diff options
Diffstat (limited to 'media/ffvpx/libavutil/lzo.c')
| -rw-r--r-- | media/ffvpx/libavutil/lzo.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/media/ffvpx/libavutil/lzo.c b/media/ffvpx/libavutil/lzo.c new file mode 100644 index 000000000..1ae076e33 --- /dev/null +++ b/media/ffvpx/libavutil/lzo.c @@ -0,0 +1,205 @@ +/* + * 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 <string.h> + +#include "avutil.h" +#include "avassert.h" +#include "common.h" +#include "intreadwrite.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 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))) { + if (cnt >= INT_MAX - 1000) { + 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; + av_assert0(cnt >= 0); + 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; + av_assert0(cnt > 0); + 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) { + 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 |= AV_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; +} |