michael@0: /*
michael@0:  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
michael@0:  *
michael@0:  *  Use of this source code is governed by a BSD-style license
michael@0:  *  that can be found in the LICENSE file in the root of the source
michael@0:  *  tree. An additional intellectual property rights grant can be found
michael@0:  *  in the file PATENTS.  All contributing project authors may
michael@0:  *  be found in the AUTHORS file in the root of the source tree.
michael@0:  */
michael@0: 
michael@0: #ifndef VP9_BIT_WRITE_BUFFER_H_
michael@0: #define VP9_BIT_WRITE_BUFFER_H_
michael@0: 
michael@0: #include <limits.h>
michael@0: 
michael@0: #include "vpx/vpx_integer.h"
michael@0: 
michael@0: struct vp9_write_bit_buffer {
michael@0:   uint8_t *bit_buffer;
michael@0:   size_t bit_offset;
michael@0: };
michael@0: 
michael@0: static size_t vp9_rb_bytes_written(struct vp9_write_bit_buffer *wb) {
michael@0:   return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
michael@0: }
michael@0: 
michael@0: static void vp9_wb_write_bit(struct vp9_write_bit_buffer *wb, int bit) {
michael@0:   const int off = wb->bit_offset;
michael@0:   const int p = off / CHAR_BIT;
michael@0:   const int q = CHAR_BIT - 1 - off % CHAR_BIT;
michael@0:   if (q == CHAR_BIT -1) {
michael@0:     wb->bit_buffer[p] = bit << q;
michael@0:   } else {
michael@0:     wb->bit_buffer[p] &= ~(1 << q);
michael@0:     wb->bit_buffer[p] |= bit << q;
michael@0:   }
michael@0:   wb->bit_offset = off + 1;
michael@0: }
michael@0: 
michael@0: static void vp9_wb_write_literal(struct vp9_write_bit_buffer *wb,
michael@0:                               int data, int bits) {
michael@0:   int bit;
michael@0:   for (bit = bits - 1; bit >= 0; bit--)
michael@0:     vp9_wb_write_bit(wb, (data >> bit) & 1);
michael@0: }
michael@0: 
michael@0: 
michael@0: #endif  // VP9_BIT_WRITE_BUFFER_H_