1 files changed, 213 insertions, 0 deletions
diff --git a/lib/zstd/entropy_common.c b/lib/zstd/entropy_common.c
new file mode 100644
index 0000000000..071fef997e
--- /dev/null
+++ b/lib/zstd/entropy_common.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: (GPL-2.0 or BSD-2-Clause)
+/*
+ * Common functions of New Generation Entropy library
+ * Copyright (C) 2016, Yann Collet.
+ *
+ * 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;
+}