKMARK */
#if ENABLE_FEATURE_VI_UNDO
    case 'u':   // u- undo last operation
        undo_pop();
        break;
#endif
    case '$':           // $- goto end of line
    case KEYCODE_END:       // Cursor Key End
        for (;;) {
            dot = end_line(dot);
            if (--cmdcnt <= 0)
                break;
            dot_next();
        }
        cindex = C_END;
        keep_index = TRUE;
        break;
    case '%':           // %- find matching char of pair () [] {}
        for (q = dot; q < end && *q != '\n'; q++) {
            if (strchr("()[]{}", *q) != NULL) {
                // we found half of a pair
                p = find_pair(q, *q);
                if (p == NULL) {
                    indicate_error();
                } else {
                    dot = p;
                }
                break;
            }
        }
        if (*q == '\n')
            indicate_error();
        break;
    case 'f':           // f- forward to a user specified char
    case 'F':           // F- backward to a user specified char
    case 't':           // t- move to char prior to next x
    case 'T':           // T- move to char after previous x
        last_search_char = get_one_char();  // get the search char
        last_search_cmd = c;
        // fall through
    case ';':           // ;- look at rest of line for last search char
    case ',':           // ,- repeat latest search in opposite direction
        dot_to_char(c != ',' ? last_search_cmd : last_search_cmd ^ 0x20);
        break;
    case '-':           // -- goto prev line
        do {
            dot_prev();
        } while (--cmdcnt > 0);
        dot_skip_over_ws();
        break;
#if ENABLE_FEATURE_VI_DOT_CMD
    case '.':           // .- repeat the last modifying command
        // Stuff the last_modifying_cmd back into stdin
        // and let it be re-executed.
        if (lmc_len != 0) {
            ioq = ioq_start = vi_strndup(last_modifying_cmd, lmc_len);
        }
        break;
#endif
#if ENABLE_FEATURE_VI_SEARCH
    case '?':           // /- search for a pattern
    case '/':           // /- search for a pattern
        buf[0] = c;
        buf[1] = '\0';
        q = get_input_line(buf);    // get input line- use "status line"
        if (q[0] && !q[1]) {
            if (last_search_pattern[0])
                last_search_pattern[0] = c;
            goto dc3; // if no pat re-use old pat
        }
        if (q[0]) {       // strlen(q) > 1: new pat- save it and find
            // there is a new pat
            vi_free(last_search_pattern);
            last_search_pattern = vi_strdup(q);
            goto dc3;   // now find the pattern
        }
        // user changed mind and erased the "/"-  do nothing
        break;
    case 'N':           // N- backward search for last pattern
        dir = BACK;     // assume BACKWARD search
        p = dot - 1;
        if (last_search_pattern[0] == '?') {
            dir = FORWARD;
            p = dot + 1;
        }
        goto dc4;       // now search for pattern
    case 'n':           // n- repeat search for last pattern
        // search rest of text[] starting at next char
        // if search fails return orignal "p" not the "p+1" address
        do {
            const char *msg;
 dc3:
            dir = FORWARD;  // assume FORWARD search
            p = dot + 1;
            if (last_search_pattern[0] == '?') {
                dir = BACK;
                p = dot - 1;
            }
 dc4:
            q = char_search(p, last_search_pattern + 1, (dir << 1) | FULL);
            if (q != NULL) {
                dot = q;    // good search, update "dot"
                msg = NULL;
                goto dc2;
            }
            // no pattern found between "dot" and "end"- continue at top
            p = text;
            if (dir == BACK) {
                p = end - 1;
            }
            q = char_search(p, last_search_pattern + 1, (dir << 1) | FULL);
            if (q != NULL) {    // found something
                dot = q;    // found new pattern- goto it
                msg = "search hit BOTTOM, continuing at TOP";
                if (dir == BACK) {
                    msg = "search hit TOP, continuing at BOTTOM";
                }
            } else {
                msg = "Pattern not found";
            }
 dc2:
            if (msg)
                status_line_bold("%s", msg);
        } while (--cmdcnt > 0);
        break;
    case '{':           // {- move backward paragraph
    case '}':           // }- move forward paragraph
        do {
            dir = c == '}' ? FORWARD : BACK;
            // skip over consecutive empty lines
            while ((dir == FORWARD ? dot < end - 1 : dot > text) &&
                        *dot == '\n' && dot[dir] == '\n') {
                dot += dir;
            }
            q = char_search(dot, "\n\n", ((unsigned)dir << 1) | FULL);
            if (q != NULL) {    // found blank line
                dot = next_line(q); // move to next blank line
            }
            else {  // blank line not found, move to end of file
                dot = dir == FORWARD ? end - 1 : text;
                break;
            }
        } while (--cmdcnt > 0);
        break;
#endif /* FEATURE_VI_SEARCH */
    case '0':           // 0- goto beginning of line
    case '1':           // 1-
    case '2':           // 2-
    case '3':           // 3-
    case '4':           // 4-
    case '5':           // 5-
    case '6':           // 6-
    case '7':           // 7-
    case '8':           // 8-
    case '9':           // 9-
        if (c == '0' && cmdcnt < 1) {
            dot_begin();    // this was a standalone zero
        } else {
            cmdcnt = cmdcnt * 10 + (c - '0');   // this 0 is part of a number
        }
        break;
    case ':':           // :- the colon mode commands
        p = get_input_line(":");    // get input line- use "status line"
        colon(p);       // execute the command
        break;
    case '<':           // <- Left  shift something
    case '>':           // >- Right shift something
        cnt = count_lines(text, dot);   // remember what line we are on
        c1 = get_motion_char(); // get the type of thing to operate on
        if (find_range(&p, &q, c1) == -1) {
            indicate_error();
            goto dc6;
        }
        yank_delete(p, q, WHOLE, YANKONLY, NO_UNDO);    // save copy before change
        p = begin_line(p);
        q = end_line(q);
        i = count_lines(p, q);  // # of lines we are shifting
        for ( ; i > 0; i--, p = next_line(p)) {
            if (c == '<') {
                // shift left- remove tab or 8 spaces
                if (*p == '\t') {
                    // shrink buffer 1 char
                    text_hole_delete(p, p, NO_UNDO);
                } else if (*p == ' ') {
                    // we should be calculating columns, not just SPACE
                    for (j = 0; *p == ' ' && j < tabstop; j++) {
                        text_hole_delete(p, p, NO_UNDO);
                    }
                }
            } else if (c == '>') {
                // shift right -- add tab or 8 spaces
                char_insert(p, '\t', ALLOW_UNDO);
            }
        }
        dot = find_line(cnt);   // what line were we on
        dot_skip_over_ws();
        end_cmd_q();    // stop adding to q
        break;
    case 'A':           // A- append at e-o-l
        dot_end();      // go to e-o-l
        //**** fall through to ... 'a'
    case 'a':           // a- append after current char
        if (*dot != '\n')
            dot++;
        goto dc_i;
    case 'B':           // B- back a blank-delimited Word
    case 'E':           // E- end of a blank-delimited word
    case 'W':           // W- forward a blank-delimited word
        dir = FORWARD;
        if (c == 'B')
            dir = BACK;
        do {
            if (c == 'W' || isspace(dot[dir])) {
                dot = skip_thing(dot, 1, dir, S_TO_WS);
                dot = skip_thing(dot, 2, dir, S_OVER_WS);
            }
            if (c != 'W')
                dot = skip_thing(dot, 1, dir, S_BEFORE_WS);
        } while (--cmdcnt > 0);
        break;
    case 'C':           // C- Change to e-o-l
    case 'D':           // D- delete to e-o-l
        save_dot = dot;
        dot = dollar_line(dot); // move to before NL
        // copy text into a register and delete
        dot = yank_delete(save_dot, dot, PARTIAL, YANKDEL, ALLOW_UNDO); // delete to e-o-l
        if (c == 'C')
            goto dc_i;  // start inserting
#if ENABLE_FEATURE_VI_DOT_CMD
        if (c == 'D')
            end_cmd_q();    // stop adding to q
#endif
        break;
    case 'g': // 'gg' goto a line number (vim) (default: very first line)
        c1 = get_one_char();
        if (c1 != 'g') {
            buf[0] = 'g';
            // c1 < 0 if the key was special. Try "g<up-arrow>"
            // TODO: if Unicode?
            buf[1] = (c1 >= 0 ? c1 : '*');
            buf[2] = '\0';
            not_implemented(buf);
            break;
        }
        if (cmdcnt == 0)
            cmdcnt = 1;
        // fall through
    case 'G':       // G- goto to a line number (default= E-O-F)
        dot = end - 1;              // assume E-O-F
        if (cmdcnt > 0) {
            dot = find_line(cmdcnt);    // what line is #cmdcnt
        }
        dot_begin();
        dot_skip_over_ws();
        break;
    case 'H':           // H- goto top line on screen
        dot = screenbegin;
        if (cmdcnt > (rows - 1)) {
            cmdcnt = (rows - 1);
        }
        if (--cmdcnt > 0) {
            do_cmd('+');
        }
        dot_skip_over_ws();
        break;
    case 'I':           // I- insert before first non-blank
        dot_begin();    // 0
        dot_skip_over_ws();
        //**** fall through to ... 'i'
    case 'i':           // i- insert before current char
    case KEYCODE_INSERT:    // Cursor Key Insert
 dc_i:
        cmd_mode = 1;   // start inserting
        undo_queue_commit();    // commit queue when cmd_mode changes
        break;
    case 'J':           // J- join current and next lines together
        do {
            dot_end();      // move to NL
            if (dot < end - 1) {    // make sure not last char in text[]
#if ENABLE_FEATURE_VI_UNDO
                undo_push(dot, 1, UNDO_DEL);
                *dot++ = ' ';   // replace NL with space
                undo_push((dot - 1), 1, UNDO_INS_CHAIN);
#else
                *dot++ = ' ';
                modified_count++;
#endif
                while (isblank(*dot)) { // delete leading WS
                    text_hole_delete(dot, dot, ALLOW_UNDO_CHAIN);
                }
            }
        } while (--cmdcnt > 0);
        end_cmd_q();    // stop adding to q
        break;
    case 'L':           // L- goto bottom line on screen
        dot = end_screen();
        if (cmdcnt > (rows - 1)) {
            cmdcnt = (rows - 1);
        }
        if (--cmdcnt > 0) {
            do_cmd('-');
        }
        dot_begin();
        dot_skip_over_ws();
        break;
    case 'M':           // M- goto middle line on screen
        dot = screenbegin;
        for (cnt = 0; cnt < (rows-1) / 2; cnt++)
            dot = next_line(dot);
        dot_skip_over_ws();
        break;
    case 'O':           // O- open a empty line above
        //    0i\n ESC -i
        p = begin_line(dot);
        if (p[-1] == '\n') {
            dot_prev();
    case 'o':           // o- open a empty line below; Yes, I know it is in the middle of the "if (..."
            dot_end();
            dot = char_insert(dot, '\n', ALLOW_UNDO);
        } else {
            dot_begin();    // 0
            dot = char_insert(dot, '\n', ALLOW_UNDO);   // i\n ESC
            dot_prev(); // -
        }
        goto dc_i;
    case 'R':           // R- continuous Replace char
 dc5:
        cmd_mode = 2;
        undo_queue_commit();
        break;
    case KEYCODE_DELETE:
        if (dot < end - 1)
            dot = yank_delete(dot, dot, PARTIAL, YANKDEL, ALLOW_UNDO);
        break;
    case 'X':           // X- delete char before dot
    case 'x':           // x- delete the current char
    case 's':           // s- substitute the current char
        dir = 0;
        if (c == 'X')
            dir = -1;
        do {
            if (dot[dir] != '\n') {
                if (c == 'X')
                    dot--;  // delete prev char
                dot = yank_delete(dot, dot, PARTIAL, YANKDEL, ALLOW_UNDO);  // delete char
            }
        } while (--cmdcnt > 0);
        end_cmd_q();    // stop adding to q
        if (c == 's')
            goto dc_i;  // start inserting
        break;
    case 'Z':           // Z- if modified, {write}; exit
        // ZZ means to save file (if necessary), then exit
        c1 = get_one_char();
        if (c1 != 'Z') {
            indicate_error();
            break;
        }
        if (modified_count) {
            if (ENABLE_FEATURE_VI_READONLY && readonly_mode) {
                status_line_bold("'%s' is read only", current_filename);
                break;
            }
            cnt = file_write(current_filename, text, end - 1);
            if (cnt < 0) {
                if (cnt == -1)
                    status_line_bold("Write error: %s", strerror(errno));
            } else if (cnt == (end - 1 - text + 1)) {
                editing = 0;
            }
        } else {
            editing = 0;
        }
        break;
    case '^':           // ^- move to first non-blank on line
        dot_begin();
        dot_skip_over_ws();
        break;
    case 'b':           // b- back a word
    case 'e':           // e- end of word
        dir = FORWARD;
        if (c == 'b')
            dir = BACK;
        do {
            if ((dot + dir) < text || (dot + dir) > end - 1)
                break;
            dot += dir;
            if (isspace(*dot)) {
                dot = skip_thing(dot, (c == 'e') ? 2 : 1, dir, S_OVER_WS);
            }
            if (isalnum(*dot) || *dot == '_') {
                dot = skip_thing(dot, 1, dir, S_END_ALNUM);
            } else if (ispunct(*dot)) {
                dot = skip_thing(dot, 1, dir, S_END_PUNCT);
            }
        } while (--cmdcnt > 0);
        break;
    case 'c':           // c- change something
    case 'd':           // d- delete something
#if ENABLE_FEATURE_VI_YANKMARK
    case 'y':           // y- yank   something
    case 'Y':           // Y- Yank a line
#endif
    {
#if ENABLE_FEATURE_VI_YANKMARK
        char *savereg = reg[YDreg];
#endif
        int yf, buftype = 0;
        yf = YANKDEL;   // assume either "c" or "d"
#if ENABLE_FEATURE_VI_YANKMARK
        if (c == 'y' || c == 'Y')
            yf = YANKONLY;
#endif
        c1 = 'y';
        if (c != 'Y') {
            c1 = get_motion_char(); // get the type of thing to operate on
            if (c1 == 27)   // ESC- user changed mind and wants out
                goto dc6;
        }
        // determine range, and whether it spans lines
        buftype = find_range(&p, &q, c1);
        place_cursor(0, 0);
        if (buftype == -1) { // invalid range
            indicate_error();
            goto dc6;
        }
        if (c1 == 'w' || c1 == 'W') {
            char *q0 = q;
            // don't include trailing WS as part of word
            while (q > p && isspace(*q)) {
                if (*q-- == '\n')
                    q0 = q;
            }
            // for non-change operations WS after NL is not part of word
            if (c != 'c' && q != p && *q != '\n')
                q = q0;
        }
        dot = yank_delete(p, q, buftype, yf, ALLOW_UNDO);   // delete word
        if (buftype == WHOLE) {
            if (c == 'c') {
                dot = char_insert(dot, '\n', ALLOW_UNDO_CHAIN);
                // on the last line of file don't move to prev line
                if (dot != (end-1)) {
                    dot_prev();
                }
            } else if (c == 'd') {
                dot_begin();
                dot_skip_over_ws();
            }
        }
        // if CHANGING, not deleting, start inserting after the delete
        if (c == 'c') {
            //strcpy(buf, "Change");
            goto dc_i;  // start inserting
        }
#if ENABLE_FEATURE_VI_YANKMARK
        // only update status if a yank has actually happened
        if (reg[YDreg] != savereg) {
            if (c == 'd') {
                strcpy(buf, "Delete");
            }
            if (c == 'y' || c == 'Y') {
                strcpy(buf, "Yank");
            }
            p = reg[YDreg];
            q = p + strlen(p);
            for (cnt = 0; p <= q; p++) {
                if (*p == '\n')
                    cnt++;
            }
            status_line("%s %u lines (%u chars) using [%c]",
                buf, cnt, (unsigned)strlen(reg[YDreg]), what_reg());
        }
#endif
 dc6:
        end_cmd_q();    // stop adding to q
        break;
    }
    case 'k':           // k- goto prev line, same col
    case KEYCODE_UP:        // cursor key Up
        do {
            dot_prev();
        } while (--cmdcnt > 0);
        // try to stay in saved column
        dot = cindex == C_END ? end_line(dot) : move_to_col(dot, cindex);
        keep_index = TRUE;
        break;
    case 'r':           // r- replace the current char with user input
        c1 = get_one_char();    // get the replacement char
        if (*dot != '\n') {
            dot = text_hole_delete(dot, dot, ALLOW_UNDO);
            dot = char_insert(dot, c1, ALLOW_UNDO_CHAIN);
            dot_left();
        }
        end_cmd_q();    // stop adding to q
        break;
    case 'w':           // w- forward a word
        do {
            if (isalnum(*dot) || *dot == '_') { // we are on ALNUM
                dot = skip_thing(dot, 1, FORWARD, S_END_ALNUM);
            } else if (ispunct(*dot)) { // we are on PUNCT
                dot = skip_thing(dot, 1, FORWARD, S_END_PUNCT);
            }
            if (dot < end - 1)
                dot++;      // move over word
            if (isspace(*dot)) {
                dot = skip_thing(dot, 2, FORWARD, S_OVER_WS);
            }
        } while (--cmdcnt > 0);
        break;
    case 'z':           // z-
        c1 = get_one_char();    // get the replacement char
        cnt = 0;
        if (c1 == '.')
            cnt = (rows - 2) / 2;   // put dot at center
        if (c1 == '-')
            cnt = rows - 2; // put dot at bottom
        screenbegin = begin_line(dot);  // start dot at top
        dot_scroll(cnt, -1);
        break;
    case '|':           // |- move to column "cmdcnt"
        dot = move_to_col(dot, cmdcnt - 1); // try to move to column
        break;
    case '~':           // ~- flip the case of letters   a-z -> A-Z
        do {
#if ENABLE_FEATURE_VI_UNDO
            if (islower(*dot)) {
                undo_push(dot, 1, UNDO_DEL);
                *dot = toupper(*dot);
                undo_push(dot, 1, UNDO_INS_CHAIN);
            } else if (isupper(*dot)) {
                undo_push(dot, 1, UNDO_DEL);
                *dot = tolower(*dot);
                undo_push(dot, 1, UNDO_INS_CHAIN);
            }
#else
            if (islower(*dot)) {
                *dot = toupper(*dot);
                modified_count++;
            } else if (isupper(*dot)) {
                *dot = tolower(*dot);
                modified_count++;
            }
#endif
            dot_right();
        } while (--cmdcnt > 0);
        end_cmd_q();    // stop adding to q
        break;
        //----- The Cursor and Function Keys -----------------------------
    case KEYCODE_HOME:  // Cursor Key Home
        dot_begin();
        break;
        // The Fn keys could point to do_macro which could translate them
#if 0
    case KEYCODE_FUN1:  // Function Key F1
    case KEYCODE_FUN2:  // Function Key F2
    case KEYCODE_FUN3:  // Function Key F3
    case KEYCODE_FUN4:  // Function Key F4
    case KEYCODE_FUN5:  // Function Key F5
    case KEYCODE_FUN6:  // Function Key F6
    case KEYCODE_FUN7:  // Function Key F7
    case KEYCODE_FUN8:  // Function Key F8
    case KEYCODE_FUN9:  // Function Key F9
    case KEYCODE_FUN10: // Function Key F10
    case KEYCODE_FUN11: // Function Key F11
    case KEYCODE_FUN12: // Function Key F12
        break;
#endif
    }

 dc1:
    // if text[] just became empty, add back an empty line
    if (end == text) {
        char_insert(text, '\n', NO_UNDO);   // start empty buf with dummy line
        dot = text;
    }
    // it is OK for dot to exactly equal to end, otherwise check dot validity
    if (dot != end) {
        dot = bound_dot(dot);   // make sure "dot" is valid
    }
#if ENABLE_FEATURE_VI_YANKMARK
    check_context(c);   // update the current context
#endif

    if (!isdigit(c))
        cmdcnt = 0;     // cmd was not a number, reset cmdcnt
    cnt = dot - begin_line(dot);
    // Try to stay off of the Newline
    if (*dot == '\n' && cnt > 0 && cmd_mode == 0)
        dot--;
}

/* NB!  the CRASHME code is unmaintained, and doesn't currently build */
#if ENABLE_FEATURE_VI_CRASHME
static int totalcmds = 0;
static int Mp = 85;             // Movement command Probability
static int Np = 90;             // Non-movement command Probability
static int Dp = 96;             // Delete command Probability
static int Ip = 97;             // Insert command Probability
static int Yp = 98;             // Yank command Probability
static int Pp = 99;             // Put command Probability
static int M = 0, N = 0, I = 0, D = 0, Y = 0, P = 0, U = 0;
static const char chars[20] = "\t012345 abcdABCD-=.$";
static const char *const words[20] = {
    "this", "is", "a", "test",
    "broadcast", "the", "emergency", "of",
    "system", "quick", "brown", "fox",
    "jumped", "over", "lazy", "dogs",
    "back", "January", "Febuary", "March"
};
static const char *const lines[20] = {
    "You should have received a copy of the GNU General Public License\n",
    "char c, cm, *cmd, *cmd1;\n",
    "generate a command by percentages\n",
    "Numbers may be typed as a prefix to some commands.\n",
    "Quit, discarding changes!\n",
    "Forced write, if permission originally not valid.\n",
    "In general, any ex or ed command (such as substitute or delete).\n",
    "I have tickets available for the Blazers vs LA Clippers for Monday, Janurary 1 at 1:00pm.\n",
    "Please get w/ me and I will go over it with you.\n",
    "The following is a list of scheduled, committed changes.\n",
    "1.   Launch Norton Antivirus (Start, Programs, Norton Antivirus)\n",
    "Reminder....Town Meeting in Central Perk cafe today at 3:00pm.\n",
    "Any question about transactions please contact Sterling Huxley.\n",
    "I will try to get back to you by Friday, December 31.\n",
    "This Change will be implemented on Friday.\n",
    "Let me know if you have problems accessing this;\n",
    "Sterling Huxley recently added you to the access list.\n",
    "Would you like to go to lunch?\n",
    "The last command will be automatically run.\n",
    "This is too much english for a computer geek.\n",
};
static char *multilines[20] = {
    "You should have received a copy of the GNU General Public License\n",
    "char c, cm, *cmd, *cmd1;\n",
    "generate a command by percentages\n",
    "Numbers may be typed as a prefix to some commands.\n",
    "Quit, discarding changes!\n",
    "Forced write, if permission originally not valid.\n",
    "In general, any ex or ed command (such as substitute or delete).\n",
    "I have tickets available for the Blazers vs LA Clippers for Monday, Janurary 1 at 1:00pm.\n",
    "Please get w/ me and I will go over it with you.\n",
    "The following is a list of scheduled, committed changes.\n",
    "1.   Launch Norton Antivirus (Start, Programs, Norton Antivirus)\n",
    "Reminder....Town Meeting in Central Perk cafe today at 3:00pm.\n",
    "Any question about transactions please contact Sterling Huxley.\n",
    "I will try to get back to you by Friday, December 31.\n",
    "This Change will be implemented on Friday.\n",
    "Let me know if you have problems accessing this;\n",
    "Sterling Huxley recently added you to the access list.\n",
    "Would you like to go to lunch?\n",
    "The last command will be automatically run.\n",
    "This is too much english for a computer geek.\n",
};

// create a random command to execute
static void crash_dummy()
{
    static int sleeptime;   // how long to pause between commands
    char c, cm, *cmd, *cmd1;
    int i, cnt, thing, rbi, startrbi, percent;

    // "dot" movement commands
    cmd1 = " \n\r\002\004\005\006\025\0310^$-+wWeEbBhjklHL";

    // is there already a command running?
    if (readbuffer[0] > 0)
        goto cd1;
 cd0:
    readbuffer[0] = 'X';
    startrbi = rbi = 1;
    sleeptime = 0;          // how long to pause between commands
    rt_memset(readbuffer, '\0', sizeof(readbuffer));
    // generate a command by percentages
    percent = (int) lrand48() % 100;        // get a number from 0-99
    if (percent < Mp) {     //  Movement commands
        // available commands
        cmd = cmd1;
        M++;
    } else if (percent < Np) {      //  non-movement commands
        cmd = "mz<>\'\"";       // available commands
        N++;
    } else if (percent < Dp) {      //  Delete commands
        cmd = "dx";             // available commands
        D++;
    } else if (percent < Ip) {      //  Inset commands
        cmd = "iIaAsrJ";        // available commands
        I++;
    } else if (percent < Yp) {      //  Yank commands
        cmd = "yY";             // available commands
        Y++;
    } else if (percent < Pp) {      //  Put commands
        cmd = "pP";             // available commands
        P++;
    } else {
        // We do not know how to handle this command, try again
        U++;
        goto cd0;
    }
    // randomly pick one of the available cmds from "cmd[]"
    i = (int) lrand48() % strlen(cmd);
    cm = cmd[i];
    if (strchr(":\024", cm))
        goto cd0;               // dont allow colon or ctrl-T commands
    readbuffer[rbi++] = cm; // put cmd into input buffer

    // now we have the command-
    // there are 1, 2, and multi char commands
    // find out which and generate the rest of command as necessary
    if (strchr("dmryz<>\'\"", cm)) {        // 2-char commands
        cmd1 = " \n\r0$^-+wWeEbBhjklHL";
        if (cm == 'm' || cm == '\'' || cm == '\"') {    // pick a reg[]
            cmd1 = "abcdefghijklmnopqrstuvwxyz";
        }
        thing = (int) lrand48() % strlen(cmd1); // pick a movement command
        c = cmd1[thing];
        readbuffer[rbi++] = c;  // add movement to input buffer
    }
    if (strchr("iIaAsc", cm)) {     // multi-char commands
        if (cm == 'c') {
            // change some thing
            thing = (int) lrand48() % strlen(cmd1); // pick a movement command
            c = cmd1[thing];
            readbuffer[rbi++] = c;  // add movement to input buffer
        }
        thing = (int) lrand48() % 4;    // what thing to insert
        cnt = (int) lrand48() % 10;     // how many to insert
        for (i = 0; i < cnt; i++) {
            if (thing == 0) {       // insert chars
                readbuffer[rbi++] = chars[((int) lrand48() % strlen(chars))];
            } else if (thing == 1) {        // insert words
                strcat(readbuffer, words[(int) lrand48() % 20]);
                strcat(readbuffer, " ");
                sleeptime = 0;  // how fast to type
            } else if (thing == 2) {        // insert lines
                strcat(readbuffer, lines[(int) lrand48() % 20]);
                sleeptime = 0;  // how fast to type
            } else {        // insert multi-lines
                strcat(readbuffer, multilines[(int) lrand48() % 20]);
                sleeptime = 0;  // how fast to type
            }
        }
        strcat(readbuffer, "\033");
    }
    readbuffer[0] = strlen(readbuffer + 1);
 cd1:
    totalcmds++;
    if (sleeptime > 0)
        mysleep(sleeptime);      // sleep 1/100 sec
}

// test to see if there are any errors
static void crash_test()
{
    static time_t oldtim;

    time_t tim;
    char d[2], msg[80];

    msg[0] = '\0';
    if (end < text) {
        strcat(msg, "end<text ");
    }
    if (end > textend) {
        strcat(msg, "end>textend ");
    }
    if (dot < text) {
        strcat(msg, "dot<text ");
    }
    if (dot > end) {
        strcat(msg, "dot>end ");
    }
    if (screenbegin < text) {
        strcat(msg, "screenbegin<text ");
    }
    if (screenbegin > end - 1) {
        strcat(msg, "screenbegin>end-1 ");
    }

    if (msg[0]) {
        printf("\n\n%d: \'%c\' %s\n\n\n%s[Hit return to continue]%s",
            totalcmds, last_input_char, msg, ESC_BOLD_TEXT, ESC_NORM_TEXT);
        fflush_all();
        while (safe_read(STDIN_FILENO, d, 1) > 0) {
            if (d[0] == '\n' || d[0] == '\r')
                break;
        }
    }
    tim = time(NULL);
    if (tim >= (oldtim + 3)) {
        sprintf(status_buffer,
                "Tot=%d: M=%d N=%d I=%d D=%d Y=%d P=%d U=%d size=%d",
                totalcmds, M, N, I, D, Y, P, U, end - text + 1);
        oldtim = tim;
    }
}
#endif