1 /* ******************************************************************
2 * Common functions of New Generation Entropy library
3 * Copyright (c) Yann Collet, Facebook, Inc.
4 *
5 * You can contact the author at :
6 * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c
8 *
9 * This source code is licensed under both the BSD-style license (found in the
10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
11 * in the COPYING file in the root directory of this source tree).
12 * You may select, at your option, one of the above-listed licenses.
13 ****************************************************************** */
14
15 /* *************************************
16 * Dependencies
17 ***************************************/
18 #include "mem.h"
19 #include "error_private.h" /* ERR_*, ERROR */
20 #define FSE_STATIC_LINKING_ONLY /* FSE_MIN_TABLELOG */
21 #include "fse.h"
22 #define HUF_STATIC_LINKING_ONLY /* HUF_TABLELOG_ABSOLUTEMAX */
23 #include "huf.h"
24
25
26 /*=== Version ===*/
FSE_versionNumber(void)27 unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
28
29
30 /*=== Error Management ===*/
FSE_isError(size_t code)31 unsigned FSE_isError(size_t code) { return ERR_isError(code); }
FSE_getErrorName(size_t code)32 const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }
33
HUF_isError(size_t code)34 unsigned HUF_isError(size_t code) { return ERR_isError(code); }
HUF_getErrorName(size_t code)35 const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }
36
37
38 /*-**************************************************************
39 * FSE NCount encoding-decoding
40 ****************************************************************/
FSE_ctz(U32 val)41 static U32 FSE_ctz(U32 val)
42 {
43 assert(val != 0);
44 {
45 # if defined(_MSC_VER) /* Visual */
46 if (val != 0) {
47 unsigned long r;
48 _BitScanForward(&r, val);
49 return (unsigned)r;
50 } else {
51 /* Should not reach this code path */
52 __assume(0);
53 }
54 # elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */
55 return __builtin_ctz(val);
56 # elif defined(__ICCARM__) /* IAR Intrinsic */
57 return __CTZ(val);
58 # else /* Software version */
59 U32 count = 0;
60 while ((val & 1) == 0) {
61 val >>= 1;
62 ++count;
63 }
64 return count;
65 # endif
66 }
67 }
68
69 FORCE_INLINE_TEMPLATE
FSE_readNCount_body(short * normalizedCounter,unsigned * maxSVPtr,unsigned * tableLogPtr,const void * headerBuffer,size_t hbSize)70 size_t FSE_readNCount_body(short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
71 const void* headerBuffer, size_t hbSize)
72 {
73 const BYTE* const istart = (const BYTE*) headerBuffer;
74 const BYTE* const iend = istart + hbSize;
75 const BYTE* ip = istart;
76 int nbBits;
77 int remaining;
78 int threshold;
79 U32 bitStream;
80 int bitCount;
81 unsigned charnum = 0;
82 unsigned const maxSV1 = *maxSVPtr + 1;
83 int previous0 = 0;
84
85 if (hbSize < 8) {
86 /* This function only works when hbSize >= 8 */
87 char buffer[8] = {0};
88 ZSTD_memcpy(buffer, headerBuffer, hbSize);
89 { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,
90 buffer, sizeof(buffer));
91 if (FSE_isError(countSize)) return countSize;
92 if (countSize > hbSize) return ERROR(corruption_detected);
93 return countSize;
94 } }
95 assert(hbSize >= 8);
96
97 /* init */
98 ZSTD_memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */
99 bitStream = MEM_readLE32(ip);
100 nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
101 if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
102 bitStream >>= 4;
103 bitCount = 4;
104 *tableLogPtr = nbBits;
105 remaining = (1<<nbBits)+1;
106 threshold = 1<<nbBits;
107 nbBits++;
108
109 for (;;) {
110 if (previous0) {
111 /* Count the number of repeats. Each time the
112 * 2-bit repeat code is 0b11 there is another
113 * repeat.
114 * Avoid UB by setting the high bit to 1.
115 */
116 int repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;
117 while (repeats >= 12) {
118 charnum += 3 * 12;
119 if (LIKELY(ip <= iend-7)) {
120 ip += 3;
121 } else {
122 bitCount -= (int)(8 * (iend - 7 - ip));
123 bitCount &= 31;
124 ip = iend - 4;
125 }
126 bitStream = MEM_readLE32(ip) >> bitCount;
127 repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;
128 }
129 charnum += 3 * repeats;
130 bitStream >>= 2 * repeats;
131 bitCount += 2 * repeats;
132
133 /* Add the final repeat which isn't 0b11. */
134 assert((bitStream & 3) < 3);
135 charnum += bitStream & 3;
136 bitCount += 2;
137
138 /* This is an error, but break and return an error
139 * at the end, because returning out of a loop makes
140 * it harder for the compiler to optimize.
141 */
142 if (charnum >= maxSV1) break;
143
144 /* We don't need to set the normalized count to 0
145 * because we already memset the whole buffer to 0.
146 */
147
148 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
149 assert((bitCount >> 3) <= 3); /* For first condition to work */
150 ip += bitCount>>3;
151 bitCount &= 7;
152 } else {
153 bitCount -= (int)(8 * (iend - 4 - ip));
154 bitCount &= 31;
155 ip = iend - 4;
156 }
157 bitStream = MEM_readLE32(ip) >> bitCount;
158 }
159 {
160 int const max = (2*threshold-1) - remaining;
161 int count;
162
163 if ((bitStream & (threshold-1)) < (U32)max) {
164 count = bitStream & (threshold-1);
165 bitCount += nbBits-1;
166 } else {
167 count = bitStream & (2*threshold-1);
168 if (count >= threshold) count -= max;
169 bitCount += nbBits;
170 }
171
172 count--; /* extra accuracy */
173 /* When it matters (small blocks), this is a
174 * predictable branch, because we don't use -1.
175 */
176 if (count >= 0) {
177 remaining -= count;
178 } else {
179 assert(count == -1);
180 remaining += count;
181 }
182 normalizedCounter[charnum++] = (short)count;
183 previous0 = !count;
184
185 assert(threshold > 1);
186 if (remaining < threshold) {
187 /* This branch can be folded into the
188 * threshold update condition because we
189 * know that threshold > 1.
190 */
191 if (remaining <= 1) break;
192 nbBits = BIT_highbit32(remaining) + 1;
193 threshold = 1 << (nbBits - 1);
194 }
195 if (charnum >= maxSV1) break;
196
197 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
198 ip += bitCount>>3;
199 bitCount &= 7;
200 } else {
201 bitCount -= (int)(8 * (iend - 4 - ip));
202 bitCount &= 31;
203 ip = iend - 4;
204 }
205 bitStream = MEM_readLE32(ip) >> bitCount;
206 } }
207 if (remaining != 1) return ERROR(corruption_detected);
208 /* Only possible when there are too many zeros. */
209 if (charnum > maxSV1) return ERROR(maxSymbolValue_tooSmall);
210 if (bitCount > 32) return ERROR(corruption_detected);
211 *maxSVPtr = charnum-1;
212
213 ip += (bitCount+7)>>3;
214 return ip-istart;
215 }
216
217 /* Avoids the FORCE_INLINE of the _body() function. */
FSE_readNCount_body_default(short * normalizedCounter,unsigned * maxSVPtr,unsigned * tableLogPtr,const void * headerBuffer,size_t hbSize)218 static size_t FSE_readNCount_body_default(
219 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
220 const void* headerBuffer, size_t hbSize)
221 {
222 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
223 }
224
225 #if DYNAMIC_BMI2
FSE_readNCount_body_bmi2(short * normalizedCounter,unsigned * maxSVPtr,unsigned * tableLogPtr,const void * headerBuffer,size_t hbSize)226 BMI2_TARGET_ATTRIBUTE static size_t FSE_readNCount_body_bmi2(
227 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
228 const void* headerBuffer, size_t hbSize)
229 {
230 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
231 }
232 #endif
233
FSE_readNCount_bmi2(short * normalizedCounter,unsigned * maxSVPtr,unsigned * tableLogPtr,const void * headerBuffer,size_t hbSize,int bmi2)234 size_t FSE_readNCount_bmi2(
235 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
236 const void* headerBuffer, size_t hbSize, int bmi2)
237 {
238 #if DYNAMIC_BMI2
239 if (bmi2) {
240 return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
241 }
242 #endif
243 (void)bmi2;
244 return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);
245 }
246
FSE_readNCount(short * normalizedCounter,unsigned * maxSVPtr,unsigned * tableLogPtr,const void * headerBuffer,size_t hbSize)247 size_t FSE_readNCount(
248 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
249 const void* headerBuffer, size_t hbSize)
250 {
251 return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0);
252 }
253
254
255 /*! HUF_readStats() :
256 Read compact Huffman tree, saved by HUF_writeCTable().
257 `huffWeight` is destination buffer.
258 `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
259 @return : size read from `src` , or an error Code .
260 Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
261 */
HUF_readStats(BYTE * huffWeight,size_t hwSize,U32 * rankStats,U32 * nbSymbolsPtr,U32 * tableLogPtr,const void * src,size_t srcSize)262 size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
263 U32* nbSymbolsPtr, U32* tableLogPtr,
264 const void* src, size_t srcSize)
265 {
266 U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
267 return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0);
268 }
269
270 FORCE_INLINE_TEMPLATE size_t
HUF_readStats_body(BYTE * huffWeight,size_t hwSize,U32 * rankStats,U32 * nbSymbolsPtr,U32 * tableLogPtr,const void * src,size_t srcSize,void * workSpace,size_t wkspSize,int bmi2)271 HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats,
272 U32* nbSymbolsPtr, U32* tableLogPtr,
273 const void* src, size_t srcSize,
274 void* workSpace, size_t wkspSize,
275 int bmi2)
276 {
277 U32 weightTotal;
278 const BYTE* ip = (const BYTE*) src;
279 size_t iSize;
280 size_t oSize;
281
282 if (!srcSize) return ERROR(srcSize_wrong);
283 iSize = ip[0];
284 /* ZSTD_memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */
285
286 if (iSize >= 128) { /* special header */
287 oSize = iSize - 127;
288 iSize = ((oSize+1)/2);
289 if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
290 if (oSize >= hwSize) return ERROR(corruption_detected);
291 ip += 1;
292 { U32 n;
293 for (n=0; n<oSize; n+=2) {
294 huffWeight[n] = ip[n/2] >> 4;
295 huffWeight[n+1] = ip[n/2] & 15;
296 } } }
297 else { /* header compressed with FSE (normal case) */
298 if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
299 /* max (hwSize-1) values decoded, as last one is implied */
300 oSize = FSE_decompress_wksp_bmi2(huffWeight, hwSize-1, ip+1, iSize, 6, workSpace, wkspSize, bmi2);
301 if (FSE_isError(oSize)) return oSize;
302 }
303
304 /* collect weight stats */
305 ZSTD_memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
306 weightTotal = 0;
307 { U32 n; for (n=0; n<oSize; n++) {
308 if (huffWeight[n] > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
309 rankStats[huffWeight[n]]++;
310 weightTotal += (1 << huffWeight[n]) >> 1;
311 } }
312 if (weightTotal == 0) return ERROR(corruption_detected);
313
314 /* get last non-null symbol weight (implied, total must be 2^n) */
315 { U32 const tableLog = BIT_highbit32(weightTotal) + 1;
316 if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
317 *tableLogPtr = tableLog;
318 /* determine last weight */
319 { U32 const total = 1 << tableLog;
320 U32 const rest = total - weightTotal;
321 U32 const verif = 1 << BIT_highbit32(rest);
322 U32 const lastWeight = BIT_highbit32(rest) + 1;
323 if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */
324 huffWeight[oSize] = (BYTE)lastWeight;
325 rankStats[lastWeight]++;
326 } }
327
328 /* check tree construction validity */
329 if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
330
331 /* results */
332 *nbSymbolsPtr = (U32)(oSize+1);
333 return iSize+1;
334 }
335
336 /* Avoids the FORCE_INLINE of the _body() function. */
HUF_readStats_body_default(BYTE * huffWeight,size_t hwSize,U32 * rankStats,U32 * nbSymbolsPtr,U32 * tableLogPtr,const void * src,size_t srcSize,void * workSpace,size_t wkspSize)337 static size_t HUF_readStats_body_default(BYTE* huffWeight, size_t hwSize, U32* rankStats,
338 U32* nbSymbolsPtr, U32* tableLogPtr,
339 const void* src, size_t srcSize,
340 void* workSpace, size_t wkspSize)
341 {
342 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0);
343 }
344
345 #if DYNAMIC_BMI2
HUF_readStats_body_bmi2(BYTE * huffWeight,size_t hwSize,U32 * rankStats,U32 * nbSymbolsPtr,U32 * tableLogPtr,const void * src,size_t srcSize,void * workSpace,size_t wkspSize)346 static BMI2_TARGET_ATTRIBUTE size_t HUF_readStats_body_bmi2(BYTE* huffWeight, size_t hwSize, U32* rankStats,
347 U32* nbSymbolsPtr, U32* tableLogPtr,
348 const void* src, size_t srcSize,
349 void* workSpace, size_t wkspSize)
350 {
351 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1);
352 }
353 #endif
354
HUF_readStats_wksp(BYTE * huffWeight,size_t hwSize,U32 * rankStats,U32 * nbSymbolsPtr,U32 * tableLogPtr,const void * src,size_t srcSize,void * workSpace,size_t wkspSize,int bmi2)355 size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats,
356 U32* nbSymbolsPtr, U32* tableLogPtr,
357 const void* src, size_t srcSize,
358 void* workSpace, size_t wkspSize,
359 int bmi2)
360 {
361 #if DYNAMIC_BMI2
362 if (bmi2) {
363 return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
364 }
365 #endif
366 (void)bmi2;
367 return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
368 }
369