83dcc36b46ff41bff1f9a0385fb317462dc62210
[mirror_edk2.git] / MdeModulePkg / Library / BrotliCustomDecompressLib / dec / bit_reader.c
1 /* Copyright 2013 Google Inc. All Rights Reserved.
2
3 Distributed under MIT license.
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5 */
6
7 /* Bit reading helpers */
8
9 #include "./bit_reader.h"
10
11 #include "../common/types.h"
12 #include "./port.h"
13
14 #if defined(__cplusplus) || defined(c_plusplus)
15 extern "C" {
16 #endif
17
18 void BrotliInitBitReader(BrotliBitReader* const br) {
19 br->val_ = 0;
20 br->bit_pos_ = sizeof(br->val_) << 3;
21 }
22
23 BROTLI_BOOL BrotliWarmupBitReader(BrotliBitReader* const br) {
24 size_t aligned_read_mask = (sizeof(br->val_) >> 1) - 1;
25 /* Fixing alignment after unaligned BrotliFillWindow would result accumulator
26 overflow. If unalignment is caused by BrotliSafeReadBits, then there is
27 enough space in accumulator to fix aligment. */
28 if (!BROTLI_ALIGNED_READ) {
29 aligned_read_mask = 0;
30 }
31 if (BrotliGetAvailableBits(br) == 0) {
32 if (!BrotliPullByte(br)) {
33 return BROTLI_FALSE;
34 }
35 }
36
37 while ((((size_t)br->next_in) & aligned_read_mask) != 0) {
38 if (!BrotliPullByte(br)) {
39 /* If we consumed all the input, we don't care about the alignment. */
40 return BROTLI_TRUE;
41 }
42 }
43 return BROTLI_TRUE;
44 }
45
46 #if defined(__cplusplus) || defined(c_plusplus)
47 } /* extern "C" */
48 #endif