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Diffstat (limited to 'ffmpeg/libavcodec/get_bits.h')
| -rw-r--r-- | ffmpeg/libavcodec/get_bits.h | 631 |
1 files changed, 631 insertions, 0 deletions
diff --git a/ffmpeg/libavcodec/get_bits.h b/ffmpeg/libavcodec/get_bits.h new file mode 100644 index 0000000..f16a508 --- /dev/null +++ b/ffmpeg/libavcodec/get_bits.h @@ -0,0 +1,631 @@ +/* + * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * bitstream reader API header. + */ + +#ifndef AVCODEC_GET_BITS_H +#define AVCODEC_GET_BITS_H + +#include <stdint.h> + +#include "libavutil/common.h" +#include "libavutil/intreadwrite.h" +#include "libavutil/log.h" +#include "libavutil/avassert.h" +#include "mathops.h" + +/* + * Safe bitstream reading: + * optionally, the get_bits API can check to ensure that we + * don't read past input buffer boundaries. This is protected + * with CONFIG_SAFE_BITSTREAM_READER at the global level, and + * then below that with UNCHECKED_BITSTREAM_READER at the per- + * decoder level. This means that decoders that check internally + * can "#define UNCHECKED_BITSTREAM_READER 1" to disable + * overread checks. + * Boundary checking causes a minor performance penalty so for + * applications that won't want/need this, it can be disabled + * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". + */ +#ifndef UNCHECKED_BITSTREAM_READER +#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER +#endif + +typedef struct GetBitContext { + const uint8_t *buffer, *buffer_end; + int index; + int size_in_bits; + int size_in_bits_plus8; +} GetBitContext; + +#define VLC_TYPE int16_t + +typedef struct VLC { + int bits; + VLC_TYPE (*table)[2]; ///< code, bits + int table_size, table_allocated; +} VLC; + +typedef struct RL_VLC_ELEM { + int16_t level; + int8_t len; + uint8_t run; +} RL_VLC_ELEM; + +/* Bitstream reader API docs: + * name + * arbitrary name which is used as prefix for the internal variables + * + * gb + * getbitcontext + * + * OPEN_READER(name, gb) + * load gb into local variables + * + * CLOSE_READER(name, gb) + * store local vars in gb + * + * UPDATE_CACHE(name, gb) + * Refill the internal cache from the bitstream. + * After this call at least MIN_CACHE_BITS will be available. + * + * GET_CACHE(name, gb) + * Will output the contents of the internal cache, + * next bit is MSB of 32 or 64 bit (FIXME 64bit). + * + * SHOW_UBITS(name, gb, num) + * Will return the next num bits. + * + * SHOW_SBITS(name, gb, num) + * Will return the next num bits and do sign extension. + * + * SKIP_BITS(name, gb, num) + * Will skip over the next num bits. + * Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER. + * + * SKIP_CACHE(name, gb, num) + * Will remove the next num bits from the cache (note SKIP_COUNTER + * MUST be called before UPDATE_CACHE / CLOSE_READER). + * + * SKIP_COUNTER(name, gb, num) + * Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS). + * + * LAST_SKIP_BITS(name, gb, num) + * Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER. + * + * For examples see get_bits, show_bits, skip_bits, get_vlc. + */ + +#ifdef LONG_BITSTREAM_READER +# define MIN_CACHE_BITS 32 +#else +# define MIN_CACHE_BITS 25 +#endif + +#if UNCHECKED_BITSTREAM_READER +#define OPEN_READER(name, gb) \ + unsigned int name ## _index = (gb)->index; \ + unsigned int av_unused name ## _cache + +#define HAVE_BITS_REMAINING(name, gb) 1 +#else +#define OPEN_READER(name, gb) \ + unsigned int name ## _index = (gb)->index; \ + unsigned int av_unused name ## _cache = 0; \ + unsigned int av_unused name ## _size_plus8 = (gb)->size_in_bits_plus8 + +#define HAVE_BITS_REMAINING(name, gb) name ## _index < name ## _size_plus8 +#endif + +#define CLOSE_READER(name, gb) (gb)->index = name ## _index + +#ifdef BITSTREAM_READER_LE + +# ifdef LONG_BITSTREAM_READER +# define UPDATE_CACHE(name, gb) name ## _cache = \ + AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) +# else +# define UPDATE_CACHE(name, gb) name ## _cache = \ + AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) +# endif + +# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) + +#else + +# ifdef LONG_BITSTREAM_READER +# define UPDATE_CACHE(name, gb) name ## _cache = \ + AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7)) +# else +# define UPDATE_CACHE(name, gb) name ## _cache = \ + AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) +# endif + +# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) + +#endif + +#if UNCHECKED_BITSTREAM_READER +# define SKIP_COUNTER(name, gb, num) name ## _index += (num) +#else +# define SKIP_COUNTER(name, gb, num) \ + name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) +#endif + +#define SKIP_BITS(name, gb, num) \ + do { \ + SKIP_CACHE(name, gb, num); \ + SKIP_COUNTER(name, gb, num); \ + } while (0) + +#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) + +#ifdef BITSTREAM_READER_LE +# define SHOW_UBITS(name, gb, num) zero_extend(name ## _cache, num) +# define SHOW_SBITS(name, gb, num) sign_extend(name ## _cache, num) +#else +# define SHOW_UBITS(name, gb, num) NEG_USR32(name ## _cache, num) +# define SHOW_SBITS(name, gb, num) NEG_SSR32(name ## _cache, num) +#endif + +#define GET_CACHE(name, gb) ((uint32_t) name ## _cache) + +static inline int get_bits_count(const GetBitContext *s) +{ + return s->index; +} + +static inline void skip_bits_long(GetBitContext *s, int n) +{ +#if UNCHECKED_BITSTREAM_READER + s->index += n; +#else + s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); +#endif +} + +/** + * read mpeg1 dc style vlc (sign bit + mantisse with no MSB). + * if MSB not set it is negative + * @param n length in bits + */ +static inline int get_xbits(GetBitContext *s, int n) +{ + register int sign; + register int32_t cache; + OPEN_READER(re, s); + UPDATE_CACHE(re, s); + cache = GET_CACHE(re, s); + sign = ~cache >> 31; + LAST_SKIP_BITS(re, s, n); + CLOSE_READER(re, s); + return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; +} + +static inline int get_sbits(GetBitContext *s, int n) +{ + register int tmp; + OPEN_READER(re, s); + av_assert2(n>0 && n<=25); + UPDATE_CACHE(re, s); + tmp = SHOW_SBITS(re, s, n); + LAST_SKIP_BITS(re, s, n); + CLOSE_READER(re, s); + return tmp; +} + +/** + * Read 1-25 bits. + */ +static inline unsigned int get_bits(GetBitContext *s, int n) +{ + register int tmp; + OPEN_READER(re, s); + av_assert2(n>0 && n<=25); + UPDATE_CACHE(re, s); + tmp = SHOW_UBITS(re, s, n); + LAST_SKIP_BITS(re, s, n); + CLOSE_READER(re, s); + return tmp; +} + +/** + * Show 1-25 bits. + */ +static inline unsigned int show_bits(GetBitContext *s, int n) +{ + register int tmp; + OPEN_READER(re, s); + av_assert2(n>0 && n<=25); + UPDATE_CACHE(re, s); + tmp = SHOW_UBITS(re, s, n); + return tmp; +} + +static inline void skip_bits(GetBitContext *s, int n) +{ + OPEN_READER(re, s); + UPDATE_CACHE(re, s); + LAST_SKIP_BITS(re, s, n); + CLOSE_READER(re, s); +} + +static inline unsigned int get_bits1(GetBitContext *s) +{ + unsigned int index = s->index; + uint8_t result = s->buffer[index >> 3]; +#ifdef BITSTREAM_READER_LE + result >>= index & 7; + result &= 1; +#else + result <<= index & 7; + result >>= 8 - 1; +#endif +#if !UNCHECKED_BITSTREAM_READER + if (s->index < s->size_in_bits_plus8) +#endif + index++; + s->index = index; + + return result; +} + +static inline unsigned int show_bits1(GetBitContext *s) +{ + return show_bits(s, 1); +} + +static inline void skip_bits1(GetBitContext *s) +{ + skip_bits(s, 1); +} + +/** + * Read 0-32 bits. + */ +static inline unsigned int get_bits_long(GetBitContext *s, int n) +{ + if (!n) { + return 0; + } else if (n <= MIN_CACHE_BITS) { + return get_bits(s, n); + } else { +#ifdef BITSTREAM_READER_LE + unsigned ret = get_bits(s, 16); + return ret | (get_bits(s, n - 16) << 16); +#else + unsigned ret = get_bits(s, 16) << (n - 16); + return ret | get_bits(s, n - 16); +#endif + } +} + +/** + * Read 0-64 bits. + */ +static inline uint64_t get_bits64(GetBitContext *s, int n) +{ + if (n <= 32) { + return get_bits_long(s, n); + } else { +#ifdef BITSTREAM_READER_LE + uint64_t ret = get_bits_long(s, 32); + return ret | (uint64_t) get_bits_long(s, n - 32) << 32; +#else + uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; + return ret | get_bits_long(s, 32); +#endif + } +} + +/** + * Read 0-32 bits as a signed integer. + */ +static inline int get_sbits_long(GetBitContext *s, int n) +{ + return sign_extend(get_bits_long(s, n), n); +} + +/** + * Show 0-32 bits. + */ +static inline unsigned int show_bits_long(GetBitContext *s, int n) +{ + if (n <= MIN_CACHE_BITS) { + return show_bits(s, n); + } else { + GetBitContext gb = *s; + return get_bits_long(&gb, n); + } +} + +static inline int check_marker(GetBitContext *s, const char *msg) +{ + int bit = get_bits1(s); + if (!bit) + av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg); + + return bit; +} + +/** + * Initialize GetBitContext. + * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes + * larger than the actual read bits because some optimized bitstream + * readers read 32 or 64 bit at once and could read over the end + * @param bit_size the size of the buffer in bits + * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. + */ +static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, + int bit_size) +{ + int buffer_size; + int ret = 0; + + if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) { + buffer_size = bit_size = 0; + buffer = NULL; + ret = AVERROR_INVALIDDATA; + } + + buffer_size = (bit_size + 7) >> 3; + + s->buffer = buffer; + s->size_in_bits = bit_size; + s->size_in_bits_plus8 = bit_size + 8; + s->buffer_end = buffer + buffer_size; + s->index = 0; + + return ret; +} + +/** + * Initialize GetBitContext. + * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes + * larger than the actual read bits because some optimized bitstream + * readers read 32 or 64 bit at once and could read over the end + * @param byte_size the size of the buffer in bytes + * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. + */ +static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, + int byte_size) +{ + if (byte_size > INT_MAX / 8 || byte_size < 0) + byte_size = -1; + return init_get_bits(s, buffer, byte_size * 8); +} + +static inline const uint8_t *align_get_bits(GetBitContext *s) +{ + int n = -get_bits_count(s) & 7; + if (n) + skip_bits(s, n); + return s->buffer + (s->index >> 3); +} + +#define init_vlc(vlc, nb_bits, nb_codes, \ + bits, bits_wrap, bits_size, \ + codes, codes_wrap, codes_size, \ + flags) \ + ff_init_vlc_sparse(vlc, nb_bits, nb_codes, \ + bits, bits_wrap, bits_size, \ + codes, codes_wrap, codes_size, \ + NULL, 0, 0, flags) + +int ff_init_vlc_sparse(VLC *vlc, 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); +void ff_free_vlc(VLC *vlc); + +#define INIT_VLC_LE 2 +#define INIT_VLC_USE_NEW_STATIC 4 + +#define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \ + do { \ + static VLC_TYPE table[static_size][2]; \ + (vlc)->table = table; \ + (vlc)->table_allocated = static_size; \ + init_vlc(vlc, bits, a, b, c, d, e, f, g, INIT_VLC_USE_NEW_STATIC); \ + } while (0) + +/** + * If the vlc code is invalid and max_depth=1, then no bits will be removed. + * If the vlc code is invalid and max_depth>1, then the number of bits removed + * is undefined. + */ +#define GET_VLC(code, name, gb, table, bits, max_depth) \ + do { \ + int n, nb_bits; \ + unsigned int index; \ + \ + index = SHOW_UBITS(name, gb, bits); \ + code = table[index][0]; \ + n = table[index][1]; \ + \ + if (max_depth > 1 && n < 0) { \ + LAST_SKIP_BITS(name, gb, bits); \ + UPDATE_CACHE(name, gb); \ + \ + nb_bits = -n; \ + \ + index = SHOW_UBITS(name, gb, nb_bits) + code; \ + code = table[index][0]; \ + n = table[index][1]; \ + if (max_depth > 2 && n < 0) { \ + LAST_SKIP_BITS(name, gb, nb_bits); \ + UPDATE_CACHE(name, gb); \ + \ + nb_bits = -n; \ + \ + index = SHOW_UBITS(name, gb, nb_bits) + code; \ + code = table[index][0]; \ + n = table[index][1]; \ + } \ + } \ + SKIP_BITS(name, gb, n); \ + } while (0) + +#define GET_RL_VLC(level, run, name, gb, table, bits, \ + max_depth, need_update) \ + do { \ + int n, nb_bits; \ + unsigned int index; \ + \ + index = SHOW_UBITS(name, gb, bits); \ + level = table[index].level; \ + n = table[index].len; \ + \ + if (max_depth > 1 && n < 0) { \ + SKIP_BITS(name, gb, bits); \ + if (need_update) { \ + UPDATE_CACHE(name, gb); \ + } \ + \ + nb_bits = -n; \ + \ + index = SHOW_UBITS(name, gb, nb_bits) + level; \ + level = table[index].level; \ + n = table[index].len; \ + } \ + run = table[index].run; \ + SKIP_BITS(name, gb, n); \ + } while (0) + +/** + * Parse a vlc code. + * @param bits is the number of bits which will be read at once, must be + * identical to nb_bits in init_vlc() + * @param max_depth is the number of times bits bits must be read to completely + * read the longest vlc code + * = (max_vlc_length + bits - 1) / bits + */ +static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], + int bits, int max_depth) +{ + int code; + + OPEN_READER(re, s); + UPDATE_CACHE(re, s); + + GET_VLC(code, re, s, table, bits, max_depth); + + CLOSE_READER(re, s); + + return code; +} + +static inline int decode012(GetBitContext *gb) +{ + int n; + n = get_bits1(gb); + if (n == 0) + return 0; + else + return get_bits1(gb) + 1; +} + +static inline int decode210(GetBitContext *gb) +{ + if (get_bits1(gb)) + return 0; + else + return 2 - get_bits1(gb); +} + +static inline int get_bits_left(GetBitContext *gb) +{ + return gb->size_in_bits - get_bits_count(gb); +} + +//#define TRACE + +#ifdef TRACE +static inline void print_bin(int bits, int n) +{ + int i; + + for (i = n - 1; i >= 0; i--) + av_log(NULL, AV_LOG_DEBUG, "%d", (bits >> i) & 1); + for (i = n; i < 24; i++) + av_log(NULL, AV_LOG_DEBUG, " "); +} + +static inline int get_bits_trace(GetBitContext *s, int n, const char *file, + const char *func, int line) +{ + int r = get_bits(s, n); + + print_bin(r, n); + av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n", + r, n, r, get_bits_count(s) - n, file, func, line); + + return r; +} + +static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], + int bits, int max_depth, const char *file, + const char *func, int line) +{ + int show = show_bits(s, 24); + int pos = get_bits_count(s); + int r = get_vlc2(s, table, bits, max_depth); + int len = get_bits_count(s) - pos; + int bits2 = show >> (24 - len); + + print_bin(bits2, len); + + av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", + bits2, len, r, pos, file, func, line); + + return r; +} + +static inline int get_xbits_trace(GetBitContext *s, int n, const char *file, + const char *func, int line) +{ + int show = show_bits(s, n); + int r = get_xbits(s, n); + + print_bin(show, n); + av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n", + show, n, r, get_bits_count(s) - n, file, func, line); + + return r; +} + +#define get_bits(s, n) get_bits_trace(s , n, __FILE__, __PRETTY_FUNCTION__, __LINE__) +#define get_bits1(s) get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__) +#define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__) + +#define get_vlc(s, vlc) get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__) +#define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__) + +#define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__) + +#else //TRACE +#define tprintf(p, ...) { } +#endif + +#endif /* AVCODEC_GET_BITS_H */ |