quicklz/quicklz.c

// Fast data compression library
// Copyright (C) 2006-2011 Lasse Mikkel Reinhold
// lar@quicklz.com
//
// QuickLZ can be used for free under the GPL 1, 2 or 3 license (where anything
// released into public must be open source) or under a commercial license if such
// has been acquired (see http://www.quicklz.com/order.html). The commercial license
// does not cover derived or ported versions created by third parties under GPL.

// 1.5.0 final

#include "quicklz.h"

#if QLZ_VERSION_MAJOR != 1 || QLZ_VERSION_MINOR != 5 || QLZ_VERSION_REVISION != 0
#error quicklz.c and quicklz.h have different versions
#endif

#if (defined(__X86__) || defined(__i386__) || defined(i386) || defined(_M_IX86) || defined(__386__) || defined(__x86_64__) || defined(_M_X64))
#define X86X64
#endif

#define MINOFFSET 2
#define UNCONDITIONAL_MATCHLEN 6
#define UNCOMPRESSED_END 4
#define CWORD_LEN 4

#if QLZ_COMPRESSION_LEVEL == 1 && defined QLZ_PTR_64 && QLZ_STREAMING_BUFFER == 0
#define OFFSET_BASE source
#define CAST (ui32)(size_t)
#else
#define OFFSET_BASE 0
#define CAST
#endif

int qlz_get_setting(int setting)
{
    switch(setting)
    {
        case 0:
            return QLZ_COMPRESSION_LEVEL;
        case 1:
            return sizeof(qlz_state_compress);
        case 2:
            return sizeof(qlz_state_decompress);
        case 3:
            return QLZ_STREAMING_BUFFER;
#ifdef QLZ_MEMORY_SAFE
        case 6:
            return 1;
#else
        case 6:
            return 0;
#endif
        case 7:
            return QLZ_VERSION_MAJOR;
        case 8:
            return QLZ_VERSION_MINOR;
        case 9:
            return QLZ_VERSION_REVISION;
    }
    return -1;
}

#if QLZ_COMPRESSION_LEVEL == 1
static int same(const unsigned char *src, size_t n)
{
    while(n > 0 && *(src + n) == *src)
        n--;
    return n == 0 ? 1 : 0;
}
#endif

static void reset_table_compress(qlz_state_compress *state)
{
    int i;
    for(i = 0; i < QLZ_HASH_VALUES; i++)
    {
#if QLZ_COMPRESSION_LEVEL == 1
        state->hash[i].offset = 0;
#else
        state->hash_counter[i] = 0;
#endif
    }
}

static void reset_table_decompress(qlz_state_decompress *state)
{
    int i;
    (void)state;
    (void)i;
#if QLZ_COMPRESSION_LEVEL == 2
    for(i = 0; i < QLZ_HASH_VALUES; i++)
    {
        state->hash_counter[i] = 0;
    }
#endif
}

static __inline ui32 hash_func(ui32 i)
{
#if QLZ_COMPRESSION_LEVEL == 2
    return ((i >> 9) ^ (i >> 13) ^ i) & (QLZ_HASH_VALUES - 1);
#else
    return ((i >> 12) ^ i) & (QLZ_HASH_VALUES - 1);
#endif
}

static __inline ui32 fast_read(void const *src, ui32 bytes)
{
#ifndef X86X64
    unsigned char *p = (unsigned char *)src;
    switch(bytes)
    {
        case 4:
            return(*p | *(p + 1) << 8 | *(p + 2) << 16 | *(p + 3) << 24);
        case 3:
            return(*p | *(p + 1) << 8 | *(p + 2) << 16);
        case 2:
            return(*p | *(p + 1) << 8);
        case 1:
            return(*p);
    }
    return 0;
#else
    if(bytes >= 1 && bytes <= 4)
        return *((ui32 *)src);
    else
        return 0;
#endif
}

static __inline ui32 hashat(const unsigned char *src)
{
    ui32 fetch, hash;
    fetch = fast_read(src, 3);
    hash = hash_func(fetch);
    return hash;
}

static __inline void fast_write(ui32 f, void *dst, size_t bytes)
{
#ifndef X86X64
    unsigned char *p = (unsigned char *)dst;

    switch(bytes)
    {
        case 4:
            *p = (unsigned char)f;
            *(p + 1) = (unsigned char)(f >> 8);
            *(p + 2) = (unsigned char)(f >> 16);
            *(p + 3) = (unsigned char)(f >> 24);
            return;
        case 3:
            *p = (unsigned char)f;
            *(p + 1) = (unsigned char)(f >> 8);
            *(p + 2) = (unsigned char)(f >> 16);
            return;
        case 2:
            *p = (unsigned char)f;
            *(p + 1) = (unsigned char)(f >> 8);
            return;
        case 1:
            *p = (unsigned char)f;
            return;
    }
#else
    switch(bytes)
    {
        case 4:
            *((ui32 *)dst) = f;
            return;
        case 3:
            *((ui32 *)dst) = f;
            return;
        case 2:
            *((ui16 *)dst) = (ui16)f;
            return;
        case 1:
            *((unsigned char *)dst) = (unsigned char)f;
            return;
    }
#endif
}


size_t qlz_size_decompressed(const char *source)
{
    ui32 n, r;
    n = (((*source) & 2) == 2) ? 4 : 1;
    r = fast_read(source + 1 + n, n);
    r = r & (0xffffffff >> ((4 - n) * 8));
    return r;
}

size_t qlz_size_compressed(const char *source)
{
    ui32 n, r;
    n = (((*source) & 2) == 2) ? 4 : 1;
    r = fast_read(source + 1, n);
    r = r & (0xffffffff >> ((4 - n) * 8));
    return r;
}

size_t qlz_size_header(const char *source)
{
    size_t n = 2 * ((((*source) & 2) == 2) ? 4 : 1) + 1;
    return n;
}


static __inline void memcpy_up(unsigned char *dst, const unsigned char *src, ui32 n)
{
    // Caution if modifying memcpy_up! Overlap of dst and src must be special handled.
#ifndef X86X64
    unsigned char *end = dst + n;
    while(dst < end)
    {
        *dst = *src;
        dst++;
        src++;
    }
#else
    ui32 f = 0;
    do
    {
        *(ui32 *)(dst + f) = *(ui32 *)(src + f);
        f += MINOFFSET + 1;
    }
    while(f < n);
#endif
}

static __inline void update_hash(qlz_state_decompress *state, const unsigned char *s)
{
#if QLZ_COMPRESSION_LEVEL == 1
    ui32 hash;
    hash = hashat(s);
    state->hash[hash].offset = s;
    state->hash_counter[hash] = 1;
#elif QLZ_COMPRESSION_LEVEL == 2
    ui32 hash;
    unsigned char c;
    hash = hashat(s);
    c = state->hash_counter[hash];
    state->hash[hash].offset[c & (QLZ_POINTERS - 1)] = s;
    c++;
    state->hash_counter[hash] = c;
#endif
    (void)state;
    (void)s;
}

#if QLZ_COMPRESSION_LEVEL <= 2
static void update_hash_upto(qlz_state_decompress *state, unsigned char **lh, const unsigned char *max)
{
    while(*lh < max)
    {
        (*lh)++;
        update_hash(state, *lh);
    }
}
#endif

static size_t qlz_compress_core(const unsigned char *source, unsigned char *destination, size_t size, qlz_state_compress *state)
{
    const unsigned char *last_byte = source + size - 1;
    const unsigned char *src = source;
    unsigned char *cword_ptr = destination;
    unsigned char *dst = destination + CWORD_LEN;
    ui32 cword_val = 1U << 31;
    const unsigned char *last_matchstart = last_byte - UNCONDITIONAL_MATCHLEN - UNCOMPRESSED_END;
    ui32 fetch = 0;
    unsigned int lits = 0;

    (void) lits;

    if(src <= last_matchstart)
        fetch = fast_read(src, 3);

    while(src <= last_matchstart)
    {
        if((cword_val & 1) == 1)
        {
            // store uncompressed if compression ratio is too low
            if(src > source + (size >> 1) && dst - destination > src - source - ((src - source) >> 5))
                return 0;

            fast_write((cword_val >> 1) | (1U << 31), cword_ptr, CWORD_LEN);

            cword_ptr = dst;
            dst += CWORD_LEN;
            cword_val = 1U << 31;
            fetch = fast_read(src, 3);
        }
#if QLZ_COMPRESSION_LEVEL == 1
        {
            const unsigned char *o;
            ui32 hash, cached;

            hash = hash_func(fetch);
            cached = fetch ^ state->hash[hash].cache;
            state->hash[hash].cache = fetch;

            o = state->hash[hash].offset + OFFSET_BASE;
            state->hash[hash].offset = CAST(src - OFFSET_BASE);

#ifdef X86X64
            if((cached & 0xffffff) == 0 && o != OFFSET_BASE && (src - o > MINOFFSET || (src == o + 1 && lits >= 3 && src > source + 3 && same(src - 3, 6))))
            {
                if(cached != 0)
                {
#else
            if(cached == 0 && o != OFFSET_BASE && (src - o > MINOFFSET || (src == o + 1 && lits >= 3 && src > source + 3 && same(src - 3, 6))))
            {
                if(*(o + 3) != *(src + 3))
                {
#endif
                    hash <<= 4;
                    cword_val = (cword_val >> 1) | (1U << 31);
                    fast_write((3 - 2) | hash, dst, 2);
                    src += 3;
                    dst += 2;
                }
                else
                {
                    const unsigned char *old_src = src;
                    size_t matchlen;
                    hash <<= 4;

                    cword_val = (cword_val >> 1) | (1U << 31);
                    src += 4;

                    if(*(o + (src - old_src)) == *src)
                    {
                        src++;
                        if(*(o + (src - old_src)) == *src)
                        {
                            size_t q = last_byte - UNCOMPRESSED_END - (src - 5) + 1;
                            size_t remaining = q > 255 ? 255 : q;
                            src++;
                            while(*(o + (src - old_src)) == *src && (size_t)(src - old_src) < remaining)
                                src++;
                        }
                    }

                    matchlen = src - old_src;
                    if(matchlen < 18)
                    {
                        fast_write((ui32)(matchlen - 2) | hash, dst, 2);
                        dst += 2;
                    }
                    else
                    {
                        fast_write((ui32)(matchlen << 16) | hash, dst, 3);
                        dst += 3;
                    }
                }
                fetch = fast_read(src, 3);
                lits = 0;
            }
            else
            {
                lits++;
                *dst = *src;
                src++;
                dst++;
                cword_val = (cword_val >> 1);
#ifdef X86X64
                fetch = fast_read(src, 3);
#else
                fetch = (fetch >> 8 & 0xffff) | (*(src + 2) << 16);
#endif
            }
        }
#elif QLZ_COMPRESSION_LEVEL >= 2
        {
            const unsigned char *o, *offset2;
            ui32 hash, matchlen, k, m, best_k = 0;
            unsigned char c;
            size_t remaining = (last_byte - UNCOMPRESSED_END - src + 1) > 255 ? 255 : (last_byte - UNCOMPRESSED_END - src + 1);
            (void)best_k;


            //hash = hashat(src);
            fetch = fast_read(src, 3);
            hash = hash_func(fetch);

            c = state->hash_counter[hash];

            offset2 = state->hash[hash].offset[0];
            if(offset2 < src - MINOFFSET && c > 0 && ((fast_read(offset2, 3) ^ fetch) & 0xffffff) == 0)
            {
                matchlen = 3;
                if(*(offset2 + matchlen) == *(src + matchlen))
                {
                    matchlen = 4;
                    while(*(offset2 + matchlen) == *(src + matchlen) && matchlen < remaining)
                        matchlen++;
                }
            }
            else
                matchlen = 0;
            for(k = 1; k < QLZ_POINTERS && c > k; k++)
            {
                o = state->hash[hash].offset[k];
#if QLZ_COMPRESSION_LEVEL == 3
                if(((fast_read(o, 3) ^ fetch) & 0xffffff) == 0 && o < src - MINOFFSET)
#elif QLZ_COMPRESSION_LEVEL == 2
                if(*(src + matchlen) == *(o + matchlen) && ((fast_read(o, 3) ^ fetch) & 0xffffff) == 0 && o < src - MINOFFSET)
#endif
                {
                    m = 3;
                    while(*(o + m) == *(src + m) && m < remaining)
                        m++;
#if QLZ_COMPRESSION_LEVEL == 3
                    if((m > matchlen) || (m == matchlen && o > offset2))
#elif QLZ_COMPRESSION_LEVEL == 2
                    if(m > matchlen)
#endif
                    {
                        offset2 = o;
                        matchlen = m;
                        best_k = k;
                    }
                }
            }
            o = offset2;
            state->hash[hash].offset[c & (QLZ_POINTERS - 1)] = src;
            c++;
            state->hash_counter[hash] = c;

#if QLZ_COMPRESSION_LEVEL == 3
            if(matchlen > 2 && src - o < 131071)
            {
                ui32 u;
                size_t offset = src - o;

                for(u = 1; u < matchlen; u++)
                {
                    hash = hashat(src + u);
                    c = state->hash_counter[hash]++;
                    state->hash[hash].offset[c & (QLZ_POINTERS - 1)] = src + u;
                }

                cword_val = (cword_val >> 1) | (1U << 31);
                src += matchlen;

                if(matchlen == 3 && offset <= 63)
                {
                    *dst = (unsigned char)(offset << 2);
                    dst++;
                }
                else if(matchlen == 3 && offset <= 16383)
                {
                    ui32 f = (ui32)((offset << 2) | 1);
                    fast_write(f, dst, 2);
                    dst += 2;
                }
                else if(matchlen <= 18 && offset <= 1023)
                {
                    ui32 f = ((matchlen - 3) << 2) | ((ui32)offset << 6) | 2;
                    fast_write(f, dst, 2);
                    dst += 2;
                }

                else if(matchlen <= 33)
                {
                    ui32 f = ((matchlen - 2) << 2) | ((ui32)offset << 7) | 3;
                    fast_write(f, dst, 3);
                    dst += 3;
                }
                else
                {
                    ui32 f = ((matchlen - 3) << 7) | ((ui32)offset << 15) | 3;
                    fast_write(f, dst, 4);
                    dst += 4;
                }
            }
            else
            {
                *dst = *src;
                src++;
                dst++;
                cword_val = (cword_val >> 1);
            }
#elif QLZ_COMPRESSION_LEVEL == 2

            if(matchlen > 2)
            {
                cword_val = (cword_val >> 1) | (1U << 31);
                src += matchlen;

                if(matchlen < 10)
                {
                    ui32 f = best_k | ((matchlen - 2) << 2) | (hash << 5);
                    fast_write(f, dst, 2);
                    dst += 2;
                }
                else
                {
                    ui32 f = best_k | (matchlen << 16) | (hash << 5);
                    fast_write(f, dst, 3);
                    dst += 3;
                }
            }
            else
            {
                *dst = *src;
                src++;
                dst++;
                cword_val = (cword_val >> 1);
            }
#endif
        }
#endif
    }
    while(src <= last_byte)
    {
        if((cword_val & 1) == 1)
        {
            fast_write((cword_val >> 1) | (1U << 31), cword_ptr, CWORD_LEN);
            cword_ptr = dst;
            dst += CWORD_LEN;
            cword_val = 1U << 31;
        }
#if QLZ_COMPRESSION_LEVEL < 3
        if(src <= last_byte - 3)
        {
#if QLZ_COMPRESSION_LEVEL == 1
            ui32 hash, fetch;
            fetch = fast_read(src, 3);
            hash = hash_func(fetch);
            state->hash[hash].offset = CAST(src - OFFSET_BASE);
            state->hash[hash].cache = fetch;
#elif QLZ_COMPRESSION_LEVEL == 2
            ui32 hash;
            unsigned char c;
            hash = hashat(src);
            c = state->hash_counter[hash];
            state->hash[hash].offset[c & (QLZ_POINTERS - 1)] = src;
            c++;
            state->hash_counter[hash] = c;
#endif
        }
#endif
        *dst = *src;
        src++;
        dst++;
        cword_val = (cword_val >> 1);
    }

    while((cword_val & 1) != 1)
        cword_val = (cword_val >> 1);

    fast_write((cword_val >> 1) | (1U << 31), cword_ptr, CWORD_LEN);

    // min. size must be 9 bytes so that the qlz_size functions can take 9 bytes as argument
    return dst - destination < 9 ? 9 : dst - destination;
}

static size_t qlz_decompress_core(const unsigned char *source, unsigned char *destination, size_t size, qlz_state_decompress *state, const unsigned char *history)
{
    const unsigned char *src = source + qlz_size_header((const char *)source);
    unsigned char *dst = destination;
    const unsigned char *last_destination_byte = destination + size - 1;
    ui32 cword_val = 1;
    const unsigned char *last_matchstart = last_destination_byte - UNCONDITIONAL_MATCHLEN - UNCOMPRESSED_END;
    unsigned char *last_hashed = destination - 1;
    const unsigned char *last_source_byte = source + qlz_size_compressed((const char *)source) - 1;
    static const ui32 bitlut[16] = {4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0};

    (void) last_source_byte;
    (void) last_hashed;
    (void) state;
    (void) history;

    for(;;)
    {
        ui32 fetch;

        if(cword_val == 1)
        {
#ifdef QLZ_MEMORY_SAFE
            if(src + CWORD_LEN - 1 > last_source_byte)
                return 0;
#endif
            cword_val = fast_read(src, CWORD_LEN);
            src += CWORD_LEN;
        }

#ifdef QLZ_MEMORY_SAFE
        if(src + 4 - 1 > last_source_byte)
            return 0;
#endif

        fetch = fast_read(src, 4);

        if((cword_val & 1) == 1)
        {
            ui32 matchlen;
            const unsigned char *offset2;

#if QLZ_COMPRESSION_LEVEL == 1
            ui32 hash;
            cword_val = cword_val >> 1;
            hash = (fetch >> 4) & 0xfff;
            offset2 = (const unsigned char *)(size_t)state->hash[hash].offset;

            if((fetch & 0xf) != 0)
            {
                matchlen = (fetch & 0xf) + 2;
                src += 2;
            }
            else
            {
                matchlen = *(src + 2);
                src += 3;
            }

#elif QLZ_COMPRESSION_LEVEL == 2
            ui32 hash;
            unsigned char c;
            cword_val = cword_val >> 1;
            hash = (fetch >> 5) & 0x7ff;
            c = (unsigned char)(fetch & 0x3);
            offset2 = state->hash[hash].offset[c];

            if((fetch & (28)) != 0)
            {
                matchlen = ((fetch >> 2) & 0x7) + 2;
                src += 2;
            }
            else
            {
                matchlen = *(src + 2);
                src += 3;
            }

#elif QLZ_COMPRESSION_LEVEL == 3
            ui32 offset;
            cword_val = cword_val >> 1;
            if((fetch & 3) == 0)
            {
                offset = (fetch & 0xff) >> 2;
                matchlen = 3;
                src++;
            }
            else if((fetch & 2) == 0)
            {
                offset = (fetch & 0xffff) >> 2;
                matchlen = 3;
                src += 2;
            }
            else if((fetch & 1) == 0)
            {
                offset = (fetch & 0xffff) >> 6;
                matchlen = ((fetch >> 2) & 15) + 3;
                src += 2;
            }
            else if((fetch & 127) != 3)
            {
                offset = (fetch >> 7) & 0x1ffff;
                matchlen = ((fetch >> 2) & 0x1f) + 2;
                src += 3;
            }
            else
            {
                offset = (fetch >> 15);
                matchlen = ((fetch >> 7) & 255) + 3;
                src += 4;
            }

            offset2 = dst - offset;
#endif

#ifdef QLZ_MEMORY_SAFE
            if(offset2 < history || offset2 > dst - MINOFFSET - 1)
                return 0;

            if(matchlen > (ui32)(last_destination_byte - dst - UNCOMPRESSED_END + 1))
                return 0;
#endif

            memcpy_up(dst, offset2, matchlen);
            dst += matchlen;

#if QLZ_COMPRESSION_LEVEL <= 2
            update_hash_upto(state, &last_hashed, dst - matchlen);
            last_hashed = dst - 1;
#endif
        }
        else
        {
            if(dst < last_matchstart)
            {
                unsigned int n = bitlut[cword_val & 0xf];
#ifdef X86X64
                *(ui32 *)dst = *(ui32 *)src;
#else
                memcpy_up(dst, src, 4);
#endif
                cword_val = cword_val >> n;
                dst += n;
                src += n;
#if QLZ_COMPRESSION_LEVEL <= 2
                update_hash_upto(state, &last_hashed, dst - 3);
#endif
            }
            else
            {
                while(dst <= last_destination_byte)
                {
                    if(cword_val == 1)
                    {
                        src += CWORD_LEN;
                        cword_val = 1U << 31;
                    }
#ifdef QLZ_MEMORY_SAFE
                    if(src >= last_source_byte + 1)
                        return 0;
#endif
                    *dst = *src;
                    dst++;
                    src++;
                    cword_val = cword_val >> 1;
                }

#if QLZ_COMPRESSION_LEVEL <= 2
                update_hash_upto(state, &last_hashed, last_destination_byte - 3); // todo, use constant
#endif
                return size;
            }

        }
    }
}

size_t qlz_compress(const void *source, char *destination, size_t size, qlz_state_compress *state)
{
    size_t r;
    ui32 compressed;
    size_t base;

    if(size == 0 || size > 0xffffffff - 400)
        return 0;

    if(size < 216)
        base = 3;
    else
        base = 9;

#if QLZ_STREAMING_BUFFER > 0
    if(state->stream_counter + size - 1 >= QLZ_STREAMING_BUFFER)
#endif
    {
        reset_table_compress(state);
        r = base + qlz_compress_core((const unsigned char *)source, (unsigned char *)destination + base, size, state);
#if QLZ_STREAMING_BUFFER > 0
        reset_table_compress(state);
#endif
        if(r == base)
        {
            memcpy(destination + base, source, size);
            r = size + base;
            compressed = 0;
        }
        else
        {
            compressed = 1;
        }
        state->stream_counter = 0;
    }
#if QLZ_STREAMING_BUFFER > 0
    else
    {
        unsigned char *src = state->stream_buffer + state->stream_counter;

        memcpy(src, source, size);
        r = base + qlz_compress_core(src, (unsigned char *)destination + base, size, state);

        if(r == base)
        {
            memcpy(destination + base, src, size);
            r = size + base;
            compressed = 0;
            reset_table_compress(state);
        }
        else
        {
            compressed = 1;
        }
        state->stream_counter += size;
    }
#endif
    if(base == 3)
    {
        *destination = (unsigned char)(0 | compressed);
        *(destination + 1) = (unsigned char)r;
        *(destination + 2) = (unsigned char)size;
    }
    else
    {
        *destination = (unsigned char)(2 | compressed);
        fast_write((ui32)r, destination + 1, 4);
        fast_write((ui32)size, destination + 5, 4);
    }

    *destination |= (QLZ_COMPRESSION_LEVEL << 2);
    *destination |= (1 << 6);
    *destination |= ((QLZ_STREAMING_BUFFER == 0 ? 0 : (QLZ_STREAMING_BUFFER == 100000 ? 1 : (QLZ_STREAMING_BUFFER == 1000000 ? 2 : 3))) << 4);

// 76543210
// 01SSLLHC

    return r;
}

size_t qlz_decompress(const char *source, void *destination, qlz_state_decompress *state)
{
    size_t dsiz = qlz_size_decompressed(source);

#if QLZ_STREAMING_BUFFER > 0
    if(state->stream_counter + qlz_size_decompressed(source) - 1 >= QLZ_STREAMING_BUFFER)
#endif
    {
        if((*source & 1) == 1)
        {
            reset_table_decompress(state);
            dsiz = qlz_decompress_core((const unsigned char *)source, (unsigned char *)destination, dsiz, state, (const unsigned char *)destination);
        }
        else
        {
            memcpy(destination, source + qlz_size_header(source), dsiz);
        }
        state->stream_counter = 0;
        reset_table_decompress(state);
    }
#if QLZ_STREAMING_BUFFER > 0
    else
    {
        unsigned char *dst = state->stream_buffer + state->stream_counter;
        if((*source & 1) == 1)
        {
            dsiz = qlz_decompress_core((const unsigned char *)source, dst, dsiz, state, (const unsigned char *)state->stream_buffer);
        }
        else
        {
            memcpy(dst, source + qlz_size_header(source), dsiz);
            reset_table_decompress(state);
        }
        memcpy(destination, dst, dsiz);
        state->stream_counter += dsiz;
    }
#endif
    return dsiz;
}