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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/atomic.h"
32 #include "libavutil/avassert.h"
33 #include "libavutil/qsort.h"
34 #include "avcodec.h"
35 #include "internal.h"
36 #include "mathops.h"
37 #include "put_bits.h"
38 #include "vlc.h"
39 
40 const uint8_t ff_log2_run[41]={
41  0, 0, 0, 0, 1, 1, 1, 1,
42  2, 2, 2, 2, 3, 3, 3, 3,
43  4, 4, 5, 5, 6, 6, 7, 7,
44  8, 9,10,11,12,13,14,15,
45 16,17,18,19,20,21,22,23,
46 24,
47 };
48 
50 {
51  put_bits(s, s->bit_left & 7, 0);
52 }
53 
54 void avpriv_put_string(PutBitContext *pb, const char *string,
55  int terminate_string)
56 {
57  while (*string) {
58  put_bits(pb, 8, *string);
59  string++;
60  }
61  if (terminate_string)
62  put_bits(pb, 8, 0);
63 }
64 
66 {
67  int words = length >> 4;
68  int bits = length & 15;
69  int i;
70 
71  if (length == 0)
72  return;
73 
74  av_assert0(length <= put_bits_left(pb));
75 
76  if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
77  for (i = 0; i < words; i++)
78  put_bits(pb, 16, AV_RB16(src + 2 * i));
79  } else {
80  for (i = 0; put_bits_count(pb) & 31; i++)
81  put_bits(pb, 8, src[i]);
82  flush_put_bits(pb);
83  memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
84  skip_put_bytes(pb, 2 * words - i);
85  }
86 
87  put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
88 }
89 
90 /* VLC decoding */
91 
92 #define GET_DATA(v, table, i, wrap, size) \
93 { \
94  const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
95  switch(size) { \
96  case 1: \
97  v = *(const uint8_t *)ptr; \
98  break; \
99  case 2: \
100  v = *(const uint16_t *)ptr; \
101  break; \
102  case 4: \
103  v = *(const uint32_t *)ptr; \
104  break; \
105  default: \
106  av_assert1(0); \
107  } \
108 }
109 
110 
111 static int alloc_table(VLC *vlc, int size, int use_static)
112 {
113  int index = vlc->table_size;
114 
115  vlc->table_size += size;
116  if (vlc->table_size > vlc->table_allocated) {
117  if (use_static)
118  abort(); // cannot do anything, init_vlc() is used with too little memory
119  vlc->table_allocated += (1 << vlc->bits);
120  vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
121  if (!vlc->table) {
122  vlc->table_allocated = 0;
123  vlc->table_size = 0;
124  return AVERROR(ENOMEM);
125  }
126  memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
127  }
128  return index;
129 }
130 
131 typedef struct VLCcode {
133  uint16_t symbol;
134  /** codeword, with the first bit-to-be-read in the msb
135  * (even if intended for a little-endian bitstream reader) */
136  uint32_t code;
137 } VLCcode;
138 
139 static int compare_vlcspec(const void *a, const void *b)
140 {
141  const VLCcode *sa = a, *sb = b;
142  return (sa->code >> 1) - (sb->code >> 1);
143 }
144 /**
145  * Build VLC decoding tables suitable for use with get_vlc().
146  *
147  * @param vlc the context to be initialized
148  *
149  * @param table_nb_bits max length of vlc codes to store directly in this table
150  * (Longer codes are delegated to subtables.)
151  *
152  * @param nb_codes number of elements in codes[]
153  *
154  * @param codes descriptions of the vlc codes
155  * These must be ordered such that codes going into the same subtable are contiguous.
156  * Sorting by VLCcode.code is sufficient, though not necessary.
157  */
158 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
159  VLCcode *codes, int flags)
160 {
161  int table_size, table_index, index, code_prefix, symbol, subtable_bits;
162  int i, j, k, n, nb, inc;
163  uint32_t code;
164  volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2
165 
166  table_size = 1 << table_nb_bits;
167  if (table_nb_bits > 30)
168  return -1;
169  table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
170  ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
171  if (table_index < 0)
172  return table_index;
173  table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
174 
175  /* first pass: map codes and compute auxiliary table sizes */
176  for (i = 0; i < nb_codes; i++) {
177  n = codes[i].bits;
178  code = codes[i].code;
179  symbol = codes[i].symbol;
180  ff_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code);
181  if (n <= table_nb_bits) {
182  /* no need to add another table */
183  j = code >> (32 - table_nb_bits);
184  nb = 1 << (table_nb_bits - n);
185  inc = 1;
186  if (flags & INIT_VLC_LE) {
187  j = bitswap_32(code);
188  inc = 1 << n;
189  }
190  for (k = 0; k < nb; k++) {
191  int bits = table[j][1];
192  ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
193  if (bits != 0 && bits != n) {
194  av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
195  return AVERROR_INVALIDDATA;
196  }
197  table[j][1] = n; //bits
198  table[j][0] = symbol;
199  j += inc;
200  }
201  } else {
202  /* fill auxiliary table recursively */
203  n -= table_nb_bits;
204  code_prefix = code >> (32 - table_nb_bits);
205  subtable_bits = n;
206  codes[i].bits = n;
207  codes[i].code = code << table_nb_bits;
208  for (k = i+1; k < nb_codes; k++) {
209  n = codes[k].bits - table_nb_bits;
210  if (n <= 0)
211  break;
212  code = codes[k].code;
213  if (code >> (32 - table_nb_bits) != code_prefix)
214  break;
215  codes[k].bits = n;
216  codes[k].code = code << table_nb_bits;
217  subtable_bits = FFMAX(subtable_bits, n);
218  }
219  subtable_bits = FFMIN(subtable_bits, table_nb_bits);
220  j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
221  table[j][1] = -subtable_bits;
222  ff_dlog(NULL, "%4x: n=%d (subtable)\n",
223  j, codes[i].bits + table_nb_bits);
224  index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
225  if (index < 0)
226  return index;
227  /* note: realloc has been done, so reload tables */
228  table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
229  table[j][0] = index; //code
230  i = k-1;
231  }
232  }
233 
234  for (i = 0; i < table_size; i++) {
235  if (table[i][1] == 0) //bits
236  table[i][0] = -1; //codes
237  }
238 
239  return table_index;
240 }
241 
242 
243 /* Build VLC decoding tables suitable for use with get_vlc().
244 
245  'nb_bits' sets the decoding table size (2^nb_bits) entries. The
246  bigger it is, the faster is the decoding. But it should not be too
247  big to save memory and L1 cache. '9' is a good compromise.
248 
249  'nb_codes' : number of vlcs codes
250 
251  'bits' : table which gives the size (in bits) of each vlc code.
252 
253  'codes' : table which gives the bit pattern of of each vlc code.
254 
255  'symbols' : table which gives the values to be returned from get_vlc().
256 
257  'xxx_wrap' : give the number of bytes between each entry of the
258  'bits' or 'codes' tables.
259 
260  'xxx_size' : gives the number of bytes of each entry of the 'bits'
261  or 'codes' tables. Currently 1,2 and 4 are supported.
262 
263  'wrap' and 'size' make it possible to use any memory configuration and types
264  (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
265 
266  'use_static' should be set to 1 for tables, which should be freed
267  with av_free_static(), 0 if ff_free_vlc() will be used.
268 */
269 int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
270  const void *bits, int bits_wrap, int bits_size,
271  const void *codes, int codes_wrap, int codes_size,
272  const void *symbols, int symbols_wrap, int symbols_size,
273  int flags)
274 {
275  VLCcode *buf;
276  int i, j, ret;
277  VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34
278  VLC localvlc, *vlc;
279 
280  vlc = vlc_arg;
281  vlc->bits = nb_bits;
282  if (flags & INIT_VLC_USE_NEW_STATIC) {
283  av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));
284  buf = localbuf;
285  localvlc = *vlc_arg;
286  vlc = &localvlc;
287  vlc->table_size = 0;
288  } else {
289  vlc->table = NULL;
290  vlc->table_allocated = 0;
291  vlc->table_size = 0;
292 
293  buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode));
294  if (!buf)
295  return AVERROR(ENOMEM);
296  }
297 
298 
299  av_assert0(symbols_size <= 2 || !symbols);
300  j = 0;
301 #define COPY(condition)\
302  for (i = 0; i < nb_codes; i++) { \
303  GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \
304  if (!(condition)) \
305  continue; \
306  if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \
307  av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\
308  if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
309  av_free(buf); \
310  return -1; \
311  } \
312  GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
313  if (buf[j].code >= (1LL<<buf[j].bits)) { \
314  av_log(NULL, AV_LOG_ERROR, "Invalid code %x for %d in 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:40
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:269
static av_always_inline uint32_t bitswap_32(uint32_t x)
Definition: mathops.h:253
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:65
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:49
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:158
#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:227
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:136
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:236
#define FFMIN(a, b)
Definition: common.h:96
uint8_t bits
Definition: bitstream.c:132
uint16_t symbol
Definition: bitstream.c:133
int n
Definition: avisynth_c.h:684
static int compare_vlcspec(const void *a, const void *b)
Definition: bitstream.c:139
#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:54
#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:111
bitstream writer API