vp9_write_bit_buffer.h revision 2ec72e65689c948e92b826ae1e867bf369e72f13 
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
11#ifndef VP9_ENCODER_VP9_WRITE_BIT_BUFFER_H_
12#define VP9_ENCODER_VP9_WRITE_BIT_BUFFER_H_
13
14#include <limits.h>
15
16#include "vpx/vpx_integer.h"
17
18#ifdef __cplusplus
19extern "C" {
20#endif
21
22struct vp9_write_bit_buffer {
23  uint8_t *bit_buffer;
24  size_t bit_offset;
25};
26
27static size_t vp9_rb_bytes_written(struct vp9_write_bit_buffer *wb) {
28  return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
29}
30
31static void vp9_wb_write_bit(struct vp9_write_bit_buffer *wb, int bit) {
32  const int off = (int)wb->bit_offset;
33  const int p = off / CHAR_BIT;
34  const int q = CHAR_BIT - 1 - off % CHAR_BIT;
35  if (q == CHAR_BIT -1) {
36    wb->bit_buffer[p] = bit << q;
37  } else {
38    wb->bit_buffer[p] &= ~(1 << q);
39    wb->bit_buffer[p] |= bit << q;
40  }
41  wb->bit_offset = off + 1;
42}
43
44static void vp9_wb_write_literal(struct vp9_write_bit_buffer *wb,
45                              int data, int bits) {
46  int bit;
47  for (bit = bits - 1; bit >= 0; bit--)
48    vp9_wb_write_bit(wb, (data >> bit) & 1);
49}
50
51
52#ifdef __cplusplus
53}  // extern "C"
54#endif
55
56#endif  // VP9_ENCODER_VP9_WRITE_BIT_BUFFER_H_
57