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/put_bits.h

 * bitstream writer API

 */

#ifndef AVCODEC_PUT_BITS_H

#define AVCODEC_PUT_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"

//#define ALT_BITSTREAM_WRITER

//#define ALIGNED_BITSTREAM_WRITER

/* buf and buf_end must be present and used by every alternative writer. */

typedef struct PutBitContext {

#ifdef ALT_BITSTREAM_WRITER

    uint8_t *buf, *buf_end;

    int index;

#else

    uint32_t bit_buf;

    int bit_left;

    uint8_t *buf, *buf_ptr, *buf_end;

#endif

    int size_in_bits;

} PutBitContext;

/**

 * Initializes the PutBitContext \p s.

 *

 * @param buffer the buffer where to put bits

 * @param buffer_size the size in bytes of \p buffer

 */

static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)

{

    if(buffer_size < 0) {

        buffer_size = 0;

        buffer = NULL;

    }

    s->size_in_bits= 8*buffer_size;

    s->buf = buffer;

    s->buf_end = s->buf + buffer_size;

#ifdef ALT_BITSTREAM_WRITER

    s->index=0;

    ((uint32_t*)(s->buf))[0]=0;

//    memset(buffer, 0, buffer_size);

#else

    s->buf_ptr = s->buf;

    s->bit_left=32;

    s->bit_buf=0;

#endif

}

/**

 * Returns the total number of bits written to the bitstream.

 */

static inline int put_bits_count(PutBitContext *s)

{

#ifdef ALT_BITSTREAM_WRITER

    return s->index;

#else

    return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;

#endif

}

/**

 * Pads the end of the output stream with zeros.

 */

static inline void flush_put_bits(PutBitContext *s)

{

#ifdef ALT_BITSTREAM_WRITER

    align_put_bits(s);

#else

#ifndef BITSTREAM_WRITER_LE

    s->bit_buf<<= s->bit_left;

#endif

    while (s->bit_left < 32) {

        /* XXX: should test end of buffer */

#ifdef BITSTREAM_WRITER_LE

        *s->buf_ptr++=s->bit_buf;

        s->bit_buf>>=8;

#else

        *s->buf_ptr++=s->bit_buf >> 24;

        s->bit_buf<<=8;

#endif

        s->bit_left+=8;

    }

    s->bit_left=32;

    s->bit_buf=0;

#endif

}

/**

 * Pads the bitstream with zeros up to the next byte boundary.

 */

void align_put_bits(PutBitContext *s);

/**

 * Puts the string \p s in the bitstream.

 *

 * @param terminate_string 0-terminates the written string if value is 1

 */

void ff_put_string(PutBitContext * pbc, const char *s, int terminate_string);

/**

 * Copies the content of \p src to the bitstream.

 *

 * @param length the number of bits of \p src to copy

 */

void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);

static inline void put_bits(PutBitContext *s, int n, unsigned int value)

#ifndef ALT_BITSTREAM_WRITER

{

    unsigned int bit_buf;

    int bit_left;

    //    printf("put_bits=%d %x\n", n, value);

    assert(n == 32 || value < (1U << n));

    bit_buf = s->bit_buf;

    bit_left = s->bit_left;

    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);

    /* XXX: optimize */

#ifdef BITSTREAM_WRITER_LE

    bit_buf |= value << (32 - bit_left);

    if (n >= bit_left) {

#if !HAVE_FAST_UNALIGNED

        if (3 & (intptr_t) s->buf_ptr) {

            AV_WL32(s->buf_ptr, bit_buf);

        } else

#endif

        *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);

        s->buf_ptr+=4;

        bit_buf = (bit_left==32)?0:value >> bit_left;

        bit_left+=32;

    }

    bit_left-=n;

#else

    if (n < bit_left) {

        bit_buf = (bit_buf<<n) | value;

        bit_left-=n;

    } else {

        bit_buf<<=bit_left;

        bit_buf |= value >> (n - bit_left);

#if !HAVE_FAST_UNALIGNED

        if (3 & (intptr_t) s->buf_ptr) {

            AV_WB32(s->buf_ptr, bit_buf);

        } else

#endif

        *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);

        //printf("bitbuf = %08x\n", bit_buf);

        s->buf_ptr+=4;

        bit_left+=32 - n;

        bit_buf = value;

    }

#endif

    s->bit_buf = bit_buf;

    s->bit_left = bit_left;

}

#else  /* ALT_BITSTREAM_WRITER defined */

{

#    ifdef ALIGNED_BITSTREAM_WRITER

#        if ARCH_X86

    __asm__ volatile(

        "movl %0, %%ecx                 \n\t"

        "xorl %%eax, %%eax              \n\t"

        "shrdl %%cl, %1, %%eax          \n\t"

        "shrl %%cl, %1                  \n\t"

        "movl %0, %%ecx                 \n\t"

        "shrl $3, %%ecx                 \n\t"

        "andl $0xFFFFFFFC, %%ecx        \n\t"

        "bswapl %1                      \n\t"

        "orl %1, (%2, %%ecx)            \n\t"

        "bswapl %%eax                   \n\t"

        "addl %3, %0                    \n\t"

        "movl %%eax, 4(%2, %%ecx)       \n\t"

        : "=&r" (s->index), "=&r" (value)

        : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))

        : "%eax", "%ecx"

    );

#        else

    int index= s->index;

    uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);

    value<<= 32-n;

    ptr[0] |= be2me_32(value>>(index&31));

    ptr[1]  = be2me_32(value<<(32-(index&31)));

//if(n>24) printf("%d %d\n", n, value);

    index+= n;

    s->index= index;

#        endif

#    else //ALIGNED_BITSTREAM_WRITER

#        if ARCH_X86

    __asm__ volatile(

        "movl $7, %%ecx                 \n\t"

        "andl %0, %%ecx                 \n\t"

        "addl %3, %%ecx                 \n\t"

        "negl %%ecx                     \n\t"

        "shll %%cl, %1                  \n\t"

        "bswapl %1                      \n\t"

        "movl %0, %%ecx                 \n\t"

        "shrl $3, %%ecx                 \n\t"

        "orl %1, (%%ecx, %2)            \n\t"

        "addl %3, %0                    \n\t"

        "movl $0, 4(%%ecx, %2)          \n\t"

        : "=&r" (s->index), "=&r" (value)

        : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)

        : "%ecx"

    );

#        else

    int index= s->index;

    uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));

    ptr[0] |= be2me_32(value<<(32-n-(index&7) ));

    ptr[1] = 0;

//if(n>24) printf("%d %d\n", n, value);

    index+= n;

    s->index= index;

#        endif

#    endif //!ALIGNED_BITSTREAM_WRITER

}

#endif

static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)

{

    assert(bits >= 0 && bits <= 31);

    put_bits(pb, bits, val & ((1<<bits)-1));

}

static inline uint8_t* pbBufPtr(PutBitContext *s)

{

#ifdef ALT_BITSTREAM_WRITER

        return s->buf + (s->index>>3);

#else

        return s->buf_ptr;

#endif

}

/**

 * Skips the given number of bytes.

 * PutBitContext must be flushed & aligned to a byte boundary before calling this.

 */

static inline void skip_put_bytes(PutBitContext *s, int n){

        assert((put_bits_count(s)&7)==0);

#ifdef ALT_BITSTREAM_WRITER

        FIXME may need some cleaning of the buffer

        s->index += n<<3;

#else

        assert(s->bit_left==32);

        s->buf_ptr += n;

#endif

}

/**

 * Skips the given number of bits.

 * Must only be used if the actual values in the bitstream do not matter.

 * If \p n is 0 the behavior is undefined.

 */

static inline void skip_put_bits(PutBitContext *s, int n){

#ifdef ALT_BITSTREAM_WRITER

    s->index += n;

#else

    s->bit_left -= n;

    s->buf_ptr-= s->bit_left>>5;

    s->bit_left &= 31;

#endif

}

/**

 * Changes the end of the buffer.

 *

 * @param size the new size in bytes of the buffer where to put bits

 */

static inline void set_put_bits_buffer_size(PutBitContext *s, int size){

    s->buf_end= s->buf + size;

}

#endif /* AVCODEC_PUT_BITS_H */