PeerStreamer

/*

 * 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 libavcodec/get_bits.h

 * 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

#       define A32_BITSTREAM_READER

#   else

#       define ALT_BITSTREAM_READER

//#define LIBMPEG2_BITSTREAM_READER

//#define A32_BITSTREAM_READER

#   endif

#endif

extern const uint8_t ff_reverse[256];

#if ARCH_X86

// avoid +32 for shift optimization (gcc should do that ...)

static inline  int32_t NEG_SSR32( int32_t a, int8_t s){

    __asm__ ("sarl %1, %0\n\t"

         : "+r" (a)

         : "ic" ((uint8_t)(-s))

    );

    return a;

}

static inline uint32_t NEG_USR32(uint32_t a, int8_t s){

    __asm__ ("shrl %1, %0\n\t"

         : "+r" (a)

         : "ic" ((uint8_t)(-s))

    );

    return a;

}

#else

#    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))

#    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))

#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 SKIP_LAST_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)\

        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)\

        ((name##_cache) & (NEG_USR32(0xffffffff,num)))

#   define SHOW_SBITS(name, gb, num)\

        NEG_SSR32((name##_cache)<<(32-(num)), 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(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(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= 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 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(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 = be2me_32( 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

    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<=17) 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<=17) 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

 */

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_USE_STATIC 1 ///< VERY strongly deprecated and forbidden

#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 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)\

}

/**

 * 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);

}

#endif /* AVCODEC_GET_BITS_H */