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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 <stdlib.h>
13 
14 #include "./vpx_config.h"
15 #include "./bitwriter_buffer.h"
16 
vpx_wb_bytes_written(const struct vpx_write_bit_buffer * wb)17 size_t vpx_wb_bytes_written(const struct vpx_write_bit_buffer *wb) {
18   return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
19 }
20 
vpx_wb_write_bit(struct vpx_write_bit_buffer * wb,int bit)21 void vpx_wb_write_bit(struct vpx_write_bit_buffer *wb, int bit) {
22   const int off = (int)wb->bit_offset;
23   const int p = off / CHAR_BIT;
24   const int q = CHAR_BIT - 1 - off % CHAR_BIT;
25   if (q == CHAR_BIT - 1) {
26     wb->bit_buffer[p] = bit << q;
27   } else {
28     wb->bit_buffer[p] &= ~(1 << q);
29     wb->bit_buffer[p] |= bit << q;
30   }
31   wb->bit_offset = off + 1;
32 }
33 
vpx_wb_write_literal(struct vpx_write_bit_buffer * wb,int data,int bits)34 void vpx_wb_write_literal(struct vpx_write_bit_buffer *wb, int data, int bits) {
35   int bit;
36   for (bit = bits - 1; bit >= 0; bit--) vpx_wb_write_bit(wb, (data >> bit) & 1);
37 }
38 
vpx_wb_write_inv_signed_literal(struct vpx_write_bit_buffer * wb,int data,int bits)39 void vpx_wb_write_inv_signed_literal(struct vpx_write_bit_buffer *wb, int data,
40                                      int bits) {
41   vpx_wb_write_literal(wb, abs(data), bits);
42   vpx_wb_write_bit(wb, data < 0);
43 }
44