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Forbiding emission of RLE when its the first block

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This commit is contained in:
bimbashrestha 2019-08-26 14:54:29 -07:00
parent 33b6446ca7
commit ce264ce53b
1 changed files with 15 additions and 4 deletions
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19
lib/compress/zstd_compress.c
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@ -2276,7 +2276,7 @@ static int ZSTD_isRLE(const BYTE *ip, size_t length) {
static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize)
const void* src, size_t srcSize, U32 frame)
{
/*
This the upper bound for the length of an rle block.
@ -2305,7 +2305,18 @@ static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc,
zc->entropyWorkspace, HUF_WORKSPACE_SIZE /* statically allocated in resetCCtx */,
zc->bmi2);
if (cSize < rleMaxLength && ZSTD_isRLE(ip, srcSize)) {
/*
We don't want to emit our first block as a RLE even if it qualifies because
doing so will cause the decoder to throw a "should consume all input error."
https://github.com/facebook/zstd/blob/dev/programs/fileio.c#L1723
*/
U32 isFirstBlock = zc->inBuffPos == srcSize;
if (frame &&
!isFirstBlock &&
cSize < rleMaxLength &&
ZSTD_isRLE(ip, srcSize))
{
cSize = 1;
op[0] = ip[0];
}
@ -2387,7 +2398,7 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx,
{ size_t cSize = ZSTD_compressBlock_internal(cctx,
op+ZSTD_blockHeaderSize, dstCapacity-ZSTD_blockHeaderSize,
ip, blockSize);
ip, blockSize, 1 /* frame */);
FORWARD_IF_ERROR(cSize);
if (cSize == 0) { /* block is not compressible */
@ -2527,7 +2538,7 @@ static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* cctx,
DEBUGLOG(5, "ZSTD_compressContinue_internal (blockSize=%u)", (unsigned)cctx->blockSize);
{ size_t const cSize = frame ?
ZSTD_compress_frameChunk (cctx, dst, dstCapacity, src, srcSize, lastFrameChunk) :
ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize);
ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize, 0 /* frame */);
FORWARD_IF_ERROR(cSize);
cctx->consumedSrcSize += srcSize;
cctx->producedCSize += (cSize + fhSize);