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simplifications

dev
Yann Collet 2016-03-18 22:23:49 +01:00
parent 39c596ca58
commit 4db09efde4
2 changed files with 62 additions and 85 deletions
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141
lib/zstd_decompress.c
View File

@ -508,6 +508,39 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
}
/*! ZSTD_buildSeqTable() :
@return : nb bytes read from src,
or an error code if it fails, testable with ZSTD_isError()
*/
static size_t ZSTD_buildSeqTable(FSE_DTable* DTable, U32 type, U32 rawBits, U32 maxLog,
const void* src, size_t srcSize)
{
switch(type)
{
case FSE_ENCODING_RLE :
if (!srcSize) return ERROR(srcSize_wrong);
FSE_buildDTable_rle(DTable, *(const BYTE*)src);
return 1;
case FSE_ENCODING_RAW :
FSE_buildDTable_raw(DTable, rawBits);
return 0;
case FSE_ENCODING_STATIC:
return 0;
default : /* impossible */
case FSE_ENCODING_DYNAMIC :
{ U32 tableLog, max = (1<<rawBits)-1;
S16 norm[MaxSeq+1];
size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
if (FSE_isError(headerSize)) return ERROR(GENERIC);
if (tableLog > maxLog) return ERROR(corruption_detected);
FSE_buildDTable(DTable, norm, max, tableLog);
return headerSize;
} }
}
size_t ZSTD_decodeSeqHeaders(int* nbSeq, const BYTE** dumpsPtr, size_t* dumpsLengthPtr,
FSE_DTable* DTableLL, FSE_DTable* DTableML, FSE_DTable* DTableOffb,
const void* src, size_t srcSize)
@ -516,11 +549,9 @@ size_t ZSTD_decodeSeqHeaders(int* nbSeq, const BYTE** dumpsPtr, size_t* dumpsLen
const BYTE* ip = istart;
const BYTE* const iend = istart + srcSize;
U32 LLtype, Offtype, MLtype;
size_t dumpsLength;
/* check */
if (srcSize < MIN_SEQUENCES_SIZE)
return ERROR(srcSize_wrong);
if (srcSize < MIN_SEQUENCES_SIZE) return ERROR(srcSize_wrong);
/* SeqHead */
*nbSeq = *ip++;
@ -536,91 +567,37 @@ size_t ZSTD_decodeSeqHeaders(int* nbSeq, const BYTE** dumpsPtr, size_t* dumpsLen
LLtype = *ip >> 6;
Offtype = (*ip >> 4) & 3;
MLtype = (*ip >> 2) & 3;
if (*ip & 2) {
dumpsLength = ip[2];
dumpsLength += ip[1] << 8;
ip += 3;
} else {
dumpsLength = ip[1];
dumpsLength += (ip[0] & 1) << 8;
ip += 2;
{ size_t dumpsLength;
if (*ip & 2) {
dumpsLength = ip[2];
dumpsLength += ip[1] << 8;
ip += 3;
} else {
dumpsLength = ip[1];
dumpsLength += (ip[0] & 1) << 8;
ip += 2;
}
*dumpsPtr = ip;
ip += dumpsLength;
*dumpsLengthPtr = dumpsLength;
}
*dumpsPtr = ip;
ip += dumpsLength;
*dumpsLengthPtr = dumpsLength;
/* check */
if (ip > iend-3) return ERROR(srcSize_wrong); /* min : all 3 are "raw", hence no header, but at least xxLog bits per type */
/* Build DTables */
{
S16 norm[MaxML+1]; /* assumption : MaxML >= MaxLL >= MaxOff */
switch(LLtype)
{
case FSE_ENCODING_RLE :
FSE_buildDTable_rle(DTableLL, *ip++);
break;
case FSE_ENCODING_RAW :
FSE_buildDTable_raw(DTableLL, LLbits);
break;
case FSE_ENCODING_STATIC:
break;
default : /* impossible */
case FSE_ENCODING_DYNAMIC :
{ U32 LLlog, max = MaxLL;
size_t const headerSize = FSE_readNCount(norm, &max, &LLlog, ip, iend-ip);
if (FSE_isError(headerSize)) return ERROR(GENERIC);
if (LLlog > LLFSELog) return ERROR(corruption_detected);
ip += headerSize;
FSE_buildDTable(DTableLL, norm, max, LLlog);
}
}
switch(Offtype)
{
case FSE_ENCODING_RLE :
if (ip > iend-2) return ERROR(srcSize_wrong); /* min : "raw", hence no header, but at least xxLog bits */
FSE_buildDTable_rle(DTableOffb, *ip++ & MaxOff); /* if *ip > MaxOff, data is corrupted */
break;
case FSE_ENCODING_RAW :
FSE_buildDTable_raw(DTableOffb, Offbits);
break;
case FSE_ENCODING_STATIC:
break;
default : /* impossible */
case FSE_ENCODING_DYNAMIC :
{
U32 Offlog, max = MaxOff;
size_t const headerSize = FSE_readNCount(norm, &max, &Offlog, ip, iend-ip);
if (FSE_isError(headerSize)) return ERROR(GENERIC);
if (Offlog > OffFSELog) return ERROR(corruption_detected);
ip += headerSize;
FSE_buildDTable(DTableOffb, norm, max, Offlog);
}
}
switch(MLtype)
{
case FSE_ENCODING_RLE :
if (ip > iend-2) return ERROR(srcSize_wrong); /* min : "raw", hence no header, but at least xxLog bits */
FSE_buildDTable_rle(DTableML, *ip++);
break;
case FSE_ENCODING_RAW :
FSE_buildDTable_raw(DTableML, MLbits);
break;
case FSE_ENCODING_STATIC:
break;
default : /* impossible */
case FSE_ENCODING_DYNAMIC :
{ U32 MLlog, max = MaxML;
size_t const headerSize = FSE_readNCount(norm, &max, &MLlog, ip, iend-ip);
if (FSE_isError(headerSize)) return ERROR(GENERIC);
if (MLlog > MLFSELog) return ERROR(corruption_detected);
ip += headerSize;
FSE_buildDTable(DTableML, norm, max, MLlog);
}
} } /* Build DTables */
{ size_t const bhSize = ZSTD_buildSeqTable(DTableLL, LLtype, LLbits, LLFSELog, ip, iend-ip);
if (ZSTD_isError(bhSize)) return ERROR(corruption_detected);
ip += bhSize;
}
{ size_t const bhSize = ZSTD_buildSeqTable(DTableOffb, Offtype, Offbits, OffFSELog, ip, iend-ip);
if (ZSTD_isError(bhSize)) return ERROR(corruption_detected);
ip += bhSize;
}
{ size_t const bhSize = ZSTD_buildSeqTable(DTableML, MLtype, MLbits, MLFSELog, ip, iend-ip);
if (ZSTD_isError(bhSize)) return ERROR(corruption_detected);
ip += bhSize;
}
return ip-istart;
}

6
lib/zstd_internal.h
View File

@ -90,6 +90,8 @@ static const size_t ZSTD_blockHeaderSize = ZSTD_BLOCKHEADERSIZE;
#define REPCODE_STARTVALUE 1
#define ZSTD_WINDOWLOG_ABSOLUTEMIN 12
#define LONGNBSEQ 0x7F00
#define Litbits 8
#define MLbits 7
#define LLbits 6
@ -101,9 +103,7 @@ static const size_t ZSTD_blockHeaderSize = ZSTD_BLOCKHEADERSIZE;
#define MLFSELog 10
#define LLFSELog 10
#define OffFSELog 9
#define MaxSeq MAX(MaxLL, MaxML)
#define LONGNBSEQ 0x7F00
#define MaxSeq MAX(MaxLL, MaxML) /* Assumption : MaxOff < MaxLL,MaxML */
#define FSE_ENCODING_RAW 0
#define FSE_ENCODING_RLE 1