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