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Implement basic splitSequence and skipSequence functions

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This commit is contained in:
senhuang42 2020-09-26 12:09:19 -04:00
parent 634ab7830d
commit 28c74bf591
1 changed files with 51 additions and 5 deletions
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56
lib/compress/zstd_opt.c
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@ -768,15 +768,61 @@ FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches (
* LDM util functions
*********************************/
// The only function that can update pos (i think, for now)
static int ldm_splitSequence(rawSeqStore_t* ldmSeqStore, U32 remainingBytes) {
rawSeq currSeq = ldmSeqStore->seq[ldmSeqStore->pos];
static void ldm_skipSequences(rawSeqStore_t* rawSeqStore, size_t srcSize, U32 const minMatch) {
while (srcSize > 0 && rawSeqStore->pos < rawSeqStore->size) {
rawSeq* seq = rawSeqStore->seq + rawSeqStore->pos;
if (srcSize <= seq->litLength) {
/* Skip past srcSize literals */
seq->litLength -= (U32)srcSize;
return;
}
srcSize -= seq->litLength;
seq->litLength = 0;
if (srcSize < seq->matchLength) {
/* Skip past the first srcSize of the match */
seq->matchLength -= (U32)srcSize;
if (seq->matchLength < minMatch) {
/* The match is too short, omit it */
if (rawSeqStore->pos + 1 < rawSeqStore->size) {
seq[1].litLength += seq[0].matchLength;
}
rawSeqStore->pos++;
}
return;
}
srcSize -= seq->matchLength;
seq->matchLength = 0;
rawSeqStore->pos++;
}
}
// The only function that can update pos (i think, for now)
static rawSeq ldm_splitSequence(rawSeqStore_t* ldmSeqStore, U32 remainingBytes) {
rawSeq currSeq = ldmSeqStore->seq[ldmSeqStore->pos];
/* No split */
if (remainingBytes >= currSeq.litLength + currSeq.matchLength) {
ldmSeqStore->pos++;
return currSeq;
}
/* Need a split */
if (remainingBytes <= currSeq.litLength) {
currSeq.offset = 0;
} else if (remainingBytes < currSeq.litLength + currSeq.matchLength) {
if (currSeq.matchLength < MINMATCH) {
currSeq.offset = 0;
}
}
ldm_skipSequences(ldmSeqStore, remainingBytes, MINMATCH);
return currSeq;
}
/* Returns 1 if the rest of the block is just LDM literals */
static int ldm_getNextMatch(U32* matchStartPosInBlock, U32* matchEndPosInBlock, U32 remainingBytes) {
int ret = ldm_splitSequence();
static int ldm_getNextMatch(rawSeqStore_t* ldmSeqStore,
U32* matchStartPosInBlock, U32* matchEndPosInBlock,
U32 remainingBytes) {
int ret = ldm_splitSequence(ldmSeqStore, remainingBytes);
}
/* Adds an LDM if it's long enough */