apps/codecs/lib/ffmpeg_bitstream.c

   1 /*
   2  * Common bit i/o utils
   3  * Copyright (c) 2000, 2001 Fabrice Bellard
   4  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
   5  * Copyright (c) 2010 Loren Merritt
   6  *
   7  * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
   8  *
   9  * This file is part of FFmpeg.
  10  *
  11  * FFmpeg is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  15  *
  16  * FFmpeg is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with FFmpeg; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 /**
  27  * @file
  28  * bitstream api.
  29  */
  30
  31 //#include "avcodec.h"
  32 #include "ffmpeg_get_bits.h"
  33 #include "ffmpeg_put_bits.h"
  34 #include "ffmpeg_intreadwrite.h"
  35
  36 #define av_log(...)
  37
  38 #ifdef ROCKBOX
  39 #undef DEBUGF
  40 #define DEBUGF(...)
  41 #endif
  42
  43 const uint8_t ff_log2_run[32]={
  44  0, 0, 0, 0, 1, 1, 1, 1,
  45  2, 2, 2, 2, 3, 3, 3, 3,
  46  4, 4, 5, 5, 6, 6, 7, 7,
  47  8, 9,10,11,12,13,14,15
  48 };
  49
  50 #if 0 // unused in rockbox
  51 void align_put_bits(PutBitContext *s)
  52 {
  53 #ifdef ALT_BITSTREAM_WRITER
  54     put_bits(s,(  - s->index) & 7,0);
  55 #else
  56     put_bits(s,s->bit_left & 7,0);
  57 #endif
  58 }
  59
  60 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
  61 {
  62     while(*string){
  63         put_bits(pb, 8, *string);
  64         string++;
  65     }
  66     if(terminate_string)
  67         put_bits(pb, 8, 0);
  68 }
  69 #endif
  70
  71 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
  72 {
  73     int words= length>>4;
  74     int bits= length&15;
  75     int i;
  76
  77     if(length==0) return;
  78
  79     if(words < 16 || put_bits_count(pb)&7){
  80         for(i=0; i<words; i++) put_bits(pb, 16, AV_RB16(src + 2*i));
  81     }else{
  82         for(i=0; put_bits_count(pb)&31; i++)
  83             put_bits(pb, 8, src[i]);
  84         flush_put_bits(pb);
  85         memcpy(put_bits_ptr(pb), src+i, 2*words-i);
  86         skip_put_bytes(pb, 2*words-i);
  87     }
  88
  89     put_bits(pb, bits, AV_RB16(src + 2*words)>>(16-bits));
  90 }
  91
  92 /* VLC decoding */
  93
  94 //#define DEBUG_VLC
  95
  96 #define GET_DATA(v, table, i, wrap, size) \
  97 {\
  98     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
  99     switch(size) {\
 100     case 1:\
 101         v = *(const uint8_t *)ptr;\
 102         break;\
 103     case 2:\
 104         v = *(const uint16_t *)ptr;\
 105         break;\
 106     default:\
 107         v = *(const uint32_t *)ptr;\
 108         break;\
 109     }\
 110 }
 111
 112
 113 static int alloc_table(VLC *vlc, int size, int use_static)
 114 {
 115     int index;
 116     index = vlc->table_size;
 117     vlc->table_size += size;
 118     if (vlc->table_size > vlc->table_allocated) {
 119         if(use_static)
 120         {
 121             DEBUGF("init_vlc() used with too little memory : table_size > allocated_memory\n");
 122             return -1;
 123         }
 124 //            abort(); //cant do anything, init_vlc() is used with too little memory
 125 //        vlc->table_allocated += (1 << vlc->bits);
 126 //        vlc->table = av_realloc(vlc->table,
 127 //                                sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
 128         if (!vlc->table)
 129             return -1;
 130     }
 131     return index;
 132 }
 133
 134 /*
 135 static av_always_inline uint32_t bitswap_32(uint32_t x) {
 136     return av_reverse[x&0xFF]<<24
 137          | av_reverse[(x>>8)&0xFF]<<16
 138          | av_reverse[(x>>16)&0xFF]<<8
 139          | av_reverse[x>>24];
 140 }
 141 */
 142
 143 typedef struct {
 144     uint8_t bits;
 145     uint16_t symbol;
 146     /** codeword, with the first bit-to-be-read in the msb
 147      * (even if intended for a little-endian bitstream reader) */
 148     uint32_t code;
 149 } __attribute__((__packed__)) VLCcode; /* packed to save space */
 150
 151 static int compare_vlcspec(const void *a, const void *b)
 152 {
 153     const VLCcode *sa=a, *sb=b;
 154     return (sa->code >> 1) - (sb->code >> 1);
 155 }
 156
 157 /**
 158  * Build VLC decoding tables suitable for use with get_vlc().
 159  *
 160  * @param vlc            the context to be initted
 161  *
 162  * @param table_nb_bits  max length of vlc codes to store directly in this table
 163  *                       (Longer codes are delegated to subtables.)
 164  *
 165  * @param nb_codes       number of elements in codes[]
 166  *
 167  * @param codes          descriptions of the vlc codes
 168  *                       These must be ordered such that codes going into the same subtable are contiguous.
 169  *                       Sorting by VLCcode.code is sufficient, though not necessary.
 170  */
 171 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
 172                        VLCcode *codes, int flags)
 173 {
 174     int table_size, table_index, index, symbol, subtable_bits;
 175     int i, j, k, n, nb, inc;
 176     uint32_t code, code_prefix;
 177     VLC_TYPE (*table)[2];
 178
 179     table_size = 1 << table_nb_bits;
 180     table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
 181 #ifdef DEBUG_VLC
 182     av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d\n",
 183            table_index, table_size);
 184 #endif
 185     if (table_index < 0)
 186         return -1;
 187     table = &vlc->table[table_index];
 188
 189     for (i = 0; i < table_size; i++) {
 190         table[i][1] = 0; //bits
 191         table[i][0] = -1; //codes
 192     }
 193
 194     /* first pass: map codes and compute auxillary table sizes */
 195     for (i = 0; i < nb_codes; i++) {
 196         n = codes[i].bits;
 197         code = codes[i].code;
 198         symbol = codes[i].symbol;
 199 #if defined(DEBUG_VLC) && 0
 200         av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code);
 201 #endif
 202         if (n <= table_nb_bits) {
 203             /* no need to add another table */
 204             j = code >> (32 - table_nb_bits);
 205             nb = 1 << (table_nb_bits - n);
 206             inc = 1;
 207 /*            if (flags & INIT_VLC_LE) {
 208                 j = bitswap_32(code);
 209                 inc = 1 << n;
 210             } */
 211             for (k = 0; k < nb; k++) {
 212 #ifdef DEBUG_VLC
 213                 av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
 214                        j, i, n);
 215 #endif
 216                 if (table[j][1] /*bits*/ != 0) {
 217                     av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
 218                     return -1;
 219                 }
 220                 table[j][1] = n; //bits
 221                 table[j][0] = symbol;
 222                 j += inc;
 223             }
 224         } else {
 225             /* fill auxiliary table recursively */
 226             n -= table_nb_bits;
 227             code_prefix = code >> (32 - table_nb_bits);
 228             subtable_bits = n;
 229             codes[i].bits = n;
 230             codes[i].code = code << table_nb_bits;
 231             for (k = i+1; k < nb_codes; k++) {
 232                 n = codes[k].bits - table_nb_bits;
 233                 if (n <= 0)
 234                     break;
 235                 code = codes[k].code;
 236                 if (code >> (32 - table_nb_bits) != code_prefix)
 237                     break;
 238                 codes[k].bits = n;
 239                 codes[k].code = code << table_nb_bits;
 240                 subtable_bits = FFMAX(subtable_bits, n);
 241             }
 242             subtable_bits = FFMIN(subtable_bits, table_nb_bits);
 243             j = /*(flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) :*/ code_prefix;
 244             table[j][1] = -subtable_bits;
 245 #ifdef DEBUG_VLC
 246             av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)\n",
 247                    j, codes[i].bits + table_nb_bits);
 248 #endif
 249             index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
 250             if (index < 0)
 251                 return -1;
 252             /* note: realloc has been done, so reload tables */
 253             table = &vlc->table[table_index];
 254             table[j][0] = index; //code
 255             i = k-1;
 256         }
 257     }
 258     return table_index;
 259 }
 260
 261
 262 /* Build VLC decoding tables suitable for use with get_vlc().
 263
 264    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 265    bigger it is, the faster is the decoding. But it should not be too
 266    big to save memory and L1 cache. '9' is a good compromise.
 267
 268    'nb_codes' : number of vlcs codes
 269
 270    'bits' : table which gives the size (in bits) of each vlc code.
 271
 272    'codes' : table which gives the bit pattern of of each vlc code.
 273
 274    'symbols' : table which gives the values to be returned from get_vlc().
 275
 276    'xxx_wrap' : give the number of bytes between each entry of the
 277    'bits' or 'codes' tables.
 278
 279    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 280    or 'codes' tables.
 281
 282    'wrap' and 'size' allows to use any memory configuration and types
 283    (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
 284
 285    'use_static' should be set to 1 for tables, which should be freed
 286    with av_free_static(), 0 if free_vlc() will be used.
 287 */
 288
 289 /* Rockbox: support for INIT_VLC_LE is currently disabled since none of our
 290    codecs use it, there's a LUT based bit reverse function for this commented
 291    out above (bitswap_32) and an inline asm version in libtremor/codebook.c
 292    if we ever want this */
 293
 294 static VLCcode buf[1336+1]; /* worst case is wma, which has one table with 1336 entries */
 295
 296 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 297              const void *bits, int bits_wrap, int bits_size,
 298              const void *codes, int codes_wrap, int codes_size,
 299              const void *symbols, int symbols_wrap, int symbols_size,
 300              int flags)
 301 {
 302     if (nb_codes+1 > (int)(sizeof (buf)/ sizeof (VLCcode)))
 303     {
 304         DEBUGF("Table is larger than temp buffer!\n");
 305         return -1;
 306     }
 307
 308     int i, j, ret;
 309
 310     vlc->bits = nb_bits;
 311     if(flags & INIT_VLC_USE_NEW_STATIC){
 312         if(vlc->table_size && vlc->table_size == vlc->table_allocated){
 313             return 0;
 314         }else if(vlc->table_size){
 315             DEBUGF("fatal error, we are called on a partially initialized table\n");
 316             return -1;
 317 //            abort(); // fatal error, we are called on a partially initialized table
 318         }
 319     }else {
 320         vlc->table = NULL;
 321         vlc->table_allocated = 0;
 322         vlc->table_size = 0;
 323     }
 324
 325 #ifdef DEBUG_VLC
 326     av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes);
 327 #endif
 328
 329 //    buf = av_malloc((nb_codes+1)*sizeof(VLCcode));
 330
 331 //    assert(symbols_size <= 2 || !symbols);
 332     j = 0;
 333 #define COPY(condition)\
 334     for (i = 0; i < nb_codes; i++) {\
 335         GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size);\
 336         if (!(condition))\
 337             continue;\
 338         GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);\
 339 /*        if (flags & INIT_VLC_LE)*/\
 340 /*            buf[j].code = bitswap_32(buf[j].code);*/\
 341 /*        else*/\
 342             buf[j].code <<= 32 - buf[j].bits;\
 343         if (symbols)\
 344             GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size)\
 345         else\
 346             buf[j].symbol = i;\
 347         j++;\
 348     }
 349     COPY(buf[j].bits > nb_bits);
 350     // qsort is the slowest part of init_vlc, and could probably be improved or avoided
 351     qsort(buf, j, sizeof(VLCcode), compare_vlcspec);
 352     COPY(buf[j].bits && buf[j].bits <= nb_bits);
 353     nb_codes = j;
 354
 355     ret = build_table(vlc, nb_bits, nb_codes, buf, flags);
 356
 357 //    av_free(buf);
 358     if (ret < 0) {
 359 //        av_freep(&vlc->table);
 360         return -1;
 361     }
 362     if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated) {
 363         av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
 364     }
 365     return 0;
 366 }
 367
 368 /* not used in rockbox
 369 void free_vlc(VLC *vlc)
 370 {
 371     av_freep(&vlc->table);
 372 }
 373 */
 374