/* * 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(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER) # if ARCH_ARM && !HAVE_FAST_UNALIGNED # define A32_BITSTREAM_READER # else # define ALT_BITSTREAM_READER //#define LIBMPEG2_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 LIBMPEG2_BITSTREAM_READER uint8_t *buffer_ptr; uint32_t cache; int bit_count; #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;\ int name##_cache= 0;\ # 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)\ {\ SKIP_CACHE(name, gb, num)\ SKIP_COUNTER(name, gb, num)\ }\ # 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 LIBMPEG2_BITSTREAM_READER //libmpeg2 like reader # define MIN_CACHE_BITS 17 # define OPEN_READER(name, gb)\ int name##_bit_count=(gb)->bit_count;\ int name##_cache= (gb)->cache;\ uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\ # define CLOSE_READER(name, gb)\ (gb)->bit_count= name##_bit_count;\ (gb)->cache= name##_cache;\ (gb)->buffer_ptr= name##_buffer_ptr;\ # define UPDATE_CACHE(name, gb)\ if(name##_bit_count >= 0){\ name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \ name##_buffer_ptr+=2;\ name##_bit_count-= 16;\ }\ # define SKIP_CACHE(name, gb, num)\ name##_cache <<= (num);\ # define SKIP_COUNTER(name, gb, num)\ name##_bit_count += (num);\ # define SKIP_BITS(name, gb, num)\ {\ SKIP_CACHE(name, gb, num)\ SKIP_COUNTER(name, gb, num)\ }\ # 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##_cache, num) # define SHOW_SBITS(name, gb, num)\ NEG_SSR32(name##_cache, num) # define GET_CACHE(name, gb)\ ((uint32_t)name##_cache) static inline int get_bits_count(const GetBitContext *s){ return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count; } static inline void skip_bits_long(GetBitContext *s, int n){ OPEN_READER(re, s) re_bit_count += n; re_buffer_ptr += 2*(re_bit_count>>4); re_bit_count &= 15; re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count); UPDATE_CACHE(re, s) CLOSE_READER(re, s) } #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)\ (gb)->bit_count= name##_bit_count;\ (gb)->cache0= name##_cache0;\ (gb)->cache1= name##_cache1;\ (gb)->buffer_ptr= name##_buffer_ptr;\ # define UPDATE_CACHE(name, gb)\ 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;\ }\ #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)\ name##_cache0 <<= (num);\ name##_cache0 |= NEG_USR32(name##_cache1,num);\ name##_cache1 <<= (num); #endif # define SKIP_COUNTER(name, gb, num)\ name##_bit_count += (num);\ # define SKIP_BITS(name, gb, num)\ {\ SKIP_CACHE(name, gb, num)\ SKIP_COUNTER(name, gb, num)\ }\ # 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; } /** * reads 1-17 bits. * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't */ 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 1-17 bits. * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't */ 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); // CLOSE_READER(re, s) 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&0x07); result&= 1; #else result<<= (index&0x07); 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 LIBMPEG2_BITSTREAM_READER s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1)); s->bit_count = 16 + 8*((intptr_t)buffer&1); skip_bits_long(s, 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)\ {\ 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);\ } /** * * 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)\ {\ 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)\ } #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\ {\ 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)\ } /** * 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; } //#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 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); } #endif /* AVCODEC_GET_BITS_H */