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bitstream.c
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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 "libavutil/avassert.h"
32 #include "libavutil/qsort.h"
33 #include "avcodec.h"
34 #include "internal.h"
35 #include "mathops.h"
36 #include "put_bits.h"
37 #include "vlc.h"
38 
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,
45 24,
46 };
47 
49 {
50  put_bits(s, s->bit_left & 7, 0);
51 }
52 
53 void avpriv_put_string(PutBitContext *pb, const char *string,
54  int terminate_string)
55 {
56  while (*string) {
57  put_bits(pb, 8, *string);
58  string++;
59  }
60  if (terminate_string)
61  put_bits(pb, 8, 0);
62 }
63 
65 {
66  int words = length >> 4;
67  int bits = length & 15;
68  int i;
69 
70  if (length == 0)
71  return;
72 
73  av_assert0(length <= put_bits_left(pb));
74 
75  if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
76  for (i = 0; i < words; i++)
77  put_bits(pb, 16, AV_RB16(src + 2 * i));
78  } else {
79  for (i = 0; put_bits_count(pb) & 31; i++)
80  put_bits(pb, 8, src[i]);
81  flush_put_bits(pb);
82  memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
83  skip_put_bytes(pb, 2 * words - i);
84  }
85 
86  put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
87 }
88 
89 /* VLC decoding */
90 
91 #define GET_DATA(v, table, i, wrap, size) \
92 { \
93  const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
94  switch(size) { \
95  case 1: \
96  v = *(const uint8_t *)ptr; \
97  break; \
98  case 2: \
99  v = *(const uint16_t *)ptr; \
100  break; \
101  case 4: \
102  v = *(const uint32_t *)ptr; \
103  break; \
104  default: \
105  av_assert1(0); \
106  } \
107 }
108 
109 
110 static int alloc_table(VLC *vlc, int size, int use_static)
111 {
112  int index = vlc->table_size;
113 
114  vlc->table_size += size;
115  if (vlc->table_size > vlc->table_allocated) {
116  if (use_static)
117  abort(); // cannot do anything, init_vlc() is used with too little memory
118  vlc->table_allocated += (1 << vlc->bits);
119  vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
120  if (!vlc->table) {
121  vlc->table_allocated = 0;
122  vlc->table_size = 0;
123  return AVERROR(ENOMEM);
124  }
125  memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
126  }
127  return index;
128 }
129 
130 typedef struct VLCcode {
132  uint16_t symbol;
133  /** codeword, with the first bit-to-be-read in the msb
134  * (even if intended for a little-endian bitstream reader) */
135  uint32_t code;
136 } VLCcode;
137 
138 static int compare_vlcspec(const void *a, const void *b)
139 {
140  const VLCcode *sa = a, *sb = b;
141  return (sa->code >> 1) - (sb->code >> 1);
142 }
143 /**
144  * Build VLC decoding tables suitable for use with get_vlc().
145  *
146  * @param vlc the context to be initialized
147  *
148  * @param table_nb_bits max length of vlc codes to store directly in this table
149  * (Longer codes are delegated to subtables.)
150  *
151  * @param nb_codes number of elements in codes[]
152  *
153  * @param codes descriptions of the vlc codes
154  * These must be ordered such that codes going into the same subtable are contiguous.
155  * Sorting by VLCcode.code is sufficient, though not necessary.
156  */
157 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
158  VLCcode *codes, int flags)
159 {
160  int table_size, table_index, index, code_prefix, symbol, subtable_bits;
161  int i, j, k, n, nb, inc;
162  uint32_t code;
163  volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2
164 
165  table_size = 1 << table_nb_bits;
166  if (table_nb_bits > 30)
167  return -1;
168  table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
169  ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
170  if (table_index < 0)
171  return table_index;
172  table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
173 
174  /* first pass: map codes and compute auxiliary table sizes */
175  for (i = 0; i < nb_codes; i++) {
176  n = codes[i].bits;
177  code = codes[i].code;
178  symbol = codes[i].symbol;
179  ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code);
180  if (n <= table_nb_bits) {
181  /* no need to add another table */
182  j = code >> (32 - table_nb_bits);
183  nb = 1 << (table_nb_bits - n);
184  inc = 1;
185  if (flags & INIT_VLC_LE) {
186  j = bitswap_32(code);
187  inc = 1 << n;
188  }
189  for (k = 0; k < nb; k++) {
190  int bits = table[j][1];
191  ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
192  if (bits != 0 && bits != n) {
193  av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
194  return AVERROR_INVALIDDATA;
195  }
196  table[j][1] = n; //bits
197  table[j][0] = symbol;
198  j += inc;
199  }
200  } else {
201  /* fill auxiliary table recursively */
202  n -= table_nb_bits;
203  code_prefix = code >> (32 - table_nb_bits);
204  subtable_bits = n;
205  codes[i].bits = n;
206  codes[i].code = code << table_nb_bits;
207  for (k = i+1; k < nb_codes; k++) {
208  n = codes[k].bits - table_nb_bits;
209  if (n <= 0)
210  break;
211  code = codes[k].code;
212  if (code >> (32 - table_nb_bits) != code_prefix)
213  break;
214  codes[k].bits = n;
215  codes[k].code = code << table_nb_bits;
216  subtable_bits = FFMAX(subtable_bits, n);
217  }
218  subtable_bits = FFMIN(subtable_bits, table_nb_bits);
219  j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
220  table[j][1] = -subtable_bits;
221  ff_dlog(NULL, "%4x: n=%d (subtable)\n",
222  j, codes[i].bits + table_nb_bits);
223  index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
224  if (index < 0)
225  return index;
226  /* note: realloc has been done, so reload tables */
227  table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
228  table[j][0] = index; //code
229  i = k-1;
230  }
231  }
232 
233  for (i = 0; i < table_size; i++) {
234  if (table[i][1] == 0) //bits
235  table[i][0] = -1; //codes
236  }
237 
238  return table_index;
239 }
240 
241 
242 /* Build VLC decoding tables suitable for use with get_vlc().
243 
244  'nb_bits' sets the decoding table size (2^nb_bits) entries. The
245  bigger it is, the faster is the decoding. But it should not be too
246  big to save memory and L1 cache. '9' is a good compromise.
247 
248  'nb_codes' : number of vlcs codes
249 
250  'bits' : table which gives the size (in bits) of each vlc code.
251 
252  'codes' : table which gives the bit pattern of of each vlc code.
253 
254  'symbols' : table which gives the values to be returned from get_vlc().
255 
256  'xxx_wrap' : give the number of bytes between each entry of the
257  'bits' or 'codes' tables.
258 
259  'xxx_size' : gives the number of bytes of each entry of the 'bits'
260  or 'codes' tables. Currently 1,2 and 4 are supported.
261 
262  'wrap' and 'size' make it possible to use any memory configuration and types
263  (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
264 
265  'use_static' should be set to 1 for tables, which should be freed
266  with av_free_static(), 0 if ff_free_vlc() will be used.
267 */
268 int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
269  const void *bits, int bits_wrap, int bits_size,
270  const void *codes, int codes_wrap, int codes_size,
271  const void *symbols, int symbols_wrap, int symbols_size,
272  int flags)
273 {
274  VLCcode *buf;
275  int i, j, ret;
276  VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34
277  VLC localvlc, *vlc;
278 
279  vlc = vlc_arg;
280  vlc->bits = nb_bits;
281  if (flags & INIT_VLC_USE_NEW_STATIC) {
282  av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));
283  buf = localbuf;
284  localvlc = *vlc_arg;
285  vlc = &localvlc;
286  vlc->table_size = 0;
287  } else {
288  vlc->table = NULL;
289  vlc->table_allocated = 0;
290  vlc->table_size = 0;
291 
292  buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode));
293  if (!buf)
294  return AVERROR(ENOMEM);
295  }
296 
297 
298  av_assert0(symbols_size <= 2 || !symbols);
299  j = 0;
300 #define COPY(condition)\
301  for (i = 0; i < nb_codes; i++) { \
302  GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \
303  if (!(condition)) \
304  continue; \
305  if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \
306  av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\
307  if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
308  av_free(buf); \
309  return -1; \
310  } \
311  GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
312  if (buf[j].code >= (1LL<<buf[j].bits)) { \
313  av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \
314  "init_vlc\n", buf[j].code, i); \
315  if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
316  av_free(buf); \
317  return -1; \
318  } \
319  if (flags & INIT_VLC_LE) \
320  buf[j].code = bitswap_32(buf[j].code); \
321  else \
322  buf[j].code <<= 32 - buf[j].bits; \
323  if (symbols) \
324  GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
325  else \
326  buf[j].symbol = i; \
327  j++; \
328  }
329  COPY(buf[j].bits > nb_bits);
330  // qsort is the slowest part of init_vlc, and could probably be improved or avoided
331  AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);
332  COPY(buf[j].bits && buf[j].bits <= nb_bits);
333  nb_codes = j;
334 
335  ret = build_table(vlc, nb_bits, nb_codes, buf, flags);
336 
337  if (flags & INIT_VLC_USE_NEW_STATIC) {
338  if(vlc->table_size != vlc->table_allocated)
339  av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
340 
341  av_assert0(ret >= 0);
342  *vlc_arg = *vlc;
343  } else {
344  av_free(buf);
345  if (ret < 0) {
346  av_freep(&vlc->table);
347  return ret;
348  }
349  }
350  return 0;
351 }
352 
353 
354 void ff_free_vlc(VLC *vlc)
355 {
356  av_freep(&vlc->table);
357 }
#define NULL
Definition: coverity.c:32
const uint8_t ff_log2_run[41]
Definition: bitstream.c:39
int table_size
Definition: vlc.h:29
const char * s
Definition: avisynth_c.h:768
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
#define av_realloc_f(p, o, n)
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:206
int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags)
Definition: bitstream.c:268
static av_always_inline uint32_t bitswap_32(uint32_t x)
Definition: mathops.h:243
const char * b
Definition: vf_curves.c:113
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
Copy the content of src to the bitstream.
Definition: bitstream.c:64
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:48
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:87
static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, VLCcode *codes, int flags)
Build VLC decoding tables suitable for use with get_vlc().
Definition: bitstream.c:157
#define src
Definition: vp8dsp.c:254
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
uint8_t bits
Definition: crc.c:296
uint8_t
#define COPY(condition)
static int flags
Definition: log.c:57
#define ff_dlog(a,...)
ptrdiff_t size
Definition: opengl_enc.c:101
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static uint8_t * put_bits_ptr(PutBitContext *s)
Return the pointer to the byte where the bitstream writer will put the next bit.
Definition: put_bits.h:249
static int put_bits_left(PutBitContext *s)
Definition: put_bits.h:93
#define AVERROR(e)
Definition: error.h:43
static const struct endianess table[]
uint32_t code
codeword, with the first bit-to-be-read in the msb (even if intended for a little-endian bitstream re...
Definition: bitstream.c:135
simple assert() macros that are a bit more flexible than ISO C assert().
GLsizei GLsizei * length
Definition: opengl_enc.c:115
#define FFMAX(a, b)
Definition: common.h:94
Definition: vlc.h:26
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:85
static void skip_put_bytes(PutBitContext *s, int n)
Skip the given number of bytes.
Definition: put_bits.h:258
#define FFMIN(a, b)
Definition: common.h:96
uint8_t bits
Definition: bitstream.c:131
uint16_t symbol
Definition: bitstream.c:132
int n
Definition: avisynth_c.h:684
static int compare_vlcspec(const void *a, const void *b)
Definition: bitstream.c:138
#define FF_ARRAY_ELEMS(a)
#define INIT_VLC_LE
Definition: vlc.h:54
int bits
Definition: vlc.h:27
int table_allocated
Definition: vlc.h:29
Libavcodec external API header.
int bit_left
Definition: put_bits.h:37
void * buf
Definition: avisynth_c.h:690
int index
Definition: gxfenc.c:89
common internal api header.
static void flush_put_bits(PutBitContext *s)
Pad the end of the output stream with zeros.
Definition: put_bits.h:101
#define INIT_VLC_USE_NEW_STATIC
Definition: vlc.h:55
static const unsigned code_prefix[]
Definition: qdmc.c:75
#define av_free(p)
VLC_TYPE(* table)[2]
code, bits
Definition: vlc.h:28
void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string)
Put the string string in the bitstream.
Definition: bitstream.c:53
#define av_freep(p)
#define VLC_TYPE
Definition: vlc.h:24
#define av_malloc_array(a, b)
void ff_free_vlc(VLC *vlc)
Definition: bitstream.c:354
#define AV_QSORT(p, num, type, cmp)
Quicksort This sort is fast, and fully inplace but not stable and it is possible to construct input t...
Definition: qsort.h:33
for(j=16;j >0;--j)
static int alloc_table(VLC *vlc, int size, int use_static)
Definition: bitstream.c:110
bitstream writer API