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fixed lz4 compression starting at small address

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when using byU32 and byU16 modes
This commit is contained in:
test4973 2018-04-05 12:40:33 -07:00
parent 43132af808
commit 6d931b6a93
2 changed files with 68 additions and 4 deletions
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70
lib/lz4.c
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@ -533,6 +533,20 @@ LZ4_FORCE_INLINE void LZ4_putPosition(const BYTE* p, void* tableBase, tableType_
LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
}
/* LZ4_getIndexOnHash() :
* Index of match position registered in hash table.
* hash position must be calculated by using base+index, or dictBase+index.
* Assumption 1 : only valid if tableType == byU32 or byU16.
* Assumption 2 : h is presumed valid (within limits of hash table)
*/
static U32 LZ4_getIndexOnHash(U32 h, const void* tableBase, tableType_t tableType)
{
LZ4_STATIC_ASSERT(LZ4_MEMORY_USAGE > 2);
if (tableType == byU32) { const U32* const hashTable = (const U32*) tableBase; assert(h < (1U << (LZ4_MEMORY_USAGE-2))); return hashTable[h]; }
if (tableType == byU16) { const U16* const hashTable = (const U16*) tableBase; assert(h < (1U << (LZ4_MEMORY_USAGE-1))); return hashTable[h]; }
assert(0); return 0; /* forbidden case */
}
static const BYTE* LZ4_getPositionOnHash(U32 h, const void* tableBase, tableType_t tableType, const BYTE* srcBase)
{
if (tableType == byPtr) { const BYTE* const* hashTable = (const BYTE* const*) tableBase; return hashTable[h]; }
@ -598,7 +612,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
{
const BYTE* ip = (const BYTE*) source;
size_t currentOffset = cctx->currentOffset;
size_t const currentOffset = cctx->currentOffset;
const BYTE* base = (const BYTE*) source - currentOffset;
const BYTE* lowLimit;
@ -650,7 +664,8 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
BYTE* token;
/* Find a match */
{ const BYTE* forwardIp = ip;
if (tableType == byPtr) {
const BYTE* forwardIp = ip;
unsigned step = 1;
unsigned searchMatchNb = acceleration << LZ4_skipTrigger;
do {
@ -687,6 +702,54 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
} while ( ((dictIssue==dictSmall) ? (match < lowRefLimit) : 0)
|| ((tableType==byU16) ? 0 : (match + MAX_DISTANCE < ip))
|| (LZ4_read32(match+refDelta) != LZ4_read32(ip)) );
} else { /* byU32, byU16 */
const BYTE* forwardIp = ip;
unsigned step = 1;
unsigned searchMatchNb = acceleration << LZ4_skipTrigger;
do {
U32 const h = forwardH;
U32 const matchIndex = LZ4_getIndexOnHash(h, cctx->hashTable, tableType);
ip = forwardIp;
forwardIp += step;
step = (searchMatchNb++ >> LZ4_skipTrigger);
if (unlikely(forwardIp > mflimitPlusOne)) goto _last_literals;
assert(ip < mflimitPlusOne);
if (dictDirective == usingDictCtx) {
if (matchIndex < currentOffset) {
/* there was no match, try the dictionary */
match = LZ4_getPosition(ip, dictCtx->hashTable, byU32, dictBase);
refDelta = dictDelta;
lowLimit = dictLowLimit;
} else {
match = base + matchIndex;
refDelta = 0;
lowLimit = (const BYTE*)source;
}
} else if (dictDirective==usingExtDict) {
if (matchIndex < currentOffset) {
match = dictBase + matchIndex;
refDelta = dictDelta;
lowLimit = dictLowLimit;
} else {
match = base + matchIndex;
refDelta = 0;
lowLimit = (const BYTE*)source;
}
} else { /* single continuous memory segment */
match = base + matchIndex;
refDelta = 0;
lowLimit = (const BYTE*)source;
}
forwardH = LZ4_hashPosition(forwardIp, tableType);
LZ4_putPositionOnHash(ip, h, cctx->hashTable, tableType, base);
} while ( ((dictIssue==dictSmall) ? (match < lowRefLimit) : 0)
|| ((tableType==byU16) ? 0 : (match + MAX_DISTANCE < ip))
|| (LZ4_read32(match+refDelta) != LZ4_read32(ip)) );
}
/* Catch up */
@ -718,7 +781,8 @@ _next_match:
/* Encode MatchLength */
{ unsigned matchCode;
if ((dictDirective==usingExtDict || dictDirective==usingDictCtx) && lowLimit==dictionary) {
if ( (dictDirective==usingExtDict || dictDirective==usingDictCtx)
&& (lowLimit==dictionary) ) {
const BYTE* limit;
match += refDelta;
limit = ip + (dictEnd-match);

2
tests/fuzzer.c
View File

@ -322,7 +322,7 @@ static int FUZ_test(U32 seed, U32 nbCycles, const U32 startCycle, const double c
# define FUZ_DISPLAYTEST(...) { \
testNb++; \
if (g_displayLevel>=4) { \
printf("\r%4u - %2u ", seed, testNb); \
printf("\r%4u - %2u ", cycleNb, testNb); \
printf(" " __VA_ARGS__); \
printf(" "); \
fflush(stdout); \