sharpetronics/zstd
1
0
Fork 0
mirror of https://github.com/facebook/zstd.git synced 2025-10-20 00:04:34 -04:00
Code Issues Projects Releases Wiki Activity

simplified bt

Browse Source
This commit is contained in:
Yann Collet 2015-11-08 15:08:03 +01:00
parent d61ddd03ec
commit e9eba608c2
1 changed files with 6 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
lib/zstdhc.c
View File

@ -316,7 +316,7 @@ size_t ZSTD_HC_compressBlock_fast(ZSTD_HC_CCtx* ctx,
***************************************/ ***************************************/
/** ZSTD_HC_insertBt1 : add one ptr to tree /** ZSTD_HC_insertBt1 : add one ptr to tree
@ip : assumed <= iend-8 */ @ip : assumed <= iend-8 */
static U32 ZSTD_HC_insertBt1(ZSTD_HC_CCtx* zc, const BYTE* ip, const U32 mls, const BYTE* const iend, U32 nbCompares) static U32 ZSTD_HC_insertBt1(ZSTD_HC_CCtx* zc, const BYTE* const ip, const U32 mls, const BYTE* const iend, U32 nbCompares)
{ {
U32* const hashTable = zc->hashTable; U32* const hashTable = zc->hashTable;
const U32 hashLog = zc->params.hashLog; const U32 hashLog = zc->params.hashLog;
@ -329,23 +329,18 @@ static U32 ZSTD_HC_insertBt1(ZSTD_HC_CCtx* zc, const BYTE* ip, const U32 mls, co
const BYTE* const base = zc->base; const BYTE* const base = zc->base;
const BYTE* match = base + matchIndex; const BYTE* match = base + matchIndex;
U32 current = (U32)(ip-base); U32 current = (U32)(ip-base);
U32 btLow = btMask >= current ? 0 : current - btMask; const U32 btLow = btMask >= current ? 0 : current - btMask;
U32* smallerPtr = bt + 2*(current&btMask); U32* smallerPtr = bt + 2*(current&btMask);
U32* largerPtr = bt + 2*(current&btMask) + 1; U32* largerPtr = bt + 2*(current&btMask) + 1;
U32 dummy32; /* to be nullified at the end */ U32 dummy32; /* to be nullified at the end */
const U32 windowSize = 1 << zc->params.windowLog; const U32 windowSize = 1 << zc->params.windowLog;
const U32 windowLow = windowSize >= current ? 0 : current - windowSize; const U32 windowLow = windowSize >= current ? 0 : current - windowSize;
U32 skip = 0;
if ( (current-matchIndex == 1) /* RLE */ if ((current-matchIndex == 1) /* RLE */
&& ZSTD_read_ARCH(match) == ZSTD_read_ARCH(ip)) && ZSTD_read_ARCH(match) == ZSTD_read_ARCH(ip))
{ {
size_t cyclicLength = ZSTD_count(ip+sizeof(size_t), match+sizeof(size_t), iend) + sizeof(size_t); size_t rleLength = ZSTD_count(ip+sizeof(size_t), match+sizeof(size_t), iend) + sizeof(size_t);
skip = (U32)(cyclicLength - mls); /* > 1 */ return (U32)(rleLength - mls);
ip += skip; /* last of segment */
smallerPtr = bt + 2*((current+skip) & btMask);
largerPtr = bt + 2*((current+skip) & btMask) + 1;
btLow += skip;
} }
hashTable[h] = (U32)(ip - base); /* Update Hash Table */ hashTable[h] = (U32)(ip - base); /* Update Hash Table */
@ -382,7 +377,7 @@ static U32 ZSTD_HC_insertBt1(ZSTD_HC_CCtx* zc, const BYTE* ip, const U32 mls, co
} }
*smallerPtr = *largerPtr = 0; *smallerPtr = *largerPtr = 0;
return skip+1; return 1;
} }