vp9/encoder/vp9_write_bit_buffer.c

   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 #include <limits.h>
  12 #include "vp9/encoder/vp9_write_bit_buffer.h"
  13
  14 size_t vp9_wb_bytes_written(const struct vp9_write_bit_buffer *wb) {
  15   return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
  16 }
  17
  18 void vp9_wb_write_bit(struct vp9_write_bit_buffer *wb, int bit) {
  19   const int off = (int)wb->bit_offset;
  20   const int p = off / CHAR_BIT;
  21   const int q = CHAR_BIT - 1 - off % CHAR_BIT;
  22   if (q == CHAR_BIT -1) {
  23     wb->bit_buffer[p] = bit << q;
  24   } else {
  25     wb->bit_buffer[p] &= ~(1 << q);
  26     wb->bit_buffer[p] |= bit << q;
  27   }
  28   wb->bit_offset = off + 1;
  29 }
  30
  31 void vp9_wb_write_literal(struct vp9_write_bit_buffer *wb, int data, int bits) {
  32   int bit;
  33   for (bit = bits - 1; bit >= 0; bit--)
  34     vp9_wb_write_bit(wb, (data >> bit) & 1);
  35 }