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opt: shift all costs by 8 bits (* 256)

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making it possible to represent fractional bit costs.
This commit is contained in:
Yann Collet
2018-05-08 16:19:04 -07:00
parent 6a3c34aa58
commit 1aff63b114
1 changed files with 12 additions and 10 deletions
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lib/compress/zstd_opt.c
+12 -10
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@@ -104,7 +104,7 @@ static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength,
assert(optPtr->symbolCosts->hufCTable_repeatMode == HUF_repeat_valid);
for (u=0, cost=0; u < litLength; u++)
cost += HUF_getNbBits(optPtr->symbolCosts->hufCTable, literals[u]);
return cost;
return cost << 8;
}
if (optPtr->priceType == zop_predef) return (litLength*6); /* 6 bit per literal - no statistic used */
if (litLength == 0) return 0;
@@ -114,7 +114,7 @@ static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength,
U32 cost = litLength * optPtr->log2litSum;
for (u=0; u < litLength; u++)
cost -= ZSTD_highbit32(optPtr->litFreq[literals[u]]+1);
return cost;
return cost << 8;
}
}
@@ -126,13 +126,13 @@ static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optP
U32 const llCode = ZSTD_LLcode(litLength);
FSE_CState_t cstate;
FSE_initCState(&cstate, optPtr->symbolCosts->litlengthCTable);
return LL_bits[llCode] + FSE_getMaxNbBits(cstate.symbolTT, llCode);
return (LL_bits[llCode] + FSE_getMaxNbBits(cstate.symbolTT, llCode)) << 8;
}
if (optPtr->priceType == zop_predef) return ZSTD_highbit32((U32)litLength+1);
/* literal Length */
{ U32 const llCode = ZSTD_LLcode(litLength);
return LL_bits[llCode] + optPtr->log2litLengthSum - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
return (LL_bits[llCode] + optPtr->log2litLengthSum - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1)) << 8;
}
}
@@ -156,15 +156,16 @@ static int ZSTD_litLengthContribution(U32 const litLength, const optState_t* con
U32 const llCode = ZSTD_LLcode(litLength);
FSE_CState_t cstate;
FSE_initCState(&cstate, optPtr->symbolCosts->litlengthCTable);
return (int)(LL_bits[llCode] + FSE_getMaxNbBits(cstate.symbolTT, llCode)) - FSE_getMaxNbBits(cstate.symbolTT, 0);
return ((int)(LL_bits[llCode] + FSE_getMaxNbBits(cstate.symbolTT, llCode)) - FSE_getMaxNbBits(cstate.symbolTT, 0)) * 256;
}
if (optPtr->priceType >= zop_predef) return ZSTD_highbit32(litLength+1);
/* literal Length */
{ U32 const llCode = ZSTD_LLcode(litLength);
int const contribution = LL_bits[llCode]
int const contribution = (LL_bits[llCode]
+ ZSTD_highbit32(optPtr->litLengthFreq[0]+1)
- ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1);
- ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1))
* 256;
#if 1
return contribution;
#else
@@ -204,8 +205,9 @@ ZSTD_getMatchPrice(U32 const offset, U32 const matchLength,
FSE_CState_t mlstate, offstate;
FSE_initCState(&mlstate, optPtr->symbolCosts->matchlengthCTable);
FSE_initCState(&offstate, optPtr->symbolCosts->offcodeCTable);
return FSE_getMaxNbBits(offstate.symbolTT, offCode) + offCode
+ FSE_getMaxNbBits(mlstate.symbolTT, mlCode) + ML_bits[mlCode];
return (FSE_getMaxNbBits(offstate.symbolTT, offCode) + offCode
+ FSE_getMaxNbBits(mlstate.symbolTT, mlCode) + ML_bits[mlCode])
* 256;
}
if (optPtr->priceType == zop_predef) /* fixed scheme, do not use statistics */
@@ -220,7 +222,7 @@ ZSTD_getMatchPrice(U32 const offset, U32 const matchLength,
}
DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price);
return price;
return price << 8;
}
static void ZSTD_updateStats(optState_t* const optPtr,