/*

* 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 <stdint.h>

#include <string.h>

//#include "avassert.h"

//#include "intreadwrite.h"

//#include "macros.h"

//#include "mem.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 Reads one byte from the input buffer, avoiding an overrun.

* @return byte read

*/

static inline int get_byte(LZOContext *c)

{

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

return *c->in++;

c->error |= AV_LZO_INPUT_DEPLETED;

return 1;

}

#ifdef INBUF_PADDED

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

#else

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

#endif

/**

* @brief Decodes 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))) {

c->error |= AV_LZO_ERROR;

break;

}

cnt += 255;

}

cnt += mask + x;

}

return cnt;

}

/**

* @brief Copies 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 |= AV_LZO_INPUT_DEPLETED;

}

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

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

c->error |= AV_LZO_OUTPUT_FULL;

}

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

AV_COPY32U(dst, src);

src += 4;

dst += 4;

cnt -= 4;

if (cnt > 0)

#endif

memcpy(dst, src, cnt);

c->in = src + cnt;

c->out = dst + cnt;

}

/**

* @brief Copies previously decoded bytes to current position.

* @param back how many bytes back we start, must be > 0

* @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 uint8_t *dst = c->out;

if (dst - c->out_start < back) {

c->error |= AV_LZO_INVALID_BACKPTR;

return;

}

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

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

c->error |= AV_LZO_OUTPUT_FULL;

}

av_memcpy_backptr(dst, back, cnt);

c->out = dst + cnt;

}

int av_lzo1x_decode(void *out, int *outlen, const void *in, int *inlen)

{

int state = 0;

int x;

LZOContext c;

if (*outlen <= 0 || *inlen <= 0) {

int res = 0;

if (*outlen <= 0)

res |= AV_LZO_OUTPUT_FULL;

if (*inlen <= 0)

res |= AV_LZO_INPUT_DEPLETED;

return res;

}

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 |= AV_LZO_ERROR;

}

if (c.in > c.in_end)

c.error |= AV_LZO_INPUT_DEPLETED;

while (!c.error) {

int cnt, back;

if (x > 15) {

cnt = (x >> 5) - 1;

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

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

x = GETB(c);

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

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 |= AV_LZO_ERROR;

break;

}

}

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;

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;

}