/* * 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 "config.h" #include "libavutil/intreadwrite.h" #include "libavutil/avassert.h" #include "libavutil/common.h" #if ARCH_X86_64 // TODO: Benchmark and optionally enable on other 64-bit architectures. typedef uint64_t BitBuf; #define AV_WBBUF AV_WB64 #define AV_WLBUF AV_WL64 #else typedef uint32_t BitBuf; #define AV_WBBUF AV_WB32 #define AV_WLBUF AV_WL32 #endif static const int BUF_BITS = 8 * sizeof(BitBuf); typedef struct PutBitContext { BitBuf bit_buf; int bit_left; uint8_t *buf, *buf_ptr, *buf_end; } 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->buf = buffer; s->buf_end = s->buf + buffer_size; s->buf_ptr = s->buf; s->bit_left = BUF_BITS; 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 + BUF_BITS - s->bit_left; } /** * @return the number of bytes output so far; may only be called * when the PutBitContext is freshly initialized or flushed. */ static inline int put_bytes_output(const PutBitContext *s) { av_assert2(s->bit_left == BUF_BITS); return s->buf_ptr - s->buf; } /** * @param round_up When set, the number of bits written so far will be * rounded up to the next byte. * @return the number of bytes output so far. */ static inline int put_bytes_count(const PutBitContext *s, int round_up) { return s->buf_ptr - s->buf + ((BUF_BITS - s->bit_left + (round_up ? 7 : 0)) >> 3); } /** * 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 large enough to hold everything written so far */ static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size) { av_assert0(8*buffer_size >= put_bits_count(s)); s->buf_end = buffer + buffer_size; s->buf_ptr = buffer + (s->buf_ptr - s->buf); s->buf = buffer; } /** * @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 - BUF_BITS + s->bit_left; } /** * @param round_up When set, the number of bits written will be * rounded up to the next byte. * @return the number of bytes left. */ static inline int put_bytes_left(const PutBitContext *s, int round_up) { return s->buf_end - s->buf_ptr - ((BUF_BITS - s->bit_left + (round_up ? 7 : 0)) >> 3); } /** * 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 < BUF_BITS) s->bit_buf <<= s->bit_left; #endif while (s->bit_left < BUF_BITS) { 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 >> (BUF_BITS - 8); s->bit_buf <<= 8; #endif s->bit_left += 8; } s->bit_left = BUF_BITS; s->bit_buf = 0; } static inline void flush_put_bits_le(PutBitContext *s) { while (s->bit_left < BUF_BITS) { 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 = BUF_BITS; s->bit_buf = 0; } #ifdef BITSTREAM_WRITER_LE #define ff_put_string ff_put_string_unsupported_here #define ff_copy_bits ff_copy_bits_unsupported_here #else /** * Put the string string in the bitstream. * * @param terminate_string 0-terminates the written string if value is 1 */ void ff_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 ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length); #endif static inline void put_bits_no_assert(PutBitContext *s, int n, BitBuf value) { BitBuf bit_buf; int bit_left; bit_buf = s->bit_buf; bit_left = s->bit_left; /* XXX: optimize */ #ifdef BITSTREAM_WRITER_LE bit_buf |= value << (BUF_BITS - bit_left); if (n >= bit_left) { if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) { AV_WLBUF(s->buf_ptr, bit_buf); s->buf_ptr += sizeof(BitBuf); } 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 += BUF_BITS; } 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 (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) { AV_WBBUF(s->buf_ptr, bit_buf); s->buf_ptr += sizeof(BitBuf); } else { av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n"); av_assert2(0); } bit_left += BUF_BITS - n; bit_buf = value; } #endif s->bit_buf = bit_buf; s->bit_left = bit_left; } /** * Write up to 31 bits into a bitstream. * Use put_bits32 to write 32 bits. */ static inline void put_bits(PutBitContext *s, int n, BitBuf value) { av_assert2(n <= 31 && value < (1UL << n)); put_bits_no_assert(s, n, value); } static inline void put_bits_le(PutBitContext *s, int n, BitBuf value) { BitBuf bit_buf; int bit_left; av_assert2(n <= 31 && value < (1UL << n)); bit_buf = s->bit_buf; bit_left = s->bit_left; bit_buf |= value << (BUF_BITS - bit_left); if (n >= bit_left) { if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) { AV_WLBUF(s->buf_ptr, bit_buf); s->buf_ptr += sizeof(BitBuf); } 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 += BUF_BITS; } 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) { BitBuf bit_buf; int bit_left; if (BUF_BITS > 32) { put_bits_no_assert(s, 32, value); return; } bit_buf = s->bit_buf; bit_left = s->bit_left; #ifdef BITSTREAM_WRITER_LE bit_buf |= (BitBuf)value << (BUF_BITS - bit_left); if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) { AV_WLBUF(s->buf_ptr, bit_buf); s->buf_ptr += sizeof(BitBuf); } 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 |= (BitBuf)value >> (BUF_BITS - bit_left); if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) { AV_WBBUF(s->buf_ptr, bit_buf); s->buf_ptr += sizeof(BitBuf); } 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 == BUF_BITS); 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) { unsigned bits = BUF_BITS - s->bit_left + n; s->buf_ptr += sizeof(BitBuf) * (bits / BUF_BITS); s->bit_left = BUF_BITS - (bits & (BUF_BITS - 1)); } /** * 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 - BUF_BITS); s->buf_end = s->buf + size; } /** * Pad the bitstream with zeros up to the next byte boundary. */ static inline void align_put_bits(PutBitContext *s) { put_bits(s, s->bit_left & 7, 0); } #undef AV_WBBUF #undef AV_WLBUF #endif /* AVCODEC_PUT_BITS_H */