yading@10: /*
yading@10:  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * bitstream writer API
yading@10:  */
yading@10: 
yading@10: #ifndef AVCODEC_PUT_BITS_H
yading@10: #define AVCODEC_PUT_BITS_H
yading@10: 
yading@10: #include <stdint.h>
yading@10: #include <stdlib.h>
yading@10: #include <assert.h>
yading@10: 
yading@10: #include "libavutil/bswap.h"
yading@10: #include "libavutil/common.h"
yading@10: #include "libavutil/intreadwrite.h"
yading@10: #include "libavutil/log.h"
yading@10: #include "libavutil/avassert.h"
yading@10: #include "mathops.h"
yading@10: #include "config.h"
yading@10: 
yading@10: typedef struct PutBitContext {
yading@10:     uint32_t bit_buf;
yading@10:     int bit_left;
yading@10:     uint8_t *buf, *buf_ptr, *buf_end;
yading@10:     int size_in_bits;
yading@10: } PutBitContext;
yading@10: 
yading@10: /**
yading@10:  * Initialize the PutBitContext s.
yading@10:  *
yading@10:  * @param buffer the buffer where to put bits
yading@10:  * @param buffer_size the size in bytes of buffer
yading@10:  */
yading@10: static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
yading@10:                                  int buffer_size)
yading@10: {
yading@10:     if (buffer_size < 0) {
yading@10:         buffer_size = 0;
yading@10:         buffer      = NULL;
yading@10:     }
yading@10: 
yading@10:     s->size_in_bits = 8 * buffer_size;
yading@10:     s->buf          = buffer;
yading@10:     s->buf_end      = s->buf + buffer_size;
yading@10:     s->buf_ptr      = s->buf;
yading@10:     s->bit_left     = 32;
yading@10:     s->bit_buf      = 0;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * @return the total number of bits written to the bitstream.
yading@10:  */
yading@10: static inline int put_bits_count(PutBitContext *s)
yading@10: {
yading@10:     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Pad the end of the output stream with zeros.
yading@10:  */
yading@10: static inline void flush_put_bits(PutBitContext *s)
yading@10: {
yading@10: #ifndef BITSTREAM_WRITER_LE
yading@10:     if (s->bit_left < 32)
yading@10:         s->bit_buf <<= s->bit_left;
yading@10: #endif
yading@10:     while (s->bit_left < 32) {
yading@10:         /* XXX: should test end of buffer */
yading@10: #ifdef BITSTREAM_WRITER_LE
yading@10:         *s->buf_ptr++ = s->bit_buf;
yading@10:         s->bit_buf  >>= 8;
yading@10: #else
yading@10:         *s->buf_ptr++ = s->bit_buf >> 24;
yading@10:         s->bit_buf  <<= 8;
yading@10: #endif
yading@10:         s->bit_left  += 8;
yading@10:     }
yading@10:     s->bit_left = 32;
yading@10:     s->bit_buf  = 0;
yading@10: }
yading@10: 
yading@10: #ifdef BITSTREAM_WRITER_LE
yading@10: #define avpriv_align_put_bits align_put_bits_unsupported_here
yading@10: #define avpriv_put_string ff_put_string_unsupported_here
yading@10: #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
yading@10: #else
yading@10: /**
yading@10:  * Pad the bitstream with zeros up to the next byte boundary.
yading@10:  */
yading@10: void avpriv_align_put_bits(PutBitContext *s);
yading@10: 
yading@10: /**
yading@10:  * Put the string string in the bitstream.
yading@10:  *
yading@10:  * @param terminate_string 0-terminates the written string if value is 1
yading@10:  */
yading@10: void avpriv_put_string(PutBitContext *pb, const char *string,
yading@10:                        int terminate_string);
yading@10: 
yading@10: /**
yading@10:  * Copy the content of src to the bitstream.
yading@10:  *
yading@10:  * @param length the number of bits of src to copy
yading@10:  */
yading@10: void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
yading@10: #endif
yading@10: 
yading@10: /**
yading@10:  * Write up to 31 bits into a bitstream.
yading@10:  * Use put_bits32 to write 32 bits.
yading@10:  */
yading@10: static inline void put_bits(PutBitContext *s, int n, unsigned int value)
yading@10: {
yading@10:     unsigned int bit_buf;
yading@10:     int bit_left;
yading@10: 
yading@10:     av_assert2(n <= 31 && value < (1U << n));
yading@10: 
yading@10:     bit_buf  = s->bit_buf;
yading@10:     bit_left = s->bit_left;
yading@10: 
yading@10:     /* XXX: optimize */
yading@10: #ifdef BITSTREAM_WRITER_LE
yading@10:     bit_buf |= value << (32 - bit_left);
yading@10:     if (n >= bit_left) {
yading@10:         av_assert2(s->buf_ptr+3<s->buf_end);
yading@10:         AV_WL32(s->buf_ptr, bit_buf);
yading@10:         s->buf_ptr += 4;
yading@10:         bit_buf     = (bit_left == 32) ? 0 : value >> bit_left;
yading@10:         bit_left   += 32;
yading@10:     }
yading@10:     bit_left -= n;
yading@10: #else
yading@10:     if (n < bit_left) {
yading@10:         bit_buf     = (bit_buf << n) | value;
yading@10:         bit_left   -= n;
yading@10:     } else {
yading@10:         bit_buf   <<= bit_left;
yading@10:         bit_buf    |= value >> (n - bit_left);
yading@10:         av_assert2(s->buf_ptr+3<s->buf_end);
yading@10:         AV_WB32(s->buf_ptr, bit_buf);
yading@10:         s->buf_ptr += 4;
yading@10:         bit_left   += 32 - n;
yading@10:         bit_buf     = value;
yading@10:     }
yading@10: #endif
yading@10: 
yading@10:     s->bit_buf  = bit_buf;
yading@10:     s->bit_left = bit_left;
yading@10: }
yading@10: 
yading@10: static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
yading@10: {
yading@10:     av_assert2(n >= 0 && n <= 31);
yading@10: 
yading@10:     put_bits(pb, n, value & ((1 << n) - 1));
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Write exactly 32 bits into a bitstream.
yading@10:  */
yading@10: static void av_unused put_bits32(PutBitContext *s, uint32_t value)
yading@10: {
yading@10:     int lo = value & 0xffff;
yading@10:     int hi = value >> 16;
yading@10: #ifdef BITSTREAM_WRITER_LE
yading@10:     put_bits(s, 16, lo);
yading@10:     put_bits(s, 16, hi);
yading@10: #else
yading@10:     put_bits(s, 16, hi);
yading@10:     put_bits(s, 16, lo);
yading@10: #endif
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Return the pointer to the byte where the bitstream writer will put
yading@10:  * the next bit.
yading@10:  */
yading@10: static inline uint8_t *put_bits_ptr(PutBitContext *s)
yading@10: {
yading@10:     return s->buf_ptr;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Skip the given number of bytes.
yading@10:  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
yading@10:  */
yading@10: static inline void skip_put_bytes(PutBitContext *s, int n)
yading@10: {
yading@10:     av_assert2((put_bits_count(s) & 7) == 0);
yading@10:     av_assert2(s->bit_left == 32);
yading@10:     s->buf_ptr += n;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Skip the given number of bits.
yading@10:  * Must only be used if the actual values in the bitstream do not matter.
yading@10:  * If n is 0 the behavior is undefined.
yading@10:  */
yading@10: static inline void skip_put_bits(PutBitContext *s, int n)
yading@10: {
yading@10:     s->bit_left -= n;
yading@10:     s->buf_ptr  -= 4 * (s->bit_left >> 5);
yading@10:     s->bit_left &= 31;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Change the end of the buffer.
yading@10:  *
yading@10:  * @param size the new size in bytes of the buffer where to put bits
yading@10:  */
yading@10: static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
yading@10: {
yading@10:     s->buf_end = s->buf + size;
yading@10: }
yading@10: 
yading@10: #endif /* AVCODEC_PUT_BITS_H */