ddidderr/zstd-rs
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support for skippable frames

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This commit is contained in:
inikep
2016-05-31 12:43:46 +02:00
parent d57b418214
commit f772bf54a5
6 changed files with 66 additions and 12 deletions
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lib/decompress/zbuff_decompress.c
+20 -4
View File
@@ -218,12 +218,19 @@ size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbd,
break;
}
if ((size_t)(iend-ip) >= neededInSize) { /* decode directly from src */
const int isSkipFrame = ZSTD_isSkipFrame(zbd->zd);
size_t const decodedSize = ZSTD_decompressContinue(zbd->zd,
zbd->outBuff + zbd->outStart, zbd->outBuffSize - zbd->outStart,
zbd->outBuff + zbd->outStart, (isSkipFrame ? 0 : zbd->outBuffSize - zbd->outStart),
ip, neededInSize);
if (ZSTD_isError(decodedSize)) return decodedSize;
ip += neededInSize;
if (!decodedSize) break; /* this was just a header */
if (!decodedSize) {
if (isSkipFrame) {
zbd->stage = ZBUFFds_loadHeader;
zbd->lhSize = 0;
}
break; /* this was just a header */
}
zbd->outEnd = zbd->outStart + decodedSize;
zbd->stage = ZBUFFds_flush;
break;
@@ -243,12 +250,21 @@ size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbd,
if (loadedSize < toLoad) { notDone = 0; break; } /* not enough input, wait for more */
/* decode loaded input */
{ size_t const decodedSize = ZSTD_decompressContinue(zbd->zd,
{ const int isSkipFrame = ZSTD_isSkipFrame(zbd->zd);
size_t const decodedSize = ZSTD_decompressContinue(zbd->zd,
zbd->outBuff + zbd->outStart, zbd->outBuffSize - zbd->outStart,
zbd->inBuff, neededInSize);
if (ZSTD_isError(decodedSize)) return decodedSize;
zbd->inPos = 0; /* input is consumed */
if (!decodedSize) { zbd->stage = ZBUFFds_read; break; } /* this was just a header */
if (!decodedSize) {
if (isSkipFrame) {
zbd->stage = ZBUFFds_loadHeader;
zbd->lhSize = 0;
break;
}
zbd->stage = ZBUFFds_read; /* this was just a header */
break;
}
zbd->outEnd = zbd->outStart + decodedSize;
zbd->stage = ZBUFFds_flush;
// break; /* ZBUFFds_flush follows */
lib/decompress/zstd_decompress.c
+33 -2
View File
@@ -101,7 +101,8 @@ static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }
* Context management
***************************************************************/
typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader,
ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock } ZSTD_dStage;
ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock,
ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage;
struct ZSTD_DCtx_s
{
@@ -312,7 +313,15 @@ size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t
const BYTE* ip = (const BYTE*)src;
if (srcSize < ZSTD_frameHeaderSize_min) return ZSTD_frameHeaderSize_min;
if (MEM_readLE32(src) != ZSTD_MAGICNUMBER) return ERROR(prefix_unknown);
if (MEM_readLE32(src) != ZSTD_MAGICNUMBER) {
if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
if (srcSize < ZSTD_skippableHeaderSize) return ZSTD_skippableHeaderSize; /* magic number + skippable frame length */
fparamsPtr->frameContentSize = 0;
fparamsPtr->windowLog = ZSTD_WINDOWLOG_ABSOLUTEMIN;
return 0;
}
return ERROR(prefix_unknown);
}
/* ensure there is enough `srcSize` to fully read/decode frame header */
{ size_t const fhsize = ZSTD_frameHeaderSize(src, srcSize);
@@ -995,6 +1004,11 @@ size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx)
return dctx->expected;
}
int ZSTD_isSkipFrame(ZSTD_DCtx* dctx)
{
return dctx->stage == ZSTDds_skipFrame;
}
size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
/* Sanity check */
@@ -1006,6 +1020,12 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, c
{
case ZSTDds_getFrameHeaderSize :
if (srcSize != ZSTD_frameHeaderSize_min) return ERROR(srcSize_wrong); /* impossible */
if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_min);
dctx->expected = ZSTD_skippableHeaderSize - ZSTD_frameHeaderSize_min; /* magic number + skippable frame length */
dctx->stage = ZSTDds_decodeSkippableHeader;
return 0;
}
dctx->headerSize = ZSTD_frameHeaderSize(src, ZSTD_frameHeaderSize_min);
if (ZSTD_isError(dctx->headerSize)) return dctx->headerSize;
memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_min);
@@ -1063,6 +1083,17 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, c
dctx->previousDstEnd = (char*)dst + rSize;
return rSize;
}
case ZSTDds_decodeSkippableHeader:
{ memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_min, src, dctx->expected);
dctx->expected = MEM_readLE32(dctx->headerBuffer + 4);
dctx->stage = ZSTDds_skipFrame;
return 0;
}
case ZSTDds_skipFrame:
{ dctx->expected = ZSTD_frameHeaderSize_min;
dctx->stage = ZSTDds_getFrameHeaderSize;
return 0;
}
default:
return ERROR(GENERIC); /* impossible */
}