3 * Copyright (c) 2000, 2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5 * Copyright (c) 2010 Loren Merritt
7 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
9 * This file is part of FFmpeg.
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.
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.
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
31 #include "libavutil/avassert.h"
32 #include "libavutil/qsort.h"
39 const uint8_t ff_log2_run[41]={
40 0, 0, 0, 0, 1, 1, 1, 1,
41 2, 2, 2, 2, 3, 3, 3, 3,
42 4, 4, 5, 5, 6, 6, 7, 7,
43 8, 9,10,11,12,13,14,15,
44 16,17,18,19,20,21,22,23,
48 #if FF_API_AVPRIV_PUT_BITS
49 void avpriv_align_put_bits(PutBitContext *s)
53 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
55 ff_copy_bits(pb, src, length);
59 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
62 put_bits(pb, 8, *string);
69 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
71 int words = length >> 4;
72 int bits = length & 15;
78 av_assert0(length <= put_bits_left(pb));
80 if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
81 for (i = 0; i < words; i++)
82 put_bits(pb, 16, AV_RB16(src + 2 * i));
84 for (i = 0; put_bits_count(pb) & 31; i++)
85 put_bits(pb, 8, src[i]);
87 memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
88 skip_put_bytes(pb, 2 * words - i);
91 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
96 #define GET_DATA(v, table, i, wrap, size) \
98 const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
101 v = *(const uint8_t *)ptr; \
104 v = *(const uint16_t *)ptr; \
107 v = *(const uint32_t *)ptr; \
115 static int alloc_table(VLC *vlc, int size, int use_static)
117 int index = vlc->table_size;
119 vlc->table_size += size;
120 if (vlc->table_size > vlc->table_allocated) {
122 abort(); // cannot do anything, init_vlc() is used with too little memory
123 vlc->table_allocated += (1 << vlc->bits);
124 vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
126 vlc->table_allocated = 0;
128 return AVERROR(ENOMEM);
130 memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
135 #define LOCALBUF_ELEMS 1500 // the maximum currently needed is 1296 by rv34
137 typedef struct VLCcode {
140 /** codeword, with the first bit-to-be-read in the msb
141 * (even if intended for a little-endian bitstream reader) */
145 static int vlc_common_init(VLC *vlc_arg, int nb_bits, int nb_codes,
146 VLC **vlc, VLC *localvlc, VLCcode **buf,
150 (*vlc)->bits = nb_bits;
151 if (flags & INIT_VLC_USE_NEW_STATIC) {
152 av_assert0(nb_codes <= LOCALBUF_ELEMS);
153 *localvlc = *vlc_arg;
155 (*vlc)->table_size = 0;
157 (*vlc)->table = NULL;
158 (*vlc)->table_allocated = 0;
159 (*vlc)->table_size = 0;
161 if (nb_codes > LOCALBUF_ELEMS) {
162 *buf = av_malloc_array(nb_codes, sizeof(VLCcode));
164 return AVERROR(ENOMEM);
170 static int compare_vlcspec(const void *a, const void *b)
172 const VLCcode *sa = a, *sb = b;
173 return (sa->code >> 1) - (sb->code >> 1);
176 * Build VLC decoding tables suitable for use with get_vlc().
178 * @param vlc the context to be initialized
180 * @param table_nb_bits max length of vlc codes to store directly in this table
181 * (Longer codes are delegated to subtables.)
183 * @param nb_codes number of elements in codes[]
185 * @param codes descriptions of the vlc codes
186 * These must be ordered such that codes going into the same subtable are contiguous.
187 * Sorting by VLCcode.code is sufficient, though not necessary.
189 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
190 VLCcode *codes, int flags)
192 int table_size, table_index, index, code_prefix, symbol, subtable_bits;
193 int i, j, k, n, nb, inc;
195 volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2
197 if (table_nb_bits > 30)
198 return AVERROR(EINVAL);
199 table_size = 1 << table_nb_bits;
200 table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
201 ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
204 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
206 /* first pass: map codes and compute auxiliary table sizes */
207 for (i = 0; i < nb_codes; i++) {
209 code = codes[i].code;
210 symbol = codes[i].symbol;
211 ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code);
212 if (n <= table_nb_bits) {
213 /* no need to add another table */
214 j = code >> (32 - table_nb_bits);
215 nb = 1 << (table_nb_bits - n);
217 if (flags & INIT_VLC_OUTPUT_LE) {
218 j = bitswap_32(code);
221 for (k = 0; k < nb; k++) {
222 int bits = table[j][1];
223 int oldsym = table[j][0];
224 ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
225 if ((bits || oldsym) && (bits != n || oldsym != symbol)) {
226 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
227 return AVERROR_INVALIDDATA;
229 table[j][1] = n; //bits
230 table[j][0] = symbol;
234 /* fill auxiliary table recursively */
236 code_prefix = code >> (32 - table_nb_bits);
239 codes[i].code = code << table_nb_bits;
240 for (k = i+1; k < nb_codes; k++) {
241 n = codes[k].bits - table_nb_bits;
244 code = codes[k].code;
245 if (code >> (32 - table_nb_bits) != code_prefix)
248 codes[k].code = code << table_nb_bits;
249 subtable_bits = FFMAX(subtable_bits, n);
251 subtable_bits = FFMIN(subtable_bits, table_nb_bits);
252 j = (flags & INIT_VLC_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
253 table[j][1] = -subtable_bits;
254 ff_dlog(NULL, "%4x: n=%d (subtable)\n",
255 j, codes[i].bits + table_nb_bits);
256 index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
259 /* note: realloc has been done, so reload tables */
260 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
261 table[j][0] = index; //code
262 if (table[j][0] != index) {
263 avpriv_request_sample(NULL, "strange codes");
264 return AVERROR_PATCHWELCOME;
270 for (i = 0; i < table_size; i++) {
271 if (table[i][1] == 0) //bits
272 table[i][0] = -1; //codes
278 static int vlc_common_end(VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes,
279 int flags, VLC *vlc_arg, VLCcode localbuf[LOCALBUF_ELEMS])
281 int ret = build_table(vlc, nb_bits, nb_codes, codes, flags);
283 if (flags & INIT_VLC_USE_NEW_STATIC) {
284 if (vlc->table_size != vlc->table_allocated &&
285 !(flags & (INIT_VLC_STATIC_OVERLONG & ~INIT_VLC_USE_NEW_STATIC)))
286 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
287 av_assert0(ret >= 0);
290 if (codes != localbuf)
293 av_freep(&vlc->table);
300 /* Build VLC decoding tables suitable for use with get_vlc().
302 'nb_bits' sets the decoding table size (2^nb_bits) entries. The
303 bigger it is, the faster is the decoding. But it should not be too
304 big to save memory and L1 cache. '9' is a good compromise.
306 'nb_codes' : number of vlcs codes
308 'bits' : table which gives the size (in bits) of each vlc code.
310 'codes' : table which gives the bit pattern of of each vlc code.
312 'symbols' : table which gives the values to be returned from get_vlc().
314 'xxx_wrap' : give the number of bytes between each entry of the
315 'bits' or 'codes' tables.
317 'xxx_size' : gives the number of bytes of each entry of the 'bits'
318 or 'codes' tables. Currently 1,2 and 4 are supported.
320 'wrap' and 'size' make it possible to use any memory configuration and types
321 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
323 int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
324 const void *bits, int bits_wrap, int bits_size,
325 const void *codes, int codes_wrap, int codes_size,
326 const void *symbols, int symbols_wrap, int symbols_size,
329 VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf;
333 ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc,
338 av_assert0(symbols_size <= 2 || !symbols);
340 #define COPY(condition)\
341 for (i = 0; i < nb_codes; i++) { \
343 GET_DATA(len, bits, i, bits_wrap, bits_size); \
346 if (len > 3*nb_bits || len > 32) { \
347 av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in init_vlc\n", len);\
348 if (buf != localbuf) \
350 return AVERROR(EINVAL); \
353 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
354 if (buf[j].code >= (1LL<<buf[j].bits)) { \
355 av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \
356 "init_vlc\n", buf[j].code, i); \
357 if (buf != localbuf) \
359 return AVERROR(EINVAL); \
361 if (flags & INIT_VLC_INPUT_LE) \
362 buf[j].code = bitswap_32(buf[j].code); \
364 buf[j].code <<= 32 - buf[j].bits; \
366 GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
372 // qsort is the slowest part of init_vlc, and could probably be improved or avoided
373 AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);
374 COPY(len && len <= nb_bits);
377 return vlc_common_end(vlc, nb_bits, nb_codes, buf,
378 flags, vlc_arg, localbuf);
381 int ff_init_vlc_from_lengths(VLC *vlc_arg, int nb_bits, int nb_codes,
382 const int8_t *lens, int lens_wrap,
383 const void *symbols, int symbols_wrap, int symbols_size,
384 int offset, int flags, void *logctx)
386 VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf;
389 int ret, j, len_max = FFMIN(32, 3 * nb_bits);
391 ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc,
397 for (int i = 0; i < nb_codes; i++, lens += lens_wrap) {
404 GET_DATA(sym, symbols, i, symbols_wrap, symbols_size)
407 buf[j].symbol = sym + offset;
408 buf[j++].code = code;
409 } else if (len < 0) {
413 if (len > len_max || code & ((1U << (32 - len)) - 1)) {
414 av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len);
417 code += 1U << (32 - len);
418 if (code > UINT32_MAX + 1ULL) {
419 av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n");
423 return vlc_common_end(vlc, nb_bits, j, buf,
424 flags, vlc_arg, localbuf);
428 return AVERROR_INVALIDDATA;
431 void ff_free_vlc(VLC *vlc)
433 av_freep(&vlc->table);