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 #include "common.h"
  22 //! avoid e.g. MPlayers fast_memcpy, it slows things down here
  23 #undef memcpy
  24 #include <string.h>
  25 #include "lzo.h"
  26
  27 //! define if we may write up to 12 bytes beyond the output buffer
  28 #define OUTBUF_PADDED 1
  29 //! define if we may read up to 8 bytes beyond the input buffer
  30 #define INBUF_PADDED 1
  31 typedef struct LZOContext {
  32     const uint8_t *in, *in_end;
  33     uint8_t *out_start, *out, *out_end;
  34     int error;
  35 } LZOContext;
  36
  37 /**
  38  * \brief read one byte from input buffer, avoiding overrun
  39  * \return byte read
  40  */
  41 static inline int get_byte(LZOContext *c) {
  42     if (c->in < c->in_end)
  43         return *c->in++;
  44     c->error |= LZO_INPUT_DEPLETED;
  45     return 1;
  46 }
  47
  48 #ifdef INBUF_PADDED
  49 #define GETB(c) (*(c).in++)
  50 #else
  51 #define GETB(c) get_byte(&(c))
  52 #endif
  53
  54 /**
  55  * \brief decode a length value in the coding used by lzo
  56  * \param x previous byte value
  57  * \param mask bits used from x
  58  * \return decoded length value
  59  */
  60 static inline int get_len(LZOContext *c, int x, int mask) {
  61     int cnt = x & mask;
  62     if (!cnt) {
  63         while (!(x = get_byte(c))) cnt += 255;
  64         cnt += mask + x;
  65     }
  66     return cnt;
  67 }
  68
  69 //#define UNALIGNED_LOADSTORE
  70 #define BUILTIN_MEMCPY
  71 #ifdef UNALIGNED_LOADSTORE
  72 #define COPY2(d, s) *(uint16_t *)(d) = *(uint16_t *)(s);
  73 #define COPY4(d, s) *(uint32_t *)(d) = *(uint32_t *)(s);
  74 #elif defined(BUILTIN_MEMCPY)
  75 #define COPY2(d, s) memcpy(d, s, 2);
  76 #define COPY4(d, s) memcpy(d, s, 4);
  77 #else
  78 #define COPY2(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1];
  79 #define COPY4(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1]; (d)[2] = (s)[2]; (d)[3] = (s)[3];
  80 #endif
  81
  82 /**
  83  * \brief copy bytes from input to output buffer with checking
  84  * \param cnt number of bytes to copy, must be >= 0
  85  */
  86 static inline void copy(LZOContext *c, int cnt) {
  87     register const uint8_t *src = c->in;
  88     register uint8_t *dst = c->out;
  89     if (cnt > c->in_end - src) {
  90         cnt = FFMAX(c->in_end - src, 0);
  91         c->error |= LZO_INPUT_DEPLETED;
  92     }
  93     if (cnt > c->out_end - dst) {
  94         cnt = FFMAX(c->out_end - dst, 0);
  95         c->error |= LZO_OUTPUT_FULL;
  96     }
  97 #if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
  98     COPY4(dst, src);
  99     src += 4;
 100     dst += 4;
 101     cnt -= 4;
 102     if (cnt > 0)
 103 #endif
 104         memcpy(dst, src, cnt);
 105     c->in = src + cnt;
 106     c->out = dst + cnt;
 107 }
 108
 109 static inline void memcpy_backptr(uint8_t *dst, int back, int cnt);
 110
 111 /**
 112  * \brief copy previously decoded bytes to current position
 113  * \param back how many bytes back we start
 114  * \param cnt number of bytes to copy, must be >= 0
 115  *
 116  * cnt > back is valid, this will copy the bytes we just copied,
 117  * thus creating a repeating pattern with a period length of back.
 118  */
 119 static inline void copy_backptr(LZOContext *c, int back, int cnt) {
 120     register const uint8_t *src = &c->out[-back];
 121     register uint8_t *dst = c->out;
 122     if (src < c->out_start || src > dst) {
 123         c->error |= LZO_INVALID_BACKPTR;
 124         return;
 125     }
 126     if (cnt > c->out_end - dst) {
 127         cnt = FFMAX(c->out_end - dst, 0);
 128         c->error |= LZO_OUTPUT_FULL;
 129     }
 130     memcpy_backptr(dst, back, cnt);
 131     c->out = dst + cnt;
 132 }
 133
 134 static inline void memcpy_backptr(uint8_t *dst, int back, int cnt) {
 135     const uint8_t *src = &dst[-back];
 136     if (back == 1) {
 137         memset(dst, *src, cnt);
 138     } else {
 139 #ifdef OUTBUF_PADDED
 140         COPY2(dst, src);
 141         COPY2(dst + 2, src + 2);
 142         src += 4;
 143         dst += 4;
 144         cnt -= 4;
 145         if (cnt > 0) {
 146             COPY2(dst, src);
 147             COPY2(dst + 2, src + 2);
 148             COPY2(dst + 4, src + 4);
 149             COPY2(dst + 6, src + 6);
 150             src += 8;
 151             dst += 8;
 152             cnt -= 8;
 153         }
 154 #endif
 155         if (cnt > 0) {
 156             int blocklen = back;
 157             while (cnt > blocklen) {
 158                 memcpy(dst, src, blocklen);
 159                 dst += blocklen;
 160                 cnt -= blocklen;
 161                 blocklen <<= 1;
 162             }
 163             memcpy(dst, src, cnt);
 164         }
 165     }
 166 }
 167
 168 /**
 169  * \brief deliberately overlapping memcpy implementation
 170  * \param dst destination buffer; must be padded with 12 additional bytes
 171  * \param back how many bytes back we start (the initial size of the overlapping window)
 172  * \param cnt number of bytes to copy, must be >= 0
 173  *
 174  * cnt > back is valid, this will copy the bytes we just copied,
 175  * thus creating a repeating pattern with a period length of back.
 176  */
 177 void av_memcpy_backptr(uint8_t *dst, int back, int cnt) {
 178     memcpy_backptr(dst, back, cnt);
 179 }
 180
 181 /**
 182  * \brief decode LZO 1x compressed data
 183  * \param out output buffer
 184  * \param outlen size of output buffer, number of bytes left are returned here
 185  * \param in input buffer
 186  * \param inlen size of input buffer, number of bytes left are returned here
 187  * \return 0 on success, otherwise error flags, see lzo.h
 188  *
 189  * make sure all buffers are appropriately padded, in must provide
 190  * LZO_INPUT_PADDING, out must provide LZO_OUTPUT_PADDING additional bytes
 191  */
 192 int lzo1x_decode(void *out, int *outlen, const void *in, int *inlen) {
 193     int state= 0;
 194     int x;
 195     LZOContext c;
 196     c.in = in;
 197     c.in_end = (const uint8_t *)in + *inlen;
 198     c.out = c.out_start = out;
 199     c.out_end = (uint8_t *)out + * outlen;
 200     c.error = 0;
 201     x = GETB(c);
 202     if (x > 17) {
 203         copy(&c, x - 17);
 204         x = GETB(c);
 205         if (x < 16) c.error |= LZO_ERROR;
 206     }
 207     if (c.in > c.in_end)
 208         c.error |= LZO_INPUT_DEPLETED;
 209     while (!c.error) {
 210         int cnt, back;
 211         if (x > 15) {
 212             if (x > 63) {
 213                 cnt = (x >> 5) - 1;
 214                 back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;
 215             } else if (x > 31) {
 216                 cnt = get_len(&c, x, 31);
 217                 x = GETB(c);
 218                 back = (GETB(c) << 6) + (x >> 2) + 1;
 219             } else {
 220                 cnt = get_len(&c, x, 7);
 221                 back = (1 << 14) + ((x & 8) << 11);
 222                 x = GETB(c);
 223                 back += (GETB(c) << 6) + (x >> 2);
 224                 if (back == (1 << 14)) {
 225                     if (cnt != 1)
 226                         c.error |= LZO_ERROR;
 227                     break;
 228                 }
 229             }
 230         } else if(!state){
 231                 cnt = get_len(&c, x, 15);
 232                 copy(&c, cnt + 3);
 233                 x = GETB(c);
 234                 if (x > 15)
 235                     continue;
 236                 cnt = 1;
 237                 back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;
 238         } else {
 239                 cnt = 0;
 240                 back = (GETB(c) << 2) + (x >> 2) + 1;
 241         }
 242         copy_backptr(&c, back, cnt + 2);
 243         state=
 244         cnt = x & 3;
 245         copy(&c, cnt);
 246         x = GETB(c);
 247     }
 248     *inlen = c.in_end - c.in;
 249     if (c.in > c.in_end)
 250         *inlen = 0;
 251     *outlen = c.out_end - c.out;
 252     return c.error;
 253 }
 254
 255 #ifdef TEST
 256 #include <stdio.h>
 257 #include <lzo/lzo1x.h>
 258 #include "log.h"
 259 #define MAXSZ (10*1024*1024)
 260 int main(int argc, char *argv[]) {
 261     FILE *in = fopen(argv[1], "rb");
 262     uint8_t *orig = av_malloc(MAXSZ + 16);
 263     uint8_t *comp = av_malloc(2*MAXSZ + 16);
 264     uint8_t *decomp = av_malloc(MAXSZ + 16);
 265     size_t s = fread(orig, 1, MAXSZ, in);
 266     lzo_uint clen = 0;
 267     long tmp[LZO1X_MEM_COMPRESS];
 268     int inlen, outlen;
 269     int i;
 270     av_log_level = AV_LOG_DEBUG;
 271     lzo1x_999_compress(orig, s, comp, &clen, tmp);
 272     for (i = 0; i < 300; i++) {
 273 START_TIMER
 274         inlen = clen; outlen = MAXSZ;
 275 #ifdef LIBLZO
 276         if (lzo1x_decompress_safe(comp, inlen, decomp, &outlen, NULL))
 277 #elif defined(LIBLZO_UNSAFE)
 278         if (lzo1x_decompress(comp, inlen, decomp, &outlen, NULL))
 279 #else
 280         if (lzo1x_decode(decomp, &outlen, comp, &inlen))
 281 #endif
 282             av_log(NULL, AV_LOG_ERROR, "decompression error\n");
 283 STOP_TIMER("lzod")
 284     }
 285     if (memcmp(orig, decomp, s))
 286         av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");
 287     else
 288         av_log(NULL, AV_LOG_ERROR, "decompression ok\n");
 289     return 0;
 290 }
 291 #endif