On 07/05/16 06:07, Alexandra Hájková wrote:
> ---
> libavcodec/bitstream.h | 465
> +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 465 insertions(+)
> create mode 100644 libavcodec/bitstream.h
>
> diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h
> new file mode 100644
> index 0000000..0b16059
> --- /dev/null
> +++ b/libavcodec/bitstream.h
> @@ -0,0 +1,465 @@
> +/*
> + * 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
> + * bitstream reader API header.
> + */
> +
> +#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"
> +#include "vlc.h"
> +
> +typedef struct BitstreamContext {
> + uint64_t bits; // stores bits read from the buffer
> + const uint8_t *buffer, *buffer_end;
> + const uint8_t *ptr; // pointer to the position inside a buffer
> + unsigned bits_left; // number of bits left in bits field
> + unsigned size_in_bits;
> +} BitstreamContext;
> +
> +/**
> + * Return number of bits already read.
> + */
> +static inline int bitstream_tell(const BitstreamContext *s)
> +{
> + return (s->ptr - s->buffer) * 8 - s->bits_left;
> +}
> +
> +static inline void refill_64(BitstreamContext *s)
> +{
> + if (av_unlikely(s->ptr >= s->buffer_end || !s->buffer))
> + return;
> +
> +#ifdef BITSTREAM_READER_LE
> + s->bits = AV_RL64(s->ptr);
> +#else
> + s->bits = AV_RB64(s->ptr);
> +#endif
> + s->ptr += 8;
> + s->bits_left = 64;
> +}
> +
> +static inline uint64_t get_val(BitstreamContext *s, int n)
> +{
> + uint64_t ret;
> +
> +#ifdef BITSTREAM_READER_LE
> + ret = s->bits & ((UINT64_C(1) << n) - 1);
> + s->bits >>= n;
> +#else
> + ret = s->bits >> (64 - n);
> + s->bits <<= n;
> +#endif
> + s->bits_left -= n;
> +
> + return ret;
> +}
> +
> +/**
> + * Return one bit from the buffer.
> + */
> +static inline unsigned int bitstream_read_bit(BitstreamContext *s)
> +{
> + if (av_unlikely(!s->bits_left))
> + refill_64(s);
> +
> + return (uint8_t)get_val(s, 1);
I'd use !!get_val(s, 1)
The rest is sort of ok for me.
lu
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