1 /* ******************************************* 1
2 * hist : Histogram functions
3 * part of Finite State Entropy project
4 * Copyright (c) Yann Collet, Facebook, Inc.
5 *
6 * You can contact the author at :
7 * - FSE source repository : https://github.c
8 * - Public forum : https://groups.google.com
9 *
10 * This source code is licensed under both the
11 * LICENSE file in the root directory of this
12 * in the COPYING file in the root directory o
13 * You may select, at your option, one of the
14 **********************************************
15
16 /* --- dependencies --- */
17 #include "../common/mem.h" /* U32,
18 #include "../common/debug.h" /* asse
19 #include "../common/error_private.h" /* ERRO
20 #include "hist.h"
21
22
23 /* --- Error management --- */
24 unsigned HIST_isError(size_t code) { return ER
25
26 /*-*******************************************
27 * Histogram functions
28 *********************************************
29 unsigned HIST_count_simple(unsigned* count, un
30 const void* src, si
31 {
32 const BYTE* ip = (const BYTE*)src;
33 const BYTE* const end = ip + srcSize;
34 unsigned maxSymbolValue = *maxSymbolValueP
35 unsigned largestCount=0;
36
37 ZSTD_memset(count, 0, (maxSymbolValue+1) *
38 if (srcSize==0) { *maxSymbolValuePtr = 0;
39
40 while (ip<end) {
41 assert(*ip <= maxSymbolValue);
42 count[*ip++]++;
43 }
44
45 while (!count[maxSymbolValue]) maxSymbolVa
46 *maxSymbolValuePtr = maxSymbolValue;
47
48 { U32 s;
49 for (s=0; s<=maxSymbolValue; s++)
50 if (count[s] > largestCount) large
51 }
52
53 return largestCount;
54 }
55
56 typedef enum { trustInput, checkMaxSymbolValue
57
58 /* HIST_count_parallel_wksp() :
59 * store histogram into 4 intermediate tables,
60 * this design makes better use of OoO cpus,
61 * and is noticeably faster when some values a
62 * But it needs some additional workspace for
63 * `workSpace` must be a U32 table of size >=
64 * @return : largest histogram frequency,
65 * or an error code (notably when hi
66 static size_t HIST_count_parallel_wksp(
67 unsigned* coun
68 const void* so
69 HIST_checkInpu
70 U32* const wor
71 {
72 const BYTE* ip = (const BYTE*)source;
73 const BYTE* const iend = ip+sourceSize;
74 size_t const countSize = (*maxSymbolValueP
75 unsigned max=0;
76 U32* const Counting1 = workSpace;
77 U32* const Counting2 = Counting1 + 256;
78 U32* const Counting3 = Counting2 + 256;
79 U32* const Counting4 = Counting3 + 256;
80
81 /* safety checks */
82 assert(*maxSymbolValuePtr <= 255);
83 if (!sourceSize) {
84 ZSTD_memset(count, 0, countSize);
85 *maxSymbolValuePtr = 0;
86 return 0;
87 }
88 ZSTD_memset(workSpace, 0, 4*256*sizeof(uns
89
90 /* by stripes of 16 bytes */
91 { U32 cached = MEM_read32(ip); ip += 4;
92 while (ip < iend-15) {
93 U32 c = cached; cached = MEM_read3
94 Counting1[(BYTE) c ]++;
95 Counting2[(BYTE)(c>>8) ]++;
96 Counting3[(BYTE)(c>>16)]++;
97 Counting4[ c>>24 ]++;
98 c = cached; cached = MEM_read32(ip
99 Counting1[(BYTE) c ]++;
100 Counting2[(BYTE)(c>>8) ]++;
101 Counting3[(BYTE)(c>>16)]++;
102 Counting4[ c>>24 ]++;
103 c = cached; cached = MEM_read32(ip
104 Counting1[(BYTE) c ]++;
105 Counting2[(BYTE)(c>>8) ]++;
106 Counting3[(BYTE)(c>>16)]++;
107 Counting4[ c>>24 ]++;
108 c = cached; cached = MEM_read32(ip
109 Counting1[(BYTE) c ]++;
110 Counting2[(BYTE)(c>>8) ]++;
111 Counting3[(BYTE)(c>>16)]++;
112 Counting4[ c>>24 ]++;
113 }
114 ip-=4;
115 }
116
117 /* finish last symbols */
118 while (ip<iend) Counting1[*ip++]++;
119
120 { U32 s;
121 for (s=0; s<256; s++) {
122 Counting1[s] += Counting2[s] + Cou
123 if (Counting1[s] > max) max = Coun
124 } }
125
126 { unsigned maxSymbolValue = 255;
127 while (!Counting1[maxSymbolValue]) max
128 if (check && maxSymbolValue > *maxSymb
129 *maxSymbolValuePtr = maxSymbolValue;
130 ZSTD_memmove(count, Counting1, countSi
131 }
132 return (size_t)max;
133 }
134
135 /* HIST_countFast_wksp() :
136 * Same as HIST_countFast(), but using an exte
137 * `workSpace` is a writable buffer which must
138 * `workSpaceSize` must be >= HIST_WKSP_SIZE
139 */
140 size_t HIST_countFast_wksp(unsigned* count, un
141 const void* source,
142 void* workSpace, siz
143 {
144 if (sourceSize < 1500) /* heuristic thresh
145 return HIST_count_simple(count, maxSym
146 if ((size_t)workSpace & 3) return ERROR(GE
147 if (workSpaceSize < HIST_WKSP_SIZE) return
148 return HIST_count_parallel_wksp(count, max
149 }
150
151 /* HIST_count_wksp() :
152 * Same as HIST_count(), but using an external
153 * `workSpace` size must be table of >= HIST_W
154 size_t HIST_count_wksp(unsigned* count, unsign
155 const void* source, siz
156 void* workSpace, size_t
157 {
158 if ((size_t)workSpace & 3) return ERROR(GE
159 if (workSpaceSize < HIST_WKSP_SIZE) return
160 if (*maxSymbolValuePtr < 255)
161 return HIST_count_parallel_wksp(count,
162 *maxSymbolValuePtr = 255;
163 return HIST_countFast_wksp(count, maxSymbo
164 }
165
166
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