/* * Common functions of New Generation Entropy library * Copyright (C) 2016, Yann Collet. * * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * *   * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. *   * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * This program is free software; you can redistribute it and/or modify it under * the terms of the GNU General Public License version 2 as published by the * Free Software Foundation. This program is dual-licensed; you may select * either version 2 of the GNU General Public License ("GPL") or BSD license * ("BSD"). * * You can contact the author at : * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy */ /* **************************************  Dependencies***************************************/#include "error_private.h" /* ERR_*, ERROR */#include "fse.h"#include "huf.h"#include "mem.h" /*===   Version   ===*/unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; } /*===   Error Management   ===*/unsigned FSE_isError(size_t code) { return ERR_isError(code); } unsigned HUF_isError(size_t code) { return ERR_isError(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)		return ERROR(srcSize_wrong);	bitStream = ZSTD_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 = ZSTD_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)) {				ip += bitCount >> 3;				bitCount &= 7;				bitStream = ZSTD_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 = ZSTD_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_wksp(BYTE *huffWeight, size_t hwSize, U32 *rankStats, U32 *nbSymbolsPtr, U32 *tableLogPtr, const void *src, size_t srcSize, void *workspace, size_t workspaceSize){	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) */		if (iSize + 1 > srcSize)			return ERROR(srcSize_wrong);		oSize = FSE_decompress_wksp(huffWeight, hwSize - 1, ip + 1, iSize, 6, workspace, workspaceSize); /* 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;}