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Diffstat (limited to 'ffmpeg/libavcodec/put_bits.h')
| -rw-r--r-- | ffmpeg/libavcodec/put_bits.h | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/ffmpeg/libavcodec/put_bits.h b/ffmpeg/libavcodec/put_bits.h new file mode 100644 index 0000000..7320443 --- /dev/null +++ b/ffmpeg/libavcodec/put_bits.h @@ -0,0 +1,237 @@ +/* + * 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 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 "libavutil/avassert.h" +#include "mathops.h" +#include "config.h" + +typedef struct PutBitContext { + uint32_t bit_buf; + int bit_left; + uint8_t *buf, *buf_ptr, *buf_end; + int size_in_bits; +} PutBitContext; + +/** + * Initialize the PutBitContext s. + * + * @param buffer the buffer where to put bits + * @param buffer_size the size in bytes of 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; + s->buf_ptr = s->buf; + s->bit_left = 32; + s->bit_buf = 0; +} + +/** + * @return the total number of bits written to the bitstream. + */ +static inline int put_bits_count(PutBitContext *s) +{ + return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left; +} + +/** + * Pad the end of the output stream with zeros. + */ +static inline void flush_put_bits(PutBitContext *s) +{ +#ifndef BITSTREAM_WRITER_LE + if (s->bit_left < 32) + 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; +} + +#ifdef BITSTREAM_WRITER_LE +#define avpriv_align_put_bits align_put_bits_unsupported_here +#define avpriv_put_string ff_put_string_unsupported_here +#define avpriv_copy_bits avpriv_copy_bits_unsupported_here +#else +/** + * Pad the bitstream with zeros up to the next byte boundary. + */ +void avpriv_align_put_bits(PutBitContext *s); + +/** + * Put the string string in the bitstream. + * + * @param terminate_string 0-terminates the written string if value is 1 + */ +void avpriv_put_string(PutBitContext *pb, const char *string, + int terminate_string); + +/** + * Copy the content of src to the bitstream. + * + * @param length the number of bits of src to copy + */ +void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length); +#endif + +/** + * Write up to 31 bits into a bitstream. + * Use put_bits32 to write 32 bits. + */ +static inline void put_bits(PutBitContext *s, int n, unsigned int value) +{ + unsigned int bit_buf; + int bit_left; + + av_assert2(n <= 31 && value < (1U << n)); + + bit_buf = s->bit_buf; + bit_left = s->bit_left; + + /* XXX: optimize */ +#ifdef BITSTREAM_WRITER_LE + bit_buf |= value << (32 - bit_left); + if (n >= bit_left) { + av_assert2(s->buf_ptr+3<s->buf_end); + AV_WL32(s->buf_ptr, 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); + av_assert2(s->buf_ptr+3<s->buf_end); + AV_WB32(s->buf_ptr, bit_buf); + s->buf_ptr += 4; + bit_left += 32 - n; + bit_buf = value; + } +#endif + + s->bit_buf = bit_buf; + s->bit_left = bit_left; +} + +static inline void put_sbits(PutBitContext *pb, int n, int32_t value) +{ + av_assert2(n >= 0 && n <= 31); + + put_bits(pb, n, value & ((1 << n) - 1)); +} + +/** + * Write exactly 32 bits into a bitstream. + */ +static void av_unused put_bits32(PutBitContext *s, uint32_t value) +{ + int lo = value & 0xffff; + int hi = value >> 16; +#ifdef BITSTREAM_WRITER_LE + put_bits(s, 16, lo); + put_bits(s, 16, hi); +#else + put_bits(s, 16, hi); + put_bits(s, 16, lo); +#endif +} + +/** + * Return the pointer to the byte where the bitstream writer will put + * the next bit. + */ +static inline uint8_t *put_bits_ptr(PutBitContext *s) +{ + return s->buf_ptr; +} + +/** + * Skip 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) +{ + av_assert2((put_bits_count(s) & 7) == 0); + av_assert2(s->bit_left == 32); + s->buf_ptr += n; +} + +/** + * Skip the given number of bits. + * Must only be used if the actual values in the bitstream do not matter. + * If n is 0 the behavior is undefined. + */ +static inline void skip_put_bits(PutBitContext *s, int n) +{ + s->bit_left -= n; + s->buf_ptr -= 4 * (s->bit_left >> 5); + s->bit_left &= 31; +} + +/** + * Change 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 */ |