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Diffstat (limited to 'libavcodec/bitstream.h')
-rw-r--r-- | libavcodec/bitstream.h | 344 |
1 files changed, 0 insertions, 344 deletions
diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h deleted file mode 100644 index 1b23cb2..0000000 --- a/libavcodec/bitstream.h +++ /dev/null @@ -1,344 +0,0 @@ -/* - * Copyright (c) 2016 Alexandra Hájková - * - * This file is part of Libav. - * - * Libav 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. - * - * Libav 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 Libav; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - */ - -/** - * @file - * functions for reading bits from a buffer - */ - -#ifndef AVCODEC_BITSTREAM_H -#define AVCODEC_BITSTREAM_H - -#include <stdint.h> - -#include "libavutil/common.h" -#include "libavutil/intreadwrite.h" -#include "libavutil/log.h" - -#include "mathops.h" - -typedef struct BitstreamContext { - uint64_t bits; // stores bits read from the buffer - const uint8_t *buffer, *buffer_end; - const uint8_t *ptr; // position inside a buffer - unsigned bits_left; // number of bits left in bits field - unsigned size_in_bits; -} BitstreamContext; - -static inline void refill_64(BitstreamContext *bc) -{ - if (bc->ptr >= bc->buffer_end) - return; - -#ifdef BITSTREAM_READER_LE - bc->bits = AV_RL64(bc->ptr); -#else - bc->bits = AV_RB64(bc->ptr); -#endif - bc->ptr += 8; - bc->bits_left = 64; -} - -static inline void refill_32(BitstreamContext *bc) -{ - if (bc->ptr >= bc->buffer_end) - return; - -#ifdef BITSTREAM_READER_LE - bc->bits = (uint64_t)AV_RL32(bc->ptr) << bc->bits_left | bc->bits; -#else - bc->bits = bc->bits | (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_left); -#endif - bc->ptr += 4; - bc->bits_left += 32; -} - -/* Initialize BitstreamContext. Input buffer must have an additional zero - * padding of AV_INPUT_BUFFER_PADDING_SIZE bytes at the end. */ -static inline int bitstream_init(BitstreamContext *bc, const uint8_t *buffer, - unsigned bit_size) -{ - unsigned buffer_size; - - if (bit_size > INT_MAX - 7 || !buffer) { - buffer = - bc->buffer = - bc->ptr = NULL; - bc->bits_left = 0; - return AVERROR_INVALIDDATA; - } - - buffer_size = (bit_size + 7) >> 3; - - bc->buffer = buffer; - bc->buffer_end = buffer + buffer_size; - bc->ptr = bc->buffer; - bc->size_in_bits = bit_size; - bc->bits_left = 0; - bc->bits = 0; - - refill_64(bc); - - return 0; -} - -/* Initialize BitstreamContext with buffer size in bytes instead of bits. */ -static inline int bitstream_init8(BitstreamContext *bc, const uint8_t *buffer, - unsigned byte_size) -{ - if (byte_size > INT_MAX / 8) - return AVERROR_INVALIDDATA; - return bitstream_init(bc, buffer, byte_size * 8); -} - -/* Return number of bits already read. */ -static inline int bitstream_tell(const BitstreamContext *bc) -{ - return (bc->ptr - bc->buffer) * 8 - bc->bits_left; -} - -/* Return buffer size in bits. */ -static inline int bitstream_tell_size(const BitstreamContext *bc) -{ - return bc->size_in_bits; -} - -/* Return the number of the bits left in a buffer. */ -static inline int bitstream_bits_left(const BitstreamContext *bc) -{ - return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_left; -} - -static inline uint64_t get_val(BitstreamContext *bc, unsigned n) -{ -#ifdef BITSTREAM_READER_LE - uint64_t ret = bc->bits & ((UINT64_C(1) << n) - 1); - bc->bits >>= n; -#else - uint64_t ret = bc->bits >> (64 - n); - bc->bits <<= n; -#endif - bc->bits_left -= n; - - return ret; -} - -/* Return one bit from the buffer. */ -static inline unsigned bitstream_read_bit(BitstreamContext *bc) -{ - if (!bc->bits_left) - refill_64(bc); - - return get_val(bc, 1); -} - -/* Return n bits from the buffer. n has to be in the 0-63 range. */ -static inline uint64_t bitstream_read_63(BitstreamContext *bc, unsigned n) -{ - uint64_t ret = 0; -#ifdef BITSTREAM_READER_LE - uint64_t left = 0; -#endif - - if (!n) - return 0; - - if (n > bc->bits_left) { - n -= bc->bits_left; -#ifdef BITSTREAM_READER_LE - left = bc->bits_left; -#endif - ret = get_val(bc, bc->bits_left); - refill_64(bc); - } - -#ifdef BITSTREAM_READER_LE - ret = get_val(bc, n) << left | ret; -#else - ret = get_val(bc, n) | ret << n; -#endif - - return ret; -} - -/* Return n bits from the buffer. n has to be in the 0-32 range. */ -static inline uint32_t bitstream_read(BitstreamContext *bc, unsigned n) -{ - if (!n) - return 0; - - if (n > bc->bits_left) { - refill_32(bc); - if (bc->bits_left < 32) - bc->bits_left = n; - } - - return get_val(bc, n); -} - -/* Return n bits from the buffer as a signed integer. - * n has to be in the 0-32 range. */ -static inline int32_t bitstream_read_signed(BitstreamContext *bc, unsigned n) -{ - return sign_extend(bitstream_read(bc, n), n); -} - -static inline unsigned show_val(const BitstreamContext *bc, unsigned n) -{ -#ifdef BITSTREAM_READER_LE - return bc->bits & ((UINT64_C(1) << n) - 1); -#else - return bc->bits >> (64 - n); -#endif -} - -/* Return n bits from the buffer, but do not change the buffer state. - * n has to be in the 0-32 range. */ -static inline unsigned bitstream_peek(BitstreamContext *bc, unsigned n) -{ - if (n > bc->bits_left) - refill_32(bc); - - return show_val(bc, n); -} - -/* Return n bits from the buffer as a signed integer, but do not change the - * buffer state. n has to be in the 0-32 range. */ -static inline int bitstream_peek_signed(BitstreamContext *bc, unsigned n) -{ - return sign_extend(bitstream_peek(bc, n), n); -} - -static inline void skip_remaining(BitstreamContext *bc, unsigned n) -{ -#ifdef BITSTREAM_READER_LE - bc->bits >>= n; -#else - bc->bits <<= n; -#endif - bc->bits_left -= n; -} - -/* Skip n bits in the buffer. */ -static inline void bitstream_skip(BitstreamContext *bc, unsigned n) -{ - if (n < bc->bits_left) - skip_remaining(bc, n); - else { - n -= bc->bits_left; - bc->bits = 0; - bc->bits_left = 0; - - if (n >= 64) { - unsigned skip = n / 8; - - n -= skip * 8; - bc->ptr += skip; - } - refill_64(bc); - if (n) - skip_remaining(bc, n); - } -} - -/* Seek to the given bit position. */ -static inline void bitstream_seek(BitstreamContext *bc, unsigned pos) -{ - bc->ptr = bc->buffer; - bc->bits = 0; - bc->bits_left = 0; - - bitstream_skip(bc, pos); -} - -/* Skip bits to a byte boundary. */ -static inline const uint8_t *bitstream_align(BitstreamContext *bc) -{ - unsigned n = -bitstream_tell(bc) & 7; - if (n) - bitstream_skip(bc, n); - return bc->buffer + (bitstream_tell(bc) >> 3); -} - -/* Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). - * If MSB not set it is negative. */ -static inline int bitstream_read_xbits(BitstreamContext *bc, unsigned length) -{ - int32_t cache = bitstream_peek(bc, 32); - int sign = ~cache >> 31; - skip_remaining(bc, length); - - return ((((uint32_t)(sign ^ cache)) >> (32 - length)) ^ sign) - sign; -} - -/* Return decoded truncated unary code for the values 0, 1, 2. */ -static inline int bitstream_decode012(BitstreamContext *bc) -{ - if (!bitstream_read_bit(bc)) - return 0; - else - return bitstream_read_bit(bc) + 1; -} - -/* Return decoded truncated unary code for the values 2, 1, 0. */ -static inline int bitstream_decode210(BitstreamContext *bc) -{ - if (bitstream_read_bit(bc)) - return 0; - else - return 2 - bitstream_read_bit(bc); -} - -/* Read sign bit and flip the sign of the provided value accordingly. */ -static inline int bitstream_apply_sign(BitstreamContext *bc, int val) -{ - int sign = bitstream_read_signed(bc, 1); - return (val ^ sign) - sign; -} - -/* Unwind the cache so a refill_32 can fill it again. */ -static inline void bitstream_unwind(BitstreamContext *bc) -{ - int unwind = 4; - int unwind_bits = unwind * 8; - - if (bc->bits_left < unwind_bits) - return; - - bc->bits >>= unwind_bits; - bc->bits <<= unwind_bits; - bc->bits_left -= unwind_bits; - bc->ptr -= unwind; -} - -/* Unget up to 32 bits. */ -static inline void bitstream_unget(BitstreamContext *bc, uint64_t value, - size_t amount) -{ - size_t cache_size = sizeof(bc->bits) * 8; - - if (bc->bits_left + amount > cache_size) - bitstream_unwind(bc); - - bc->bits = (bc->bits >> amount) | (value << (cache_size - amount)); - bc->bits_left += amount; -} - -#endif /* AVCODEC_BITSTREAM_H */ |