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Fix "zero-distance-code", take 2 (#506)

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Eugene Kliuchnikov 2017-02-08 21:14:01 +01:00 committed by GitHub
parent 0749d9ca8b
commit 9fa1ad5a91
2 changed files with 4 additions and 2 deletions
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4
dec/decode.c
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@ -1446,6 +1446,7 @@ static BROTLI_INLINE BROTLI_BOOL ReadDistanceInternal(
}
/* Convert the distance code to the actual distance by possibly */
/* looking up past distances from the s->ringbuffer. */
s->distance_context = 0;
if ((s->distance_code & ~0xf) == 0) {
TakeDistanceFromRingBuffer(s);
--s->block_length[2];
@ -1706,6 +1707,7 @@ CommandPostDecodeLiterals:
s->state = BROTLI_STATE_COMMAND_POST_DECODE_LITERALS;
}
if (s->distance_code >= 0) {
s->distance_context = s->distance_code ? 0 : 1;
--s->dist_rb_idx;
s->distance_code = s->dist_rb[s->dist_rb_idx & 3];
goto postReadDistance; /* We already have the implicit distance */
@ -1714,8 +1716,6 @@ CommandPostDecodeLiterals:
if (BROTLI_PREDICT_FALSE(s->block_length[2] == 0)) {
BROTLI_SAFE(DecodeDistanceBlockSwitch(s));
}
/* Reuse distance_context variable. */
s->distance_context = 0;
BROTLI_SAFE(ReadDistance(s, br));
postReadDistance:
BROTLI_LOG(("[ProcessCommandsInternal] pos = %d distance = %d\n",

2
dec/state.h
View File

@ -140,6 +140,8 @@ struct BrotliDecoderStateStruct {
/* This is true if the literal context map histogram type always matches the
block type. It is then not needed to keep the context (faster decoding). */
int trivial_literal_context;
/* Distance context is actual after command is decoded and before distance
is computed. After distance computation it is used as a temporary variable. */
int distance_context;
int meta_block_remaining_len;
uint32_t block_length_index;