1/*
2 *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10#include "vp9/decoder/vp9_read_bit_buffer.h"
11
12size_t vp9_rb_bytes_read(struct vp9_read_bit_buffer *rb) {
13  return rb->bit_offset / CHAR_BIT + (rb->bit_offset % CHAR_BIT > 0);
14}
15
16int vp9_rb_read_bit(struct vp9_read_bit_buffer *rb) {
17  const size_t off = rb->bit_offset;
18  const size_t p = off / CHAR_BIT;
19  const int q = CHAR_BIT - 1 - (int)off % CHAR_BIT;
20  if (rb->bit_buffer + p >= rb->bit_buffer_end) {
21    rb->error_handler(rb->error_handler_data);
22    return 0;
23  } else {
24    const int bit = (rb->bit_buffer[p] & (1 << q)) >> q;
25    rb->bit_offset = off + 1;
26    return bit;
27  }
28}
29
30int vp9_rb_read_literal(struct vp9_read_bit_buffer *rb, int bits) {
31  int value = 0, bit;
32  for (bit = bits - 1; bit >= 0; bit--)
33    value |= vp9_rb_read_bit(rb) << bit;
34  return value;
35}
36
37int vp9_rb_read_signed_literal(struct vp9_read_bit_buffer *rb,
38                               int bits) {
39  const int value = vp9_rb_read_literal(rb, bits);
40  return vp9_rb_read_bit(rb) ? -value : value;
41}
42