1 files changed, 302 insertions, 0 deletions
diff --git a/lib/zstd/fse_decompress.c b/lib/zstd/fse_decompress.c
new file mode 100644
index 00000000000..3b4522b427d
--- /dev/null
+++ b/lib/zstd/fse_decompress.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: (GPL-2.0 or BSD-2-Clause)
+/*
+ * FSE : Finite State Entropy decoder
+ * Copyright (C) 2013-2015, Yann Collet.
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* **************************************************************
+*  Compiler specifics
+****************************************************************/
+#define FORCE_INLINE static __always_inline
+
+/* **************************************************************
+*  Includes
+****************************************************************/
+#include "bitstream.h"
+#include "fse.h"
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/string.h> /* memcpy, memset */
+
+/* **************************************************************
+*  Error Management
+****************************************************************/
+#define FSE_isError ERR_isError
+#define FSE_STATIC_ASSERT(c)                                   \
+	{                                                      \
+		enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
+	} /* use only *after* variable declarations */
+
+/* check and forward error code */
+#define CHECK_F(f)                  \
+	{                           \
+		size_t const e = f; \
+		if (FSE_isError(e)) \
+			return e;   \
+	}
+
+/* **************************************************************
+*  Templates
+****************************************************************/
+/*
+  designed to be included
+  for type-specific functions (template emulation in C)
+  Objective is to write these functions only once, for improved maintenance
+*/
+
+/* safety checks */
+#ifndef FSE_FUNCTION_EXTENSION
+#error "FSE_FUNCTION_EXTENSION must be defined"
+#endif
+#ifndef FSE_FUNCTION_TYPE
+#error "FSE_FUNCTION_TYPE must be defined"
+#endif
+
+/* Function names */
+#define FSE_CAT(X, Y) X##Y
+#define FSE_FUNCTION_NAME(X, Y) FSE_CAT(X, Y)
+#define FSE_TYPE_NAME(X, Y) FSE_CAT(X, Y)
+
+/* Function templates */
+
+size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)
+{
+	void *const tdPtr = dt + 1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
+	FSE_DECODE_TYPE *const tableDecode = (FSE_DECODE_TYPE *)(tdPtr);
+	U16 *symbolNext = (U16 *)workspace;
+
+	U32 const maxSV1 = maxSymbolValue + 1;
+	U32 const tableSize = 1 << tableLog;
+	U32 highThreshold = tableSize - 1;
+
+	/* Sanity Checks */
+	if (workspaceSize < sizeof(U16) * (FSE_MAX_SYMBOL_VALUE + 1))
+		return ERROR(tableLog_tooLarge);
+	if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE)
+		return ERROR(maxSymbolValue_tooLarge);
+	if (tableLog > FSE_MAX_TABLELOG)
+		return ERROR(tableLog_tooLarge);
+
+	/* Init, lay down lowprob symbols */
+	{
+		FSE_DTableHeader DTableH;
+		DTableH.tableLog = (U16)tableLog;
+		DTableH.fastMode = 1;
+		{
+			S16 const largeLimit = (S16)(1 << (tableLog - 1));
+			U32 s;
+			for (s = 0; s < maxSV1; s++) {
+				if (normalizedCounter[s] == -1) {
+					tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
+					symbolNext[s] = 1;
+				} else {
+					if (normalizedCounter[s] >= largeLimit)
+						DTableH.fastMode = 0;
+					symbolNext[s] = normalizedCounter[s];
+				}
+			}
+		}
+		memcpy(dt, &DTableH, sizeof(DTableH));
+	}
+
+	/* Spread symbols */
+	{
+		U32 const tableMask = tableSize - 1;
+		U32 const step = FSE_TABLESTEP(tableSize);
+		U32 s, position = 0;
+		for (s = 0; s < maxSV1; s++) {
+			int i;
+			for (i = 0; i < normalizedCounter[s]; i++) {
+				tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
+				position = (position + step) & tableMask;
+				while (position > highThreshold)
+					position = (position + step) & tableMask; /* lowprob area */
+			}
+		}
+		if (position != 0)
+			return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
+	}
+
+	/* Build Decoding table */
+	{
+		U32 u;
+		for (u = 0; u < tableSize; u++) {
+			FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
+			U16 nextState = symbolNext[symbol]++;
+			tableDecode[u].nbBits = (BYTE)(tableLog - BIT_highbit32((U32)nextState));
+			tableDecode[u].newState = (U16)((nextState << tableDecode[u].nbBits) - tableSize);
+		}
+	}
+
+	return 0;
+}
+
+/*-*******************************************************
+*  Decompression (Byte symbols)
+*********************************************************/
+size_t FSE_buildDTable_rle(FSE_DTable *dt, BYTE symbolValue)
+{
+	void *ptr = dt;
+	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
+	void *dPtr = dt + 1;
+	FSE_decode_t *const cell = (FSE_decode_t *)dPtr;
+
+	DTableH->tableLog = 0;
+	DTableH->fastMode = 0;
+
+	cell->newState = 0;
+	cell->symbol = symbolValue;
+	cell->nbBits = 0;
+
+	return 0;
+}
+
+size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits)
+{
+	void *ptr = dt;
+	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
+	void *dPtr = dt + 1;
+	FSE_decode_t *const dinfo = (FSE_decode_t *)dPtr;
+	const unsigned tableSize = 1 << nbBits;
+	const unsigned tableMask = tableSize - 1;
+	const unsigned maxSV1 = tableMask + 1;
+	unsigned s;
+
+	/* Sanity checks */
+	if (nbBits < 1)
+		return ERROR(GENERIC); /* min size */
+
+	/* Build Decoding Table */
+	DTableH->tableLog = (U16)nbBits;
+	DTableH->fastMode = 1;
+	for (s = 0; s < maxSV1; s++) {
+		dinfo[s].newState = 0;
+		dinfo[s].symbol = (BYTE)s;
+		dinfo[s].nbBits = (BYTE)nbBits;
+	}
+
+	return 0;
+}
+
+FORCE_INLINE size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt,
+						       const unsigned fast)
+{
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *op = ostart;
+	BYTE *const omax = op + maxDstSize;
+	BYTE *const olimit = omax - 3;
+
+	BIT_DStream_t bitD;
+	FSE_DState_t state1;
+	FSE_DState_t state2;
+
+	/* Init */
+	CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
+
+	FSE_initDState(&state1, &bitD, dt);
+	FSE_initDState(&state2, &bitD, dt);
+
+#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
+
+	/* 4 symbols per loop */
+	for (; (BIT_reloadDStream(&bitD) == BIT_DStream_unfinished) & (op < olimit); op += 4) {
+		op[0] = FSE_GETSYMBOL(&state1);
+
+		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+			BIT_reloadDStream(&bitD);
+
+		op[1] = FSE_GETSYMBOL(&state2);
+
+		if (FSE_MAX_TABLELOG * 4 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+		{
+			if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) {
+				op += 2;
+				break;
+			}
+		}
+
+		op[2] = FSE_GETSYMBOL(&state1);
+
+		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+			BIT_reloadDStream(&bitD);
+
+		op[3] = FSE_GETSYMBOL(&state2);
+	}
+
+	/* tail */
+	/* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
+	while (1) {
+		if (op > (omax - 2))
+			return ERROR(dstSize_tooSmall);
+		*op++ = FSE_GETSYMBOL(&state1);
+		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
+			*op++ = FSE_GETSYMBOL(&state2);
+			break;
+		}
+
+		if (op > (omax - 2))
+			return ERROR(dstSize_tooSmall);
+		*op++ = FSE_GETSYMBOL(&state2);
+		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
+			*op++ = FSE_GETSYMBOL(&state1);
+			break;
+		}
+	}
+
+	return op - ostart;
+}
+
+size_t FSE_decompress_usingDTable(void *dst, size_t originalSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt)
+{
+	const void *ptr = dt;
+	const FSE_DTableHeader *DTableH = (const FSE_DTableHeader *)ptr;
+	const U32 fastMode = DTableH->fastMode;
+
+	/* select fast mode (static) */
+	if (fastMode)
+		return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
+	return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
+}
+
+size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize)
+{
+	const BYTE *const istart = (const BYTE *)cSrc;
+	const BYTE *ip = istart;
+	unsigned tableLog;
+	unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
+	size_t NCountLength;
+
+	FSE_DTable *dt;
+	short *counting;
+	size_t spaceUsed32 = 0;
+
+	FSE_STATIC_ASSERT(sizeof(FSE_DTable) == sizeof(U32));
+
+	dt = (FSE_DTable *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += FSE_DTABLE_SIZE_U32(maxLog);
+	counting = (short *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1), sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* normal FSE decoding mode */
+	NCountLength = FSE_readNCount(counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
+	if (FSE_isError(NCountLength))
+		return NCountLength;
+	// if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong);   /* too small input size; supposed to be already checked in NCountLength, only remaining
+	// case : NCountLength==cSrcSize */
+	if (tableLog > maxLog)
+		return ERROR(tableLog_tooLarge);
+	ip += NCountLength;
+	cSrcSize -= NCountLength;
+
+	CHECK_F(FSE_buildDTable_wksp(dt, counting, maxSymbolValue, tableLog, workspace, workspaceSize));
+
+	return FSE_decompress_usingDTable(dst, dstCapacity, ip, cSrcSize, dt); /* always return, even if it is an error code */
+}