libavutil/lzo.c

   1 /*
   2  * LZO 1x decompression
   3  * Copyright (c) 2006 Reimar Doeffinger
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "avutil.h"
  23 #include "common.h"
  24 //! Avoid e.g. MPlayers fast_memcpy, it slows things down here.
  25 #undef memcpy
  26 #include <string.h>
  27 #include "lzo.h"
  28
  29 //! Define if we may write up to 12 bytes beyond the output buffer.
  30 #define OUTBUF_PADDED 1
  31 //! Define if we may read up to 8 bytes beyond the input buffer.
  32 #define INBUF_PADDED 1
  33 typedef struct LZOContext {
  34     const uint8_t *in, *in_end;
  35     uint8_t *out_start, *out, *out_end;
  36     int error;
  37 } LZOContext;
  38
  39 /**
  40  * \brief Reads one byte from the input buffer, avoiding an overrun.
  41  * \return byte read
  42  */
  43 static inline int get_byte(LZOContext *c) {
  44     if (c->in < c->in_end)
  45         return *c->in++;
  46     c->error |= AV_LZO_INPUT_DEPLETED;
  47     return 1;
  48 }
  49
  50 #ifdef INBUF_PADDED
  51 #define GETB(c) (*(c).in++)
  52 #else
  53 #define GETB(c) get_byte(&(c))
  54 #endif
  55
  56 /**
  57  * \brief Decodes a length value in the coding used by lzo.
  58  * \param x previous byte value
  59  * \param mask bits used from x
  60  * \return decoded length value
  61  */
  62 static inline int get_len(LZOContext *c, int x, int mask) {
  63     int cnt = x & mask;
  64     if (!cnt) {
  65         while (!(x = get_byte(c))) cnt += 255;
  66         cnt += mask + x;
  67     }
  68     return cnt;
  69 }
  70
  71 //#define UNALIGNED_LOADSTORE
  72 #define BUILTIN_MEMCPY
  73 #ifdef UNALIGNED_LOADSTORE
  74 #define COPY2(d, s) *(uint16_t *)(d) = *(uint16_t *)(s);
  75 #define COPY4(d, s) *(uint32_t *)(d) = *(uint32_t *)(s);
  76 #elif defined(BUILTIN_MEMCPY)
  77 #define COPY2(d, s) memcpy(d, s, 2);
  78 #define COPY4(d, s) memcpy(d, s, 4);
  79 #else
  80 #define COPY2(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1];
  81 #define COPY4(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1]; (d)[2] = (s)[2]; (d)[3] = (s)[3];
  82 #endif
  83
  84 /**
  85  * \brief Copies bytes from input to output buffer with checking.
  86  * \param cnt number of bytes to copy, must be >= 0
  87  */
  88 static inline void copy(LZOContext *c, int cnt) {
  89     register const uint8_t *src = c->in;
  90     register uint8_t *dst = c->out;
  91     if (cnt > c->in_end - src) {
  92         cnt = FFMAX(c->in_end - src, 0);
  93         c->error |= AV_LZO_INPUT_DEPLETED;
  94     }
  95     if (cnt > c->out_end - dst) {
  96         cnt = FFMAX(c->out_end - dst, 0);
  97         c->error |= AV_LZO_OUTPUT_FULL;
  98     }
  99 #if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
 100     COPY4(dst, src);
 101     src += 4;
 102     dst += 4;
 103     cnt -= 4;
 104     if (cnt > 0)
 105 #endif
 106         memcpy(dst, src, cnt);
 107     c->in = src + cnt;
 108     c->out = dst + cnt;
 109 }
 110
 111 static inline void memcpy_backptr(uint8_t *dst, int back, int cnt);
 112
 113 /**
 114  * \brief Copies previously decoded bytes to current position.
 115  * \param back how many bytes back we start
 116  * \param cnt number of bytes to copy, must be >= 0
 117  *
 118  * cnt > back is valid, this will copy the bytes we just copied,
 119  * thus creating a repeating pattern with a period length of back.
 120  */
 121 static inline void copy_backptr(LZOContext *c, int back, int cnt) {
 122     register const uint8_t *src = &c->out[-back];
 123     register uint8_t *dst = c->out;
 124     if (src < c->out_start || src > dst) {
 125         c->error |= AV_LZO_INVALID_BACKPTR;
 126         return;
 127     }
 128     if (cnt > c->out_end - dst) {
 129         cnt = FFMAX(c->out_end - dst, 0);
 130         c->error |= AV_LZO_OUTPUT_FULL;
 131     }
 132     memcpy_backptr(dst, back, cnt);
 133     c->out = dst + cnt;
 134 }
 135
 136 static inline void memcpy_backptr(uint8_t *dst, int back, int cnt) {
 137     const uint8_t *src = &dst[-back];
 138     if (back == 1) {
 139         memset(dst, *src, cnt);
 140     } else {
 141 #ifdef OUTBUF_PADDED
 142         COPY2(dst, src);
 143         COPY2(dst + 2, src + 2);
 144         src += 4;
 145         dst += 4;
 146         cnt -= 4;
 147         if (cnt > 0) {
 148             COPY2(dst, src);
 149             COPY2(dst + 2, src + 2);
 150             COPY2(dst + 4, src + 4);
 151             COPY2(dst + 6, src + 6);
 152             src += 8;
 153             dst += 8;
 154             cnt -= 8;
 155         }
 156 #endif
 157         if (cnt > 0) {
 158             int blocklen = back;
 159             while (cnt > blocklen) {
 160                 memcpy(dst, src, blocklen);
 161                 dst += blocklen;
 162                 cnt -= blocklen;
 163                 blocklen <<= 1;
 164             }
 165             memcpy(dst, src, cnt);
 166         }
 167     }
 168 }
 169
 170 void av_memcpy_backptr(uint8_t *dst, int back, int cnt) {
 171     memcpy_backptr(dst, back, cnt);
 172 }
 173
 174 int av_lzo1x_decode(void *out, int *outlen, const void *in, int *inlen) {
 175     int state= 0;
 176     int x;
 177     LZOContext c;
 178     c.in = in;
 179     c.in_end = (const uint8_t *)in + *inlen;
 180     c.out = c.out_start = out;
 181     c.out_end = (uint8_t *)out + * outlen;
 182     c.error = 0;
 183     x = GETB(c);
 184     if (x > 17) {
 185         copy(&c, x - 17);
 186         x = GETB(c);
 187         if (x < 16) c.error |= AV_LZO_ERROR;
 188     }
 189     if (c.in > c.in_end)
 190         c.error |= AV_LZO_INPUT_DEPLETED;
 191     while (!c.error) {
 192         int cnt, back;
 193         if (x > 15) {
 194             if (x > 63) {
 195                 cnt = (x >> 5) - 1;
 196                 back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;
 197             } else if (x > 31) {
 198                 cnt = get_len(&c, x, 31);
 199                 x = GETB(c);
 200                 back = (GETB(c) << 6) + (x >> 2) + 1;
 201             } else {
 202                 cnt = get_len(&c, x, 7);
 203                 back = (1 << 14) + ((x & 8) << 11);
 204                 x = GETB(c);
 205                 back += (GETB(c) << 6) + (x >> 2);
 206                 if (back == (1 << 14)) {
 207                     if (cnt != 1)
 208                         c.error |= AV_LZO_ERROR;
 209                     break;
 210                 }
 211             }
 212         } else if(!state){
 213                 cnt = get_len(&c, x, 15);
 214                 copy(&c, cnt + 3);
 215                 x = GETB(c);
 216                 if (x > 15)
 217                     continue;
 218                 cnt = 1;
 219                 back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;
 220         } else {
 221                 cnt = 0;
 222                 back = (GETB(c) << 2) + (x >> 2) + 1;
 223         }
 224         copy_backptr(&c, back, cnt + 2);
 225         state=
 226         cnt = x & 3;
 227         copy(&c, cnt);
 228         x = GETB(c);
 229     }
 230     *inlen = c.in_end - c.in;
 231     if (c.in > c.in_end)
 232         *inlen = 0;
 233     *outlen = c.out_end - c.out;
 234     return c.error;
 235 }
 236
 237 #ifdef TEST
 238 #include <stdio.h>
 239 #include <lzo/lzo1x.h>
 240 #include "log.h"
 241 #define MAXSZ (10*1024*1024)
 242
 243 /* Define one of these to 1 if you wish to benchmark liblzo
 244  * instead of our native implementation. */
 245 #define BENCHMARK_LIBLZO_SAFE   0
 246 #define BENCHMARK_LIBLZO_UNSAFE 0
 247
 248 int main(int argc, char *argv[]) {
 249     FILE *in = fopen(argv[1], "rb");
 250     uint8_t *orig = av_malloc(MAXSZ + 16);
 251     uint8_t *comp = av_malloc(2*MAXSZ + 16);
 252     uint8_t *decomp = av_malloc(MAXSZ + 16);
 253     size_t s = fread(orig, 1, MAXSZ, in);
 254     lzo_uint clen = 0;
 255     long tmp[LZO1X_MEM_COMPRESS];
 256     int inlen, outlen;
 257     int i;
 258     av_log_set_level(AV_LOG_DEBUG);
 259     lzo1x_999_compress(orig, s, comp, &clen, tmp);
 260     for (i = 0; i < 300; i++) {
 261 START_TIMER
 262         inlen = clen; outlen = MAXSZ;
 263 #if BENCHMARK_LIBLZO_SAFE
 264         if (lzo1x_decompress_safe(comp, inlen, decomp, &outlen, NULL))
 265 #elif BENCHMARK_LIBLZO_UNSAFE
 266         if (lzo1x_decompress(comp, inlen, decomp, &outlen, NULL))
 267 #else
 268         if (av_lzo1x_decode(decomp, &outlen, comp, &inlen))
 269 #endif
 270             av_log(NULL, AV_LOG_ERROR, "decompression error\n");
 271 STOP_TIMER("lzod")
 272     }
 273     if (memcmp(orig, decomp, s))
 274         av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");
 275     else
 276         av_log(NULL, AV_LOG_ERROR, "decompression OK\n");
 277     return 0;
 278 }
 279 #endif