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btopt : minor adjustment of update frequencies

dev
Yann Collet 2018-05-10 16:32:36 -07:00
parent ac6105463a
commit 74b1c75d64
2 changed files with 23 additions and 16 deletions
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2
lib/compress/zstd_compress_internal.h
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@ -76,7 +76,7 @@ typedef struct {
U32 rep[ZSTD_REP_NUM];
} ZSTD_optimal_t;
typedef enum { zop_none=0, zop_predef, zop_static } ZSTD_OptPrice_e;
typedef enum { zop_dynamic=0, zop_predef, zop_static } ZSTD_OptPrice_e;
typedef struct {
/* All tables are allocated inside cctx->workspace by ZSTD_resetCCtx_internal() */

37
lib/compress/zstd_opt.c
View File

@ -12,7 +12,7 @@
#include "zstd_opt.h"
#define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats. Also used for matchSum (?) */
#define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats */
#define ZSTD_FREQ_DIV 4 /* log factor when using previous stats to init next stats */
#define ZSTD_MAX_PRICE (1<<30)
@ -32,24 +32,31 @@ static void ZSTD_setLog2Prices(optState_t* optPtr)
static void ZSTD_rescaleFreqs(optState_t* const optPtr,
const BYTE* const src, size_t const srcSize)
{
optPtr->priceType = zop_none;
optPtr->priceType = zop_dynamic;
if (optPtr->litLengthSum == 0) { /* first init */
if (optPtr->litLengthSum == 0) { /* first block : init */
unsigned u;
if (srcSize <= 1024) optPtr->priceType = zop_predef;
if (srcSize <= 1024) /* heuristic */
optPtr->priceType = zop_predef;
assert(optPtr->symbolCosts != NULL);
if (optPtr->symbolCosts->hufCTable_repeatMode == HUF_repeat_valid) { /* huffman table presumed generated by dictionary */
optPtr->priceType = zop_static;
if (srcSize <= 8192) /* heuristic */
optPtr->priceType = zop_static;
else {
assert(optPtr->priceType == zop_dynamic);
}
}
assert(optPtr->litFreq!=NULL);
for (u=0; u<=MaxLit; u++)
optPtr->litFreq[u] = 0;
for (u=0; u<srcSize; u++)
optPtr->litFreq[src[u]]++;
assert(optPtr->litFreq != NULL);
{ unsigned max = MaxLit;
FSE_count(optPtr->litFreq, &max, src, srcSize); /* use raw first block to init statistics */
}
optPtr->litSum = 0;
for (u=0; u<=MaxLit; u++) {
optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> ZSTD_FREQ_DIV);
optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> (ZSTD_FREQ_DIV+1));
optPtr->litSum += optPtr->litFreq[u];
}
@ -63,7 +70,7 @@ static void ZSTD_rescaleFreqs(optState_t* const optPtr,
optPtr->offCodeFreq[u] = 1;
optPtr->offCodeSum = (MaxOff+1);
} else {
} else { /* new block : re-use previous statistics, scaled down */
unsigned u;
optPtr->litSum = 0;
@ -73,17 +80,17 @@ static void ZSTD_rescaleFreqs(optState_t* const optPtr,
}
optPtr->litLengthSum = 0;
for (u=0; u<=MaxLL; u++) {
optPtr->litLengthFreq[u] = 1 + (optPtr->litLengthFreq[u]>>(ZSTD_FREQ_DIV+1));
optPtr->litLengthFreq[u] = 1 + (optPtr->litLengthFreq[u] >> ZSTD_FREQ_DIV);
optPtr->litLengthSum += optPtr->litLengthFreq[u];
}
optPtr->matchLengthSum = 0;
for (u=0; u<=MaxML; u++) {
optPtr->matchLengthFreq[u] = 1 + (optPtr->matchLengthFreq[u]>>ZSTD_FREQ_DIV);
optPtr->matchLengthFreq[u] = 1 + (optPtr->matchLengthFreq[u] >> ZSTD_FREQ_DIV);
optPtr->matchLengthSum += optPtr->matchLengthFreq[u];
}
optPtr->offCodeSum = 0;
for (u=0; u<=MaxOff; u++) {
optPtr->offCodeFreq[u] = 1 + (optPtr->offCodeFreq[u]>>ZSTD_FREQ_DIV);
optPtr->offCodeFreq[u] = 1 + (optPtr->offCodeFreq[u] >> ZSTD_FREQ_DIV);
optPtr->offCodeSum += optPtr->offCodeFreq[u];
}
}