1/*
2 * FSE : Finite State Entropy decoder
3 * Copyright (C) 2013-2015, Yann Collet.
4 *
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
9 * met:
10 *
11 *   * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 *   * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * This program is free software; you can redistribute it and/or modify it under
31 * the terms of the GNU General Public License version 2 as published by the
32 * Free Software Foundation. This program is dual-licensed; you may select
33 * either version 2 of the GNU General Public License ("GPL") or BSD license
34 * ("BSD").
35 *
36 * You can contact the author at :
37 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
38 */
39
40/* **************************************************************
41*  Compiler specifics
42****************************************************************/
43#define FORCE_INLINE static __always_inline
44
45/* **************************************************************
46*  Includes
47****************************************************************/
48#include "bitstream.h"
49#include "fse.h"
50#include "zstd_internal.h"
51#include <linux/compiler.h>
52#include <linux/kernel.h>
53#include <linux/string.h> /* memcpy, memset */
54
55/* **************************************************************
56*  Error Management
57****************************************************************/
58#define FSE_isError ERR_isError
59#define FSE_STATIC_ASSERT(c)                                   \
60	{                                                      \
61		enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
62	} /* use only *after* variable declarations */
63
64/* **************************************************************
65*  Templates
66****************************************************************/
67/*
68  designed to be included
69  for type-specific functions (template emulation in C)
70  Objective is to write these functions only once, for improved maintenance
71*/
72
73/* safety checks */
74#ifndef FSE_FUNCTION_EXTENSION
75#error "FSE_FUNCTION_EXTENSION must be defined"
76#endif
77#ifndef FSE_FUNCTION_TYPE
78#error "FSE_FUNCTION_TYPE must be defined"
79#endif
80
81/* Function names */
82#define FSE_CAT(X, Y) X##Y
83#define FSE_FUNCTION_NAME(X, Y) FSE_CAT(X, Y)
84#define FSE_TYPE_NAME(X, Y) FSE_CAT(X, Y)
85
86/* Function templates */
87
88size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)
89{
90	void *const tdPtr = dt + 1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
91	FSE_DECODE_TYPE *const tableDecode = (FSE_DECODE_TYPE *)(tdPtr);
92	U16 *symbolNext = (U16 *)workspace;
93
94	U32 const maxSV1 = maxSymbolValue + 1;
95	U32 const tableSize = 1 << tableLog;
96	U32 highThreshold = tableSize - 1;
97
98	/* Sanity Checks */
99	if (workspaceSize < sizeof(U16) * (FSE_MAX_SYMBOL_VALUE + 1))
100		return ERROR(tableLog_tooLarge);
101	if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE)
102		return ERROR(maxSymbolValue_tooLarge);
103	if (tableLog > FSE_MAX_TABLELOG)
104		return ERROR(tableLog_tooLarge);
105
106	/* Init, lay down lowprob symbols */
107	{
108		FSE_DTableHeader DTableH;
109		DTableH.tableLog = (U16)tableLog;
110		DTableH.fastMode = 1;
111		{
112			S16 const largeLimit = (S16)(1 << (tableLog - 1));
113			U32 s;
114			for (s = 0; s < maxSV1; s++) {
115				if (normalizedCounter[s] == -1) {
116					tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
117					symbolNext[s] = 1;
118				} else {
119					if (normalizedCounter[s] >= largeLimit)
120						DTableH.fastMode = 0;
121					symbolNext[s] = normalizedCounter[s];
122				}
123			}
124		}
125		memcpy(dt, &DTableH, sizeof(DTableH));
126	}
127
128	/* Spread symbols */
129	{
130		U32 const tableMask = tableSize - 1;
131		U32 const step = FSE_TABLESTEP(tableSize);
132		U32 s, position = 0;
133		for (s = 0; s < maxSV1; s++) {
134			int i;
135			for (i = 0; i < normalizedCounter[s]; i++) {
136				tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
137				position = (position + step) & tableMask;
138				while (position > highThreshold)
139					position = (position + step) & tableMask; /* lowprob area */
140			}
141		}
142		if (position != 0)
143			return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
144	}
145
146	/* Build Decoding table */
147	{
148		U32 u;
149		for (u = 0; u < tableSize; u++) {
150			FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
151			U16 nextState = symbolNext[symbol]++;
152			tableDecode[u].nbBits = (BYTE)(tableLog - BIT_highbit32((U32)nextState));
153			tableDecode[u].newState = (U16)((nextState << tableDecode[u].nbBits) - tableSize);
154		}
155	}
156
157	return 0;
158}
159
160/*-*******************************************************
161*  Decompression (Byte symbols)
162*********************************************************/
163size_t FSE_buildDTable_rle(FSE_DTable *dt, BYTE symbolValue)
164{
165	void *ptr = dt;
166	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
167	void *dPtr = dt + 1;
168	FSE_decode_t *const cell = (FSE_decode_t *)dPtr;
169
170	DTableH->tableLog = 0;
171	DTableH->fastMode = 0;
172
173	cell->newState = 0;
174	cell->symbol = symbolValue;
175	cell->nbBits = 0;
176
177	return 0;
178}
179
180size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits)
181{
182	void *ptr = dt;
183	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
184	void *dPtr = dt + 1;
185	FSE_decode_t *const dinfo = (FSE_decode_t *)dPtr;
186	const unsigned tableSize = 1 << nbBits;
187	const unsigned tableMask = tableSize - 1;
188	const unsigned maxSV1 = tableMask + 1;
189	unsigned s;
190
191	/* Sanity checks */
192	if (nbBits < 1)
193		return ERROR(GENERIC); /* min size */
194
195	/* Build Decoding Table */
196	DTableH->tableLog = (U16)nbBits;
197	DTableH->fastMode = 1;
198	for (s = 0; s < maxSV1; s++) {
199		dinfo[s].newState = 0;
200		dinfo[s].symbol = (BYTE)s;
201		dinfo[s].nbBits = (BYTE)nbBits;
202	}
203
204	return 0;
205}
206
207FORCE_INLINE size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt,
208						       const unsigned fast)
209{
210	BYTE *const ostart = (BYTE *)dst;
211	BYTE *op = ostart;
212	BYTE *const omax = op + maxDstSize;
213	BYTE *const olimit = omax - 3;
214
215	BIT_DStream_t bitD;
216	FSE_DState_t state1;
217	FSE_DState_t state2;
218
219	/* Init */
220	CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
221
222	FSE_initDState(&state1, &bitD, dt);
223	FSE_initDState(&state2, &bitD, dt);
224
225#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
226
227	/* 4 symbols per loop */
228	for (; (BIT_reloadDStream(&bitD) == BIT_DStream_unfinished) & (op < olimit); op += 4) {
229		op[0] = FSE_GETSYMBOL(&state1);
230
231		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
232			BIT_reloadDStream(&bitD);
233
234		op[1] = FSE_GETSYMBOL(&state2);
235
236		if (FSE_MAX_TABLELOG * 4 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
237		{
238			if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) {
239				op += 2;
240				break;
241			}
242		}
243
244		op[2] = FSE_GETSYMBOL(&state1);
245
246		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
247			BIT_reloadDStream(&bitD);
248
249		op[3] = FSE_GETSYMBOL(&state2);
250	}
251
252	/* tail */
253	/* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
254	while (1) {
255		if (op > (omax - 2))
256			return ERROR(dstSize_tooSmall);
257		*op++ = FSE_GETSYMBOL(&state1);
258		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
259			*op++ = FSE_GETSYMBOL(&state2);
260			break;
261		}
262
263		if (op > (omax - 2))
264			return ERROR(dstSize_tooSmall);
265		*op++ = FSE_GETSYMBOL(&state2);
266		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
267			*op++ = FSE_GETSYMBOL(&state1);
268			break;
269		}
270	}
271
272	return op - ostart;
273}
274
275size_t FSE_decompress_usingDTable(void *dst, size_t originalSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt)
276{
277	const void *ptr = dt;
278	const FSE_DTableHeader *DTableH = (const FSE_DTableHeader *)ptr;
279	const U32 fastMode = DTableH->fastMode;
280
281	/* select fast mode (static) */
282	if (fastMode)
283		return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
284	return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
285}
286
287size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize)
288{
289	const BYTE *const istart = (const BYTE *)cSrc;
290	const BYTE *ip = istart;
291	unsigned tableLog;
292	unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
293	size_t NCountLength;
294
295	FSE_DTable *dt;
296	short *counting;
297	size_t spaceUsed32 = 0;
298
299	FSE_STATIC_ASSERT(sizeof(FSE_DTable) == sizeof(U32));
300
301	dt = (FSE_DTable *)((U32 *)workspace + spaceUsed32);
302	spaceUsed32 += FSE_DTABLE_SIZE_U32(maxLog);
303	counting = (short *)((U32 *)workspace + spaceUsed32);
304	spaceUsed32 += ALIGN(sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1), sizeof(U32)) >> 2;
305
306	if ((spaceUsed32 << 2) > workspaceSize)
307		return ERROR(tableLog_tooLarge);
308	workspace = (U32 *)workspace + spaceUsed32;
309	workspaceSize -= (spaceUsed32 << 2);
310
311	/* normal FSE decoding mode */
312	NCountLength = FSE_readNCount(counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
313	if (FSE_isError(NCountLength))
314		return NCountLength;
315	// if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong);   /* too small input size; supposed to be already checked in NCountLength, only remaining
316	// case : NCountLength==cSrcSize */
317	if (tableLog > maxLog)
318		return ERROR(tableLog_tooLarge);
319	ip += NCountLength;
320	cSrcSize -= NCountLength;
321
322	CHECK_F(FSE_buildDTable_wksp(dt, counting, maxSymbolValue, tableLog, workspace, workspaceSize));
323
324	return FSE_decompress_usingDTable(dst, dstCapacity, ip, cSrcSize, dt); /* always return, even if it is an error code */
325}
326