/* ZSTD_ldm_skipRawSeqStoreBytes():
* Moves forward in rawSeqStore by nbBytes, updating fields 'pos' and 'posInSequence'.
* Not to be used in conjunction with ZSTD_ldm_skipSequences().
* Must be called for data with is not passed to ZSTD_ldm_blockCompress().
*/
public static void ZSTD_ldm_skipRawSeqStoreBytes(rawSeqStore_t *rawSeqStore, nuint nbBytes)
{
uint currPos = (uint)(rawSeqStore->posInSequence + nbBytes);
while (currPos != 0 && rawSeqStore->pos < rawSeqStore->size)
{
rawSeq currSeq = rawSeqStore->seq[rawSeqStore->pos];
if (currPos >= currSeq.litLength + currSeq.matchLength)
{
currPos -= currSeq.litLength + currSeq.matchLength;
rawSeqStore->pos++;
}
else
{
rawSeqStore->posInSequence = currPos;
break;
}
}
if (currPos == 0 || rawSeqStore->pos == rawSeqStore->size)
{
rawSeqStore->posInSequence = 0;
}
}
/**
* If the sequence length is longer than remaining then the sequence is split
* between this block and the next.
*
* Returns the current sequence to handle, or if the rest of the block should
* be literals, it returns a sequence with offset == 0.
*/
private static rawSeq maybeSplitSequence(rawSeqStore_t *rawSeqStore, uint remaining, uint minMatch)
{
rawSeq sequence = rawSeqStore->seq[rawSeqStore->pos];
assert(sequence.offset > 0);
if (remaining >= sequence.litLength + sequence.matchLength)
{
rawSeqStore->pos++;
return(sequence);
}
if (remaining <= sequence.litLength)
{
sequence.offset = 0;
}
else if (remaining < sequence.litLength + sequence.matchLength)
{
sequence.matchLength = remaining - sequence.litLength;
if (sequence.matchLength < minMatch)
{
sequence.offset = 0;
}
}
ZSTD_ldm_skipSequences(rawSeqStore, remaining, minMatch);
return(sequence);
}
/**
* ZSTD_ldm_blockCompress():
*
* Compresses a block using the predefined sequences, along with a secondary
* block compressor. The literals section of every sequence is passed to the
* secondary block compressor, and those sequences are interspersed with the
* predefined sequences. Returns the length of the last literals.
* Updates `rawSeqStore.pos` to indicate how many sequences have been consumed.
* `rawSeqStore.seq` may also be updated to split the last sequence between two
* blocks.
* @return The length of the last literals.
*
* NOTE: The source must be at most the maximum block size, but the predefined
* sequences can be any size, and may be longer than the block. In the case that
* they are longer than the block, the last sequences may need to be split into
* two. We handle that case correctly, and update `rawSeqStore` appropriately.
* NOTE: This function does not return any errors.
*/
public static nuint ZSTD_ldm_blockCompress(rawSeqStore_t *rawSeqStore, ZSTD_matchState_t *ms, seqStore_t *seqStore, uint *rep, void *src, nuint srcSize)
{
ZSTD_compressionParameters *cParams = &ms->cParams;
uint minMatch = cParams->minMatch;
ZSTD_blockCompressor blockCompressor = ZSTD_selectBlockCompressor(cParams->strategy, ZSTD_matchState_dictMode(ms));
byte *istart = (byte *)(src);
byte *iend = istart + srcSize;
byte *ip = istart;
if (cParams->strategy >= ZSTD_strategy.ZSTD_btopt)
{
nuint lastLLSize;
ms->ldmSeqStore = rawSeqStore;
lastLLSize = blockCompressor(ms, seqStore, rep, src, srcSize);
ZSTD_ldm_skipRawSeqStoreBytes(rawSeqStore, srcSize);
return(lastLLSize);
}
assert(rawSeqStore->pos <= rawSeqStore->size);
assert(rawSeqStore->size <= rawSeqStore->capacity);
while (rawSeqStore->pos < rawSeqStore->size && ip < iend)
{
rawSeq sequence = maybeSplitSequence(rawSeqStore, (uint)(iend - ip), minMatch);
int i;
if (sequence.offset == 0)
{
break;
}
assert(ip + sequence.litLength + sequence.matchLength <= iend);
ZSTD_ldm_limitTableUpdate(ms, ip);
ZSTD_ldm_fillFastTables(ms, (void *)ip);
{
nuint newLitLength = blockCompressor(ms, seqStore, rep, (void *)ip, sequence.litLength);
ip += sequence.litLength;
for (i = 3 - 1; i > 0; i--)
{
rep[i] = rep[i - 1];
}
rep[0] = sequence.offset;
ZSTD_storeSeq(seqStore, newLitLength, ip - newLitLength, iend, sequence.offset + (uint)((3 - 1)), sequence.matchLength - 3);
ip += sequence.matchLength;
}
}
ZSTD_ldm_limitTableUpdate(ms, ip);
ZSTD_ldm_fillFastTables(ms, (void *)ip);
return(blockCompressor(ms, seqStore, rep, (void *)ip, (nuint)(iend - ip)));
}
