/* * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; 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; \ unsigned int av_unused 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) 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 */