AuroraMiddleware/zstd
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zeroise freq table with memset()

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improves decoding speed by ~5% in github_users sample set
This commit is contained in:
Yann Collet 2018-06-26 17:24:41 -07:00
parent 25f3d54c40
commit ff773bfcde
1 changed files with 2 additions and 5 deletions
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7
lib/common/entropy_common.c
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@ -85,6 +85,8 @@ size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* t
} } } }
assert(hbSize >= 4); assert(hbSize >= 4);
/* init */
memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */
bitStream = MEM_readLE32(ip); bitStream = MEM_readLE32(ip);
nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */ nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge); if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
@ -156,11 +158,6 @@ size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* t
} } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */ } } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
if (remaining != 1) return ERROR(corruption_detected); if (remaining != 1) return ERROR(corruption_detected);
if (bitCount > 32) return ERROR(corruption_detected); if (bitCount > 32) return ERROR(corruption_detected);
/* zeroise the rest */
{ unsigned symbNb = charnum;
for (symbNb=charnum; symbNb <= *maxSVPtr; symbNb++)
normalizedCounter[symbNb] = 0;
}
*maxSVPtr = charnum-1; *maxSVPtr = charnum-1;
ip += (bitCount+7)>>3; ip += (bitCount+7)>>3;