PeerStreamer

/*

 * LZO 1x decompression

 * Copyright (c) 2006 Reimar Doeffinger

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "common.h"

//! avoid e.g. MPlayers fast_memcpy, it slows things down here

#undef memcpy

#include <string.h>

#include "lzo.h"

//! define if we may write up to 12 bytes beyond the output buffer

#define OUTBUF_PADDED 1

//! define if we may read up to 8 bytes beyond the input buffer

#define INBUF_PADDED 1

typedef struct LZOContext {

    const uint8_t *in, *in_end;

    uint8_t *out_start, *out, *out_end;

    int error;

} LZOContext;

/**

 * \brief read one byte from input buffer, avoiding overrun

 * \return byte read

 */

static inline int get_byte(LZOContext *c) {

    if (c->in < c->in_end)

        return *c->in++;

    c->error |= LZO_INPUT_DEPLETED;

    return 1;

}

#ifdef INBUF_PADDED

#define GETB(c) (*(c).in++)

#else

#define GETB(c) get_byte(&(c))

#endif

/**

 * \brief decode a length value in the coding used by lzo

 * \param x previous byte value

 * \param mask bits used from x

 * \return decoded length value

 */

static inline int get_len(LZOContext *c, int x, int mask) {

    int cnt = x & mask;

    if (!cnt) {

        while (!(x = get_byte(c))) cnt += 255;

        cnt += mask + x;

    }

    return cnt;

}

//#define UNALIGNED_LOADSTORE

#define BUILTIN_MEMCPY

#ifdef UNALIGNED_LOADSTORE

#define COPY2(d, s) *(uint16_t *)(d) = *(uint16_t *)(s);

#define COPY4(d, s) *(uint32_t *)(d) = *(uint32_t *)(s);

#elif defined(BUILTIN_MEMCPY)

#define COPY2(d, s) memcpy(d, s, 2);

#define COPY4(d, s) memcpy(d, s, 4);

#else

#define COPY2(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1];

#define COPY4(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1]; (d)[2] = (s)[2]; (d)[3] = (s)[3];

#endif

/**

 * \brief copy bytes from input to output buffer with checking

 * \param cnt number of bytes to copy, must be >= 0

 */

static inline void copy(LZOContext *c, int cnt) {

    register const uint8_t *src = c->in;

    register uint8_t *dst = c->out;

    if (cnt > c->in_end - src) {

        cnt = FFMAX(c->in_end - src, 0);

        c->error |= LZO_INPUT_DEPLETED;

    }

    if (cnt > c->out_end - dst) {

        cnt = FFMAX(c->out_end - dst, 0);

        c->error |= LZO_OUTPUT_FULL;

    }

#if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)

    COPY4(dst, src);

    src += 4;

    dst += 4;

    cnt -= 4;

    if (cnt > 0)

#endif

        memcpy(dst, src, cnt);

    c->in = src + cnt;

    c->out = dst + cnt;

}

static inline void memcpy_backptr(uint8_t *dst, int back, int cnt);

/**

 * \brief copy previously decoded bytes to current position

 * \param back how many bytes back we start

 * \param cnt number of bytes to copy, must be >= 0

 *

 * cnt > back is valid, this will copy the bytes we just copied,

 * thus creating a repeating pattern with a period length of back.

 */

static inline void copy_backptr(LZOContext *c, int back, int cnt) {

    register const uint8_t *src = &c->out[-back];

    register uint8_t *dst = c->out;

    if (src < c->out_start || src > dst) {

        c->error |= LZO_INVALID_BACKPTR;

        return;

    }

    if (cnt > c->out_end - dst) {

        cnt = FFMAX(c->out_end - dst, 0);

        c->error |= LZO_OUTPUT_FULL;

    }

    memcpy_backptr(dst, back, cnt);

    c->out = dst + cnt;

}

static inline void memcpy_backptr(uint8_t *dst, int back, int cnt) {

    const uint8_t *src = &dst[-back];

    if (back == 1) {

        memset(dst, *src, cnt);

    } else {

#ifdef OUTBUF_PADDED

        COPY2(dst, src);

        COPY2(dst + 2, src + 2);

        src += 4;

        dst += 4;

        cnt -= 4;

        if (cnt > 0) {

            COPY2(dst, src);

            COPY2(dst + 2, src + 2);

            COPY2(dst + 4, src + 4);

            COPY2(dst + 6, src + 6);

            src += 8;

            dst += 8;

            cnt -= 8;

        }

#endif

        if (cnt > 0) {

            int blocklen = back;

            while (cnt > blocklen) {

                memcpy(dst, src, blocklen);

                dst += blocklen;

                cnt -= blocklen;

                blocklen <<= 1;

            }

            memcpy(dst, src, cnt);

        }

    }

}

/**

 * \brief deliberately overlapping memcpy implementation

 * \param dst destination buffer; must be padded with 12 additional bytes

 * \param back how many bytes back we start (the initial size of the overlapping window)

 * \param cnt number of bytes to copy, must be >= 0

 *

 * cnt > back is valid, this will copy the bytes we just copied,

 * thus creating a repeating pattern with a period length of back.

 */

void av_memcpy_backptr(uint8_t *dst, int back, int cnt) {

    memcpy_backptr(dst, back, cnt);

}

/**

 * \brief decode LZO 1x compressed data

 * \param out output buffer

 * \param outlen size of output buffer, number of bytes left are returned here

 * \param in input buffer

 * \param inlen size of input buffer, number of bytes left are returned here

 * \return 0 on success, otherwise error flags, see lzo.h

 *

 * make sure all buffers are appropriately padded, in must provide

 * LZO_INPUT_PADDING, out must provide LZO_OUTPUT_PADDING additional bytes

 */

int lzo1x_decode(void *out, int *outlen, const void *in, int *inlen) {

    int state= 0;

    int x;

    LZOContext c;

    c.in = in;

    c.in_end = (const uint8_t *)in + *inlen;

    c.out = c.out_start = out;

    c.out_end = (uint8_t *)out + * outlen;

    c.error = 0;

    x = GETB(c);

    if (x > 17) {

        copy(&c, x - 17);

        x = GETB(c);

        if (x < 16) c.error |= LZO_ERROR;

    }

    if (c.in > c.in_end)

        c.error |= LZO_INPUT_DEPLETED;

    while (!c.error) {

        int cnt, back;

        if (x > 15) {

            if (x > 63) {

                cnt = (x >> 5) - 1;

                back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;

            } else if (x > 31) {

                cnt = get_len(&c, x, 31);

                x = GETB(c);

                back = (GETB(c) << 6) + (x >> 2) + 1;

            } else {

                cnt = get_len(&c, x, 7);

                back = (1 << 14) + ((x & 8) << 11);

                x = GETB(c);

                back += (GETB(c) << 6) + (x >> 2);

                if (back == (1 << 14)) {

                    if (cnt != 1)

                        c.error |= LZO_ERROR;

                    break;

                }

            }

        } else if(!state){

                cnt = get_len(&c, x, 15);

                copy(&c, cnt + 3);

                x = GETB(c);

                if (x > 15)

                    continue;

                cnt = 1;

                back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;

        } else {

                cnt = 0;

                back = (GETB(c) << 2) + (x >> 2) + 1;

        }

        copy_backptr(&c, back, cnt + 2);

        state=

        cnt = x & 3;

        copy(&c, cnt);

        x = GETB(c);

    }

    *inlen = c.in_end - c.in;

    if (c.in > c.in_end)

        *inlen = 0;

    *outlen = c.out_end - c.out;

    return c.error;

}

#ifdef TEST

#include <stdio.h>

#include <lzo/lzo1x.h>

#include "log.h"

#define MAXSZ (10*1024*1024)

int main(int argc, char *argv[]) {

    FILE *in = fopen(argv[1], "rb");

    uint8_t *orig = av_malloc(MAXSZ + 16);

    uint8_t *comp = av_malloc(2*MAXSZ + 16);

    uint8_t *decomp = av_malloc(MAXSZ + 16);

    size_t s = fread(orig, 1, MAXSZ, in);

    lzo_uint clen = 0;

    long tmp[LZO1X_MEM_COMPRESS];

    int inlen, outlen;

    int i;

    av_log_level = AV_LOG_DEBUG;

    lzo1x_999_compress(orig, s, comp, &clen, tmp);

    for (i = 0; i < 300; i++) {

START_TIMER

        inlen = clen; outlen = MAXSZ;

#ifdef LIBLZO

        if (lzo1x_decompress_safe(comp, inlen, decomp, &outlen, NULL))

#elif defined(LIBLZO_UNSAFE)

        if (lzo1x_decompress(comp, inlen, decomp, &outlen, NULL))

#else

        if (lzo1x_decode(decomp, &outlen, comp, &inlen))

#endif

            av_log(NULL, AV_LOG_ERROR, "decompression error\n");

STOP_TIMER("lzod")

    }

    if (memcmp(orig, decomp, s))

        av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");

    else

        av_log(NULL, AV_LOG_ERROR, "decompression ok\n");

    return 0;

}

#endif