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

 * 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;    \

    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) 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;

}

//#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 */