bitstream.h

tcpmp播放器的flv插件

        (gb)->bit_count= name##_bit_count;\
        (gb)->cache= name##_cache;\
        (gb)->buffer_ptr= name##_buffer_ptr;\

#ifdef LIBMPEG2_BITSTREAM_READER_HACK

#   define UPDATE_CACHE(name, gb)\
    if(name##_bit_count >= 0){\
        name##_cache+= (int)be2me_16(*(uint16_t*)name##_buffer_ptr) << name##_bit_count;\
        name##_buffer_ptr += 2;\
        name##_bit_count-= 16;\
    }\

#else

#   define UPDATE_CACHE(name, gb)\
    if(name##_bit_count >= 0){\
        name##_cache+= ((name##_buffer_ptr[0]<<8) + name##_buffer_ptr[1]) << name##_bit_count;\
        name##_buffer_ptr+=2;\
        name##_bit_count-= 16;\
    }\

#endif

#   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(GetBitContext *s){
    return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
}

#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= be2me_32( *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 defined(ARCH_X86) || defined(ARCH_X86_64)
#   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(GetBitContext *s){
    return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
}

#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 tmp;
    register int32_t cache;
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)
    cache = GET_CACHE(re,s);
    if ((int32_t)cache<0) { //MSB=1
        tmp = NEG_USR32(cache,n);
    } else {
    //   tmp = (-1<<n) | NEG_USR32(cache,n) + 1; mpeg12.c algo
    //   tmp = - (NEG_USR32(cache,n) ^ ((1 << n) - 1)); h263.c algo
        tmp = - NEG_USR32(~cache,n);
    }
    LAST_SKIP_BITS(re, s, n)
    CLOSE_READER(re, s)
    return tmp;
}

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 0-17 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;
}

unsigned int get_bits_long(GetBitContext *s, int n);

/**
 * shows 0-17 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;
}

unsigned int show_bits_long(GetBitContext *s, int n);

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
    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);
}

/**
 * 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
 */
static inline void init_get_bits(GetBitContext *s,
                   const uint8_t *buffer, int bit_size)
{
    const int buffer_size= (bit_size+7)>>3;

    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
#ifdef LIBMPEG2_BITSTREAM_READER_HACK
  if ((int)buffer&1) {
     /* word alignment */
    s->cache = (*buffer++)<<24;
    s->buffer_ptr = buffer;
    s->bit_count = 16-8;
  } else
#endif
  {
    s->buffer_ptr = buffer;
    s->bit_count = 16;
    s->cache = 0;
  }
#elif defined A32_BITSTREAM_READER
    s->buffer_ptr = (uint32_t*)buffer;
    s->bit_count = 32;
    s->cache0 = 0;
    s->cache1 = 0;
#endif
    {
        OPEN_READER(re, s)
        UPDATE_CACHE(re, s)
        UPDATE_CACHE(re, s)
        CLOSE_READER(re, s)
    }
#ifdef A32_BITSTREAM_READER
    s->cache1 = 0;
#endif
}

int check_marker(GetBitContext *s, const char *msg);
void align_get_bits(GetBitContext *s);
int init_vlc(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,
             int flags);
#define INIT_VLC_USE_STATIC 1
#define INIT_VLC_LE         2
void free_vlc(VLC *vlc);

/**
 *
 * if the vlc code is invalid and max_depth=1 than no bits will be removed
 * if the vlc code is invalid and max_depth>1 than the number of bits removed
 * is undefined
 */
#define GET_VLC(code, name, gb, table, bits, max_depth)\
{\
    int n, index, nb_bits;\
\
    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, index, nb_bits;\
\
    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)\
}

// deprecated, dont use get_vlc for new code, use get_vlc2 instead or use GET_VLC directly
static inline int get_vlc(GetBitContext *s, VLC *vlc)
{
    int code;
    VLC_TYPE (*table)[2]= vlc->table;
    
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)

    GET_VLC(code, re, s, table, vlc->bits, 3)    

    CLOSE_READER(re, s)
    return code;
}

/**
 * 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 readed to completly
 *                  read the longest vlc code 
 *                  = (max_vlc_length + bits - 1) / bits
 */
static 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
#include "avcodec.h"
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(...) av_log(NULL, AV_LOG_DEBUG, __VA_ARGS__)

#else //TRACE
#ifdef _MSC_VER //Picard
static inline void tprintf(const char* s,...) {}
#else
#define tprintf(...) {}
#endif
#endif

static inline int decode012(GetBitContext *gb){
    int n;
    n = get_bits1(gb);
    if (n == 0)
        return 0;
    else
        return get_bits1(gb) + 1;
}

#endif /* BITSTREAM_H */