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_BIT_WRITE_BUFFER_H_ 12 #define VP9_BIT_WRITE_BUFFER_H_ 13 14 #include <limits.h> 15 16 #include "vpx/vpx_integer.h" 17 18 struct vp9_write_bit_buffer { 19 uint8_t *bit_buffer; 20 size_t bit_offset; 21 }; 22 23 static size_t vp9_rb_bytes_written(struct vp9_write_bit_buffer *wb) { 24 return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0); 25 } 26 27 static void vp9_wb_write_bit(struct vp9_write_bit_buffer *wb, int bit) { 28 const int off = wb->bit_offset; 29 const int p = off / CHAR_BIT; 30 const int q = CHAR_BIT - 1 - off % CHAR_BIT; 31 if (q == CHAR_BIT -1) { 32 wb->bit_buffer[p] = bit << q; 33 } else { 34 wb->bit_buffer[p] &= ~(1 << q); 35 wb->bit_buffer[p] |= bit << q; 36 } 37 wb->bit_offset = off + 1; 38 } 39 40 static void vp9_wb_write_literal(struct vp9_write_bit_buffer *wb, 41 int data, int bits) { 42 int bit; 43 for (bit = bits - 1; bit >= 0; bit--) 44 vp9_wb_write_bit(wb, (data >> bit) & 1); 45 } 46 47 48 #endif // VP9_BIT_WRITE_BUFFER_H_ 49
