1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libvpx/vp9/decoder/vp9_read_bit_buffer.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,60 @@
1.4 +/*
1.5 + * Copyright (c) 2013 The WebM project authors. All Rights Reserved.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license
1.8 + * that can be found in the LICENSE file in the root of the source
1.9 + * tree. An additional intellectual property rights grant can be found
1.10 + * in the file PATENTS. All contributing project authors may
1.11 + * be found in the AUTHORS file in the root of the source tree.
1.12 + */
1.13 +
1.14 +#ifndef VP9_DECODER_VP9_READ_BIT_BUFFER_H_
1.15 +#define VP9_DECODER_VP9_READ_BIT_BUFFER_H_
1.16 +
1.17 +#include <limits.h>
1.18 +
1.19 +#include "vpx/vpx_integer.h"
1.20 +
1.21 +typedef void (*vp9_rb_error_handler)(void *data, size_t bit_offset);
1.22 +
1.23 +struct vp9_read_bit_buffer {
1.24 + const uint8_t *bit_buffer;
1.25 + const uint8_t *bit_buffer_end;
1.26 + size_t bit_offset;
1.27 +
1.28 + void *error_handler_data;
1.29 + vp9_rb_error_handler error_handler;
1.30 +};
1.31 +
1.32 +static size_t vp9_rb_bytes_read(struct vp9_read_bit_buffer *rb) {
1.33 + return rb->bit_offset / CHAR_BIT + (rb->bit_offset % CHAR_BIT > 0);
1.34 +}
1.35 +
1.36 +static int vp9_rb_read_bit(struct vp9_read_bit_buffer *rb) {
1.37 + const size_t off = rb->bit_offset;
1.38 + const size_t p = off / CHAR_BIT;
1.39 + const int q = CHAR_BIT - 1 - (int)off % CHAR_BIT;
1.40 + if (rb->bit_buffer + p >= rb->bit_buffer_end) {
1.41 + rb->error_handler(rb->error_handler_data, rb->bit_offset);
1.42 + return 0;
1.43 + } else {
1.44 + const int bit = (rb->bit_buffer[p] & (1 << q)) >> q;
1.45 + rb->bit_offset = off + 1;
1.46 + return bit;
1.47 + }
1.48 +}
1.49 +
1.50 +static int vp9_rb_read_literal(struct vp9_read_bit_buffer *rb, int bits) {
1.51 + int value = 0, bit;
1.52 + for (bit = bits - 1; bit >= 0; bit--)
1.53 + value |= vp9_rb_read_bit(rb) << bit;
1.54 + return value;
1.55 +}
1.56 +
1.57 +static int vp9_rb_read_signed_literal(struct vp9_read_bit_buffer *rb,
1.58 + int bits) {
1.59 + const int value = vp9_rb_read_literal(rb, bits);
1.60 + return vp9_rb_read_bit(rb) ? -value : value;
1.61 +}
1.62 +
1.63 +#endif // VP9_DECODER_VP9_READ_BIT_BUFFER_H_
