| /* |
| * 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 <stddef.h> |
| |
| #include "libavutil/intreadwrite.h" |
| #include "libavutil/avassert.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; |
| } |
| |
| /** |
| * Rebase the bit writer onto a reallocated buffer. |
| * |
| * @param buffer the buffer where to put bits |
| * @param buffer_size the size in bytes of buffer, |
| * must be larger than the previous size |
| */ |
| static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer, |
| int buffer_size) |
| { |
| av_assert0(8*buffer_size > s->size_in_bits); |
| |
| s->buf_end = buffer + buffer_size; |
| s->buf_ptr = buffer + (s->buf_ptr - s->buf); |
| s->buf = buffer; |
| s->size_in_bits = 8 * buffer_size; |
| } |
| |
| /** |
| * @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; |
| } |
| |
| /** |
| * @return the number of bits available in the bitstream. |
| */ |
| static inline int put_bits_left(PutBitContext* s) |
| { |
| return (s->buf_end - s->buf_ptr) * 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) { |
| av_assert0(s->buf_ptr < s->buf_end); |
| #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; |
| } |
| |
| static inline void flush_put_bits_le(PutBitContext *s) |
| { |
| while (s->bit_left < 32) { |
| av_assert0(s->buf_ptr < s->buf_end); |
| *s->buf_ptr++ = s->bit_buf; |
| s->bit_buf >>= 8; |
| 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) { |
| if (3 < s->buf_end - s->buf_ptr) { |
| AV_WL32(s->buf_ptr, bit_buf); |
| s->buf_ptr += 4; |
| } else { |
| av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); |
| av_assert2(0); |
| } |
| bit_buf = 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 (3 < s->buf_end - s->buf_ptr) { |
| AV_WB32(s->buf_ptr, bit_buf); |
| s->buf_ptr += 4; |
| } else { |
| av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); |
| av_assert2(0); |
| } |
| bit_left += 32 - n; |
| bit_buf = value; |
| } |
| #endif |
| |
| s->bit_buf = bit_buf; |
| s->bit_left = bit_left; |
| } |
| |
| static inline void put_bits_le(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; |
| |
| bit_buf |= value << (32 - bit_left); |
| if (n >= bit_left) { |
| if (3 < s->buf_end - s->buf_ptr) { |
| AV_WL32(s->buf_ptr, bit_buf); |
| s->buf_ptr += 4; |
| } else { |
| av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); |
| av_assert2(0); |
| } |
| bit_buf = value >> bit_left; |
| bit_left += 32; |
| } |
| bit_left -= n; |
| |
| 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, av_mod_uintp2(value, n)); |
| } |
| |
| /** |
| * Write exactly 32 bits into a bitstream. |
| */ |
| static void av_unused put_bits32(PutBitContext *s, uint32_t value) |
| { |
| unsigned int bit_buf; |
| int bit_left; |
| |
| bit_buf = s->bit_buf; |
| bit_left = s->bit_left; |
| |
| #ifdef BITSTREAM_WRITER_LE |
| bit_buf |= value << (32 - bit_left); |
| if (3 < s->buf_end - s->buf_ptr) { |
| AV_WL32(s->buf_ptr, bit_buf); |
| s->buf_ptr += 4; |
| } else { |
| av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); |
| av_assert2(0); |
| } |
| bit_buf = (uint64_t)value >> bit_left; |
| #else |
| bit_buf = (uint64_t)bit_buf << bit_left; |
| bit_buf |= value >> (32 - bit_left); |
| if (3 < s->buf_end - s->buf_ptr) { |
| AV_WB32(s->buf_ptr, bit_buf); |
| s->buf_ptr += 4; |
| } else { |
| av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); |
| av_assert2(0); |
| } |
| bit_buf = value; |
| #endif |
| |
| s->bit_buf = bit_buf; |
| s->bit_left = bit_left; |
| } |
| |
| /** |
| * Write up to 64 bits into a bitstream. |
| */ |
| static inline void put_bits64(PutBitContext *s, int n, uint64_t value) |
| { |
| av_assert2((n == 64) || (n < 64 && value < (UINT64_C(1) << n))); |
| |
| if (n < 32) |
| put_bits(s, n, value); |
| else if (n == 32) |
| put_bits32(s, value); |
| else if (n < 64) { |
| uint32_t lo = value & 0xffffffff; |
| uint32_t hi = value >> 32; |
| #ifdef BITSTREAM_WRITER_LE |
| put_bits32(s, lo); |
| put_bits(s, n - 32, hi); |
| #else |
| put_bits(s, n - 32, hi); |
| put_bits32(s, lo); |
| #endif |
| } else { |
| uint32_t lo = value & 0xffffffff; |
| uint32_t hi = value >> 32; |
| #ifdef BITSTREAM_WRITER_LE |
| put_bits32(s, lo); |
| put_bits32(s, hi); |
| #else |
| put_bits32(s, hi); |
| put_bits32(s, 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); |
| av_assert0(n <= s->buf_end - s->buf_ptr); |
| 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) |
| { |
| av_assert0(size <= INT_MAX/8 - 32); |
| s->buf_end = s->buf + size; |
| s->size_in_bits = 8*size; |
| } |
| |
| #endif /* AVCODEC_PUT_BITS_H */ |