// Copyright 2015-2020 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "soc/uart_periph.h"
#include "soc/gpio_periph.h"
#include "soc/soc.h"
#include "soc/usb_serial_jtag_struct.h"
#include "hal/usb_serial_jtag_ll.h"
#include "esp_gdbstub_common.h"
#include "sdkconfig.h"

#define UART_NUM CONFIG_ESP_CONSOLE_UART_NUM

#define GDBSTUB_MEM_REGION_COUNT 9

#define UART_REG_FIELD_LEN 0x84

typedef struct {
    intptr_t lower;
    intptr_t upper;
} mem_bound_t;

static const mem_bound_t mem_region_table [GDBSTUB_MEM_REGION_COUNT] =
{
    {SOC_DROM_LOW, SOC_DROM_HIGH},
    {SOC_IROM_LOW, SOC_IROM_HIGH},
    {SOC_IRAM_LOW, SOC_IRAM_HIGH},
    {SOC_DRAM_LOW, SOC_DRAM_HIGH},
    {SOC_IROM_MASK_LOW, SOC_IROM_MASK_HIGH},
    {SOC_DROM_MASK_LOW, SOC_DROM_MASK_HIGH},
    {SOC_RTC_IRAM_LOW, SOC_RTC_IRAM_HIGH},
    // RTC DRAM and RTC DATA are identical with RTC IRAM, hence we skip them
    // We shouldn't read the uart registers since it will disturb the debugging via UART,
    // so skip UART part of the peripheral registers.
    {DR_REG_UART_BASE + UART_REG_FIELD_LEN, SOC_PERIPHERAL_HIGH},
    {SOC_DEBUG_LOW, SOC_DEBUG_HIGH},
};

static inline bool check_inside_valid_region(intptr_t addr)
{
    for (size_t i = 0; i < GDBSTUB_MEM_REGION_COUNT; i++) {
        if (addr >= mem_region_table[i].lower && addr < mem_region_table[i].upper) {
            return true;
        }
    }

    return false;
}

void esp_gdbstub_target_init()
{
}

#if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG

int esp_gdbstub_getchar()
{
    uint8_t c;
    //retry the read until we succeed
    while (usb_serial_jtag_ll_read_rxfifo(&c, 1)==0) ;
    return c;
}

void esp_gdbstub_putchar(int c)
{
    uint8_t cc=c;
    //retry the write until we succeed
    while (usb_serial_jtag_ll_write_txfifo(&cc, 1)<1) ;
}

void esp_gdbstub_flush()
{
    usb_serial_jtag_ll_txfifo_flush();
}


#else

//assume UART gdbstub channel

int esp_gdbstub_getchar()
{
    while (REG_GET_FIELD(UART_STATUS_REG(UART_NUM), UART_RXFIFO_CNT) == 0) {
        ;
    }
    return REG_READ(UART_FIFO_AHB_REG(UART_NUM));
}

void esp_gdbstub_putchar(int c)
{
    while (REG_GET_FIELD(UART_STATUS_REG(UART_NUM), UART_TXFIFO_CNT) >= 126) {
        ;
    }
    REG_WRITE(UART_FIFO_AHB_REG(UART_NUM), c);
}

void esp_gdbstub_flush()
{
    //not needed for uart
}

#endif

int esp_gdbstub_readmem(intptr_t addr)
{
    if (!check_inside_valid_region(addr)) {
        /* see esp_cpu_configure_region_protection */
        return -1;
    }
    uint32_t val_aligned = *(uint32_t *)(addr & (~3));
    uint32_t shift = (addr & 3) * 8;
    return (val_aligned >> shift) & 0xff;
}
