216 lines
8.4 KiB
C
216 lines
8.4 KiB
C
/* ******************************************************************
|
|
* Common functions of New Generation Entropy library
|
|
* Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
|
|
*
|
|
* You can contact the author at :
|
|
* - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
|
|
* - Public forum : https://groups.google.com/forum/#!forum/lz4c
|
|
*
|
|
* This source code is licensed under both the BSD-style license (found in the
|
|
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
|
|
* in the COPYING file in the root directory of this source tree).
|
|
* You may select, at your option, one of the above-listed licenses.
|
|
****************************************************************** */
|
|
|
|
/* *************************************
|
|
* Dependencies
|
|
***************************************/
|
|
#include "mem.h"
|
|
#include "error_private.h" /* ERR_*, ERROR */
|
|
#define FSE_STATIC_LINKING_ONLY /* FSE_MIN_TABLELOG */
|
|
#include "fse.h"
|
|
#define HUF_STATIC_LINKING_ONLY /* HUF_TABLELOG_ABSOLUTEMAX */
|
|
#include "huf.h"
|
|
|
|
|
|
/*=== Version ===*/
|
|
unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
|
|
|
|
|
|
/*=== Error Management ===*/
|
|
unsigned FSE_isError(size_t code) { return ERR_isError(code); }
|
|
const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }
|
|
|
|
unsigned HUF_isError(size_t code) { return ERR_isError(code); }
|
|
const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }
|
|
|
|
|
|
/*-**************************************************************
|
|
* FSE NCount encoding-decoding
|
|
****************************************************************/
|
|
size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
|
|
const void* headerBuffer, size_t hbSize)
|
|
{
|
|
const BYTE* const istart = (const BYTE*) headerBuffer;
|
|
const BYTE* const iend = istart + hbSize;
|
|
const BYTE* ip = istart;
|
|
int nbBits;
|
|
int remaining;
|
|
int threshold;
|
|
U32 bitStream;
|
|
int bitCount;
|
|
unsigned charnum = 0;
|
|
int previous0 = 0;
|
|
|
|
if (hbSize < 4) {
|
|
/* This function only works when hbSize >= 4 */
|
|
char buffer[4];
|
|
memset(buffer, 0, sizeof(buffer));
|
|
memcpy(buffer, headerBuffer, hbSize);
|
|
{ size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,
|
|
buffer, sizeof(buffer));
|
|
if (FSE_isError(countSize)) return countSize;
|
|
if (countSize > hbSize) return ERROR(corruption_detected);
|
|
return countSize;
|
|
} }
|
|
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);
|
|
nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
|
|
if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
|
|
bitStream >>= 4;
|
|
bitCount = 4;
|
|
*tableLogPtr = nbBits;
|
|
remaining = (1<<nbBits)+1;
|
|
threshold = 1<<nbBits;
|
|
nbBits++;
|
|
|
|
while ((remaining>1) & (charnum<=*maxSVPtr)) {
|
|
if (previous0) {
|
|
unsigned n0 = charnum;
|
|
while ((bitStream & 0xFFFF) == 0xFFFF) {
|
|
n0 += 24;
|
|
if (ip < iend-5) {
|
|
ip += 2;
|
|
bitStream = MEM_readLE32(ip) >> bitCount;
|
|
} else {
|
|
bitStream >>= 16;
|
|
bitCount += 16;
|
|
} }
|
|
while ((bitStream & 3) == 3) {
|
|
n0 += 3;
|
|
bitStream >>= 2;
|
|
bitCount += 2;
|
|
}
|
|
n0 += bitStream & 3;
|
|
bitCount += 2;
|
|
if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall);
|
|
while (charnum < n0) normalizedCounter[charnum++] = 0;
|
|
if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
|
|
assert((bitCount >> 3) <= 3); /* For first condition to work */
|
|
ip += bitCount>>3;
|
|
bitCount &= 7;
|
|
bitStream = MEM_readLE32(ip) >> bitCount;
|
|
} else {
|
|
bitStream >>= 2;
|
|
} }
|
|
{ int const max = (2*threshold-1) - remaining;
|
|
int count;
|
|
|
|
if ((bitStream & (threshold-1)) < (U32)max) {
|
|
count = bitStream & (threshold-1);
|
|
bitCount += nbBits-1;
|
|
} else {
|
|
count = bitStream & (2*threshold-1);
|
|
if (count >= threshold) count -= max;
|
|
bitCount += nbBits;
|
|
}
|
|
|
|
count--; /* extra accuracy */
|
|
remaining -= count < 0 ? -count : count; /* -1 means +1 */
|
|
normalizedCounter[charnum++] = (short)count;
|
|
previous0 = !count;
|
|
while (remaining < threshold) {
|
|
nbBits--;
|
|
threshold >>= 1;
|
|
}
|
|
|
|
if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
|
|
ip += bitCount>>3;
|
|
bitCount &= 7;
|
|
} else {
|
|
bitCount -= (int)(8 * (iend - 4 - ip));
|
|
ip = iend - 4;
|
|
}
|
|
bitStream = MEM_readLE32(ip) >> (bitCount & 31);
|
|
} } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
|
|
if (remaining != 1) return ERROR(corruption_detected);
|
|
if (bitCount > 32) return ERROR(corruption_detected);
|
|
*maxSVPtr = charnum-1;
|
|
|
|
ip += (bitCount+7)>>3;
|
|
return ip-istart;
|
|
}
|
|
|
|
|
|
/*! HUF_readStats() :
|
|
Read compact Huffman tree, saved by HUF_writeCTable().
|
|
`huffWeight` is destination buffer.
|
|
`rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
|
|
@return : size read from `src` , or an error Code .
|
|
Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
|
|
*/
|
|
size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
|
|
U32* nbSymbolsPtr, U32* tableLogPtr,
|
|
const void* src, size_t srcSize)
|
|
{
|
|
U32 weightTotal;
|
|
const BYTE* ip = (const BYTE*) src;
|
|
size_t iSize;
|
|
size_t oSize;
|
|
|
|
if (!srcSize) return ERROR(srcSize_wrong);
|
|
iSize = ip[0];
|
|
/* memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */
|
|
|
|
if (iSize >= 128) { /* special header */
|
|
oSize = iSize - 127;
|
|
iSize = ((oSize+1)/2);
|
|
if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
|
|
if (oSize >= hwSize) return ERROR(corruption_detected);
|
|
ip += 1;
|
|
{ U32 n;
|
|
for (n=0; n<oSize; n+=2) {
|
|
huffWeight[n] = ip[n/2] >> 4;
|
|
huffWeight[n+1] = ip[n/2] & 15;
|
|
} } }
|
|
else { /* header compressed with FSE (normal case) */
|
|
FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(6)]; /* 6 is max possible tableLog for HUF header (maybe even 5, to be tested) */
|
|
if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
|
|
oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 6); /* max (hwSize-1) values decoded, as last one is implied */
|
|
if (FSE_isError(oSize)) return oSize;
|
|
}
|
|
|
|
/* collect weight stats */
|
|
memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
|
|
weightTotal = 0;
|
|
{ U32 n; for (n=0; n<oSize; n++) {
|
|
if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected);
|
|
rankStats[huffWeight[n]]++;
|
|
weightTotal += (1 << huffWeight[n]) >> 1;
|
|
} }
|
|
if (weightTotal == 0) return ERROR(corruption_detected);
|
|
|
|
/* get last non-null symbol weight (implied, total must be 2^n) */
|
|
{ U32 const tableLog = BIT_highbit32(weightTotal) + 1;
|
|
if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
|
|
*tableLogPtr = tableLog;
|
|
/* determine last weight */
|
|
{ U32 const total = 1 << tableLog;
|
|
U32 const rest = total - weightTotal;
|
|
U32 const verif = 1 << BIT_highbit32(rest);
|
|
U32 const lastWeight = BIT_highbit32(rest) + 1;
|
|
if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */
|
|
huffWeight[oSize] = (BYTE)lastWeight;
|
|
rankStats[lastWeight]++;
|
|
} }
|
|
|
|
/* check tree construction validity */
|
|
if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
|
|
|
|
/* results */
|
|
*nbSymbolsPtr = (U32)(oSize+1);
|
|
return iSize+1;
|
|
}
|