| /* |
| * 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 <stdlib.h> |
| #include <assert.h> |
| #include "libavutil/bswap.h" |
| #include "libavutil/common.h" |
| #include "libavutil/intreadwrite.h" |
| #include "libavutil/log.h" |
| #include "mathops.h" |
| |
| #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER) |
| # define ALT_BITSTREAM_READER |
| #endif |
| |
| #if !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER) |
| # if ARCH_ARM && !HAVE_FAST_UNALIGNED |
| # define A32_BITSTREAM_READER |
| # else |
| # define ALT_BITSTREAM_READER |
| //#define A32_BITSTREAM_READER |
| # endif |
| #endif |
| |
| /* bit input */ |
| /* buffer, buffer_end and size_in_bits must be present and used by every reader */ |
| typedef struct GetBitContext { |
| const uint8_t *buffer, *buffer_end; |
| #ifdef ALT_BITSTREAM_READER |
| int index; |
| #elif defined A32_BITSTREAM_READER |
| uint32_t *buffer_ptr; |
| uint32_t cache0; |
| uint32_t cache1; |
| int bit_count; |
| #endif |
| int size_in_bits; |
| } 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) |
| loads gb into local variables |
| |
| CLOSE_READER(name, gb) |
| stores local vars in gb |
| |
| UPDATE_CACHE(name, gb) |
| refills 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_CACHE(name, gb, num) |
| will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing |
| |
| LAST_SKIP_BITS(name, gb, num) |
| is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER |
| |
| for examples see get_bits, show_bits, skip_bits, get_vlc |
| */ |
| |
| #ifdef ALT_BITSTREAM_READER |
| # define MIN_CACHE_BITS 25 |
| |
| # define OPEN_READER(name, gb) \ |
| unsigned int name##_index = (gb)->index; \ |
| av_unused unsigned int name##_cache |
| |
| # define CLOSE_READER(name, gb) (gb)->index = name##_index |
| |
| # ifdef ALT_BITSTREAM_READER_LE |
| # define UPDATE_CACHE(name, gb) \ |
| name##_cache = AV_RL32(((const uint8_t *)(gb)->buffer)+(name##_index>>3)) >> (name##_index&0x07) |
| |
| # define SKIP_CACHE(name, gb, num) name##_cache >>= (num) |
| # else |
| # define UPDATE_CACHE(name, gb) \ |
| name##_cache = AV_RB32(((const uint8_t *)(gb)->buffer)+(name##_index>>3)) << (name##_index&0x07) |
| |
| # define SKIP_CACHE(name, gb, num) name##_cache <<= (num) |
| # endif |
| |
| // FIXME name? |
| # define SKIP_COUNTER(name, gb, num) name##_index += (num) |
| |
| # 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) |
| # define LAST_SKIP_CACHE(name, gb, num) |
| |
| # ifdef ALT_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){ |
| s->index += n; |
| } |
| |
| #elif defined A32_BITSTREAM_READER |
| |
| # define MIN_CACHE_BITS 32 |
| |
| # define OPEN_READER(name, gb) \ |
| int name##_bit_count = (gb)->bit_count; \ |
| uint32_t name##_cache0 = (gb)->cache0; \ |
| uint32_t name##_cache1 = (gb)->cache1; \ |
| uint32_t *name##_buffer_ptr = (gb)->buffer_ptr |
| |
| # define CLOSE_READER(name, gb) do { \ |
| (gb)->bit_count = name##_bit_count; \ |
| (gb)->cache0 = name##_cache0; \ |
| (gb)->cache1 = name##_cache1; \ |
| (gb)->buffer_ptr = name##_buffer_ptr; \ |
| } while (0) |
| |
| # define UPDATE_CACHE(name, gb) do { \ |
| if(name##_bit_count > 0){ \ |
| const uint32_t next = av_be2ne32(*name##_buffer_ptr); \ |
| name##_cache0 |= NEG_USR32(next, name##_bit_count); \ |
| name##_cache1 |= next << name##_bit_count; \ |
| name##_buffer_ptr++; \ |
| name##_bit_count -= 32; \ |
| } \ |
| } while (0) |
| |
| #if ARCH_X86 |
| # define SKIP_CACHE(name, gb, num) \ |
| __asm__("shldl %2, %1, %0 \n\t" \ |
| "shll %2, %1 \n\t" \ |
| : "+r" (name##_cache0), "+r" (name##_cache1) \ |
| : "Ic" ((uint8_t)(num))) |
| #else |
| # define SKIP_CACHE(name, gb, num) do { \ |
| name##_cache0 <<= (num); \ |
| name##_cache0 |= NEG_USR32(name##_cache1,num); \ |
| name##_cache1 <<= (num); \ |
| } while (0) |
| #endif |
| |
| # define SKIP_COUNTER(name, gb, num) name##_bit_count += (num) |
| |
| # 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_BITS(name, gb, num) |
| # define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num) |
| |
| # define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache0, num) |
| |
| # define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache0, num) |
| |
| # define GET_CACHE(name, gb) name##_cache0 |
| |
| static inline int get_bits_count(const GetBitContext *s) { |
| return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count; |
| } |
| |
| static inline void skip_bits_long(GetBitContext *s, int n){ |
| OPEN_READER(re, s); |
| re_bit_count += n; |
| re_buffer_ptr += re_bit_count>>5; |
| re_bit_count &= 31; |
| re_cache0 = av_be2ne32(re_buffer_ptr[-1]) << re_bit_count; |
| re_cache1 = 0; |
| UPDATE_CACHE(re, s); |
| CLOSE_READER(re, s); |
| } |
| |
| #endif |
| |
| /** |
| * read mpeg1 dc style vlc (sign bit + mantisse with no MSB). |
| * if MSB not set it is negative |
| * @param n length in bits |
| * @author BERO |
| */ |
| 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); |
| 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); |
| UPDATE_CACHE(re, s); |
| tmp = SHOW_UBITS(re, s, n); |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| return tmp; |
| } |
| |
| /** |
| * Shows 1-25 bits. |
| */ |
| static inline unsigned int show_bits(GetBitContext *s, int n){ |
| register int tmp; |
| OPEN_READER(re, s); |
| UPDATE_CACHE(re, s); |
| tmp = SHOW_UBITS(re, s, n); |
| return tmp; |
| } |
| |
| static inline void skip_bits(GetBitContext *s, int n){ |
| //Note gcc seems to optimize this to s->index+=n for the ALT_READER :)) |
| 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){ |
| #ifdef ALT_BITSTREAM_READER |
| unsigned int index = s->index; |
| uint8_t result = s->buffer[index>>3]; |
| #ifdef ALT_BITSTREAM_READER_LE |
| result >>= index & 7; |
| result &= 1; |
| #else |
| result <<= index & 7; |
| result >>= 8 - 1; |
| #endif |
| index++; |
| s->index = index; |
| |
| return result; |
| #else |
| return get_bits(s, 1); |
| #endif |
| } |
| |
| static inline unsigned int show_bits1(GetBitContext *s){ |
| return show_bits(s, 1); |
| } |
| |
| static inline void skip_bits1(GetBitContext *s){ |
| skip_bits(s, 1); |
| } |
| |
| /** |
| * reads 0-32 bits. |
| */ |
| static inline unsigned int get_bits_long(GetBitContext *s, int n){ |
| if (n <= MIN_CACHE_BITS) return get_bits(s, n); |
| else { |
| #ifdef ALT_BITSTREAM_READER_LE |
| int ret = get_bits(s, 16); |
| return ret | (get_bits(s, n-16) << 16); |
| #else |
| int ret = get_bits(s, 16) << (n-16); |
| return ret | get_bits(s, n-16); |
| #endif |
| } |
| } |
| |
| /** |
| * reads 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); |
| } |
| |
| /** |
| * shows 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; |
| } |
| |
| /** |
| * init GetBitContext. |
| * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then 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 |
| * |
| * While GetBitContext stores the buffer size, for performance reasons you are |
| * responsible for checking for the buffer end yourself (take advantage of the padding)! |
| */ |
| static inline void init_get_bits(GetBitContext *s, |
| const uint8_t *buffer, int bit_size) |
| { |
| int buffer_size = (bit_size+7)>>3; |
| if (buffer_size < 0 || bit_size < 0) { |
| buffer_size = bit_size = 0; |
| buffer = NULL; |
| } |
| |
| s->buffer = buffer; |
| s->size_in_bits = bit_size; |
| s->buffer_end = buffer + buffer_size; |
| #ifdef ALT_BITSTREAM_READER |
| s->index = 0; |
| #elif defined A32_BITSTREAM_READER |
| s->buffer_ptr = (uint32_t*)((intptr_t)buffer & ~3); |
| s->bit_count = 32 + 8*((intptr_t)buffer & 3); |
| skip_bits_long(s, 0); |
| #endif |
| } |
| |
| static inline void align_get_bits(GetBitContext *s) |
| { |
| int n = -get_bits_count(s) & 7; |
| if (n) skip_bits(s, n); |
| } |
| |
| #define init_vlc(vlc, nb_bits, nb_codes, \ |
| bits, bits_wrap, bits_size, \ |
| codes, codes_wrap, codes_size, \ |
| flags) \ |
| init_vlc_sparse(vlc, nb_bits, nb_codes, \ |
| bits, bits_wrap, bits_size, \ |
| codes, codes_wrap, codes_size, \ |
| NULL, 0, 0, flags) |
| |
| int 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); |
| #define INIT_VLC_LE 2 |
| #define INIT_VLC_USE_NEW_STATIC 4 |
| void free_vlc(VLC *vlc); |
| |
| #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) |
| |
| |
| /** |
| * parses a vlc code, faster then get_vlc() |
| * @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, 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, 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, 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 */ |
