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Side by Side Diff: Modules/_decimal/libmpdec/bits.h

Issue 7652: Merge C version of decimal into py3k.
Patch Set: Created 7 years, 3 months ago
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1 /*
2 * Copyright (c) 2008-2010 Stefan Krah. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28
29 #ifndef BITS_H
30 #define BITS_H
31
32
33 #include "mpdecimal.h"
34 #include <stdio.h>
35
36
37 /* Check if n is a power of 2. */
38 static inline int
39 ispower2(mpd_size_t n)
40 {
41 return n != 0 && (n & (n-1)) == 0;
42 }
43
44 #if defined(ANSI)
45 /*
46 * Return the most significant bit position of n from 0 to 31 (63).
47 * Assumptions: n != 0.
48 */
49 static inline int
50 mpd_bsr(mpd_size_t n)
51 {
52 int pos = 0;
53 mpd_size_t tmp;
54
55 #ifdef CONFIG_64
56 tmp = n >> 32;
57 if (tmp != 0) { n = tmp; pos += 32; }
58 #endif
59 tmp = n >> 16;
60 if (tmp != 0) { n = tmp; pos += 16; }
61 tmp = n >> 8;
62 if (tmp != 0) { n = tmp; pos += 8; }
63 tmp = n >> 4;
64 if (tmp != 0) { n = tmp; pos += 4; }
65 tmp = n >> 2;
66 if (tmp != 0) { n = tmp; pos += 2; }
67 tmp = n >> 1;
68 if (tmp != 0) { n = tmp; pos += 1; }
69
70 return pos + (int)n - 1;
71 }
72
73 /*
74 * Return the least significant bit position of n from 0 to 31 (63).
75 * Assumptions: n != 0.
76 */
77 static inline int
78 mpd_bsf(mpd_size_t n)
79 {
80 int pos;
81
82 #ifdef CONFIG_64
83 pos = 63;
84 if (n & 0x00000000FFFFFFFFULL) { pos -= 32; } else { n >>= 32; }
85 if (n & 0x000000000000FFFFULL) { pos -= 16; } else { n >>= 16; }
86 if (n & 0x00000000000000FFULL) { pos -= 8; } else { n >>= 8; }
87 if (n & 0x000000000000000FULL) { pos -= 4; } else { n >>= 4; }
88 if (n & 0x0000000000000003ULL) { pos -= 2; } else { n >>= 2; }
89 if (n & 0x0000000000000001ULL) { pos -= 1; }
90 #else
91 pos = 31;
92 if (n & 0x000000000000FFFFUL) { pos -= 16; } else { n >>= 16; }
93 if (n & 0x00000000000000FFUL) { pos -= 8; } else { n >>= 8; }
94 if (n & 0x000000000000000FUL) { pos -= 4; } else { n >>= 4; }
95 if (n & 0x0000000000000003UL) { pos -= 2; } else { n >>= 2; }
96 if (n & 0x0000000000000001UL) { pos -= 1; }
97 #endif
98 return pos;
99 }
100 /* END ANSI */
101
102 #elif defined(ASM)
103 /*
104 * Bit scan reverse. Assumptions: a != 0.
105 */
106 static inline int
107 mpd_bsr(mpd_size_t a)
108 {
109 mpd_size_t retval;
110
111 __asm__ (
112 #ifdef CONFIG_64
113 "bsrq %1, %0\n\t"
114 #else
115 "bsr %1, %0\n\t"
116 #endif
117 :"=r" (retval)
118 :"r" (a)
119 :"cc"
120 );
121
122 return (int)retval;
123 }
124
125 /*
126 * Bit scan forward. Assumptions: a != 0.
127 */
128 static inline int
129 mpd_bsf(mpd_size_t a)
130 {
131 mpd_size_t retval;
132
133 __asm__ (
134 #ifdef CONFIG_64
135 "bsfq %1, %0\n\t"
136 #else
137 "bsf %1, %0\n\t"
138 #endif
139 :"=r" (retval)
140 :"r" (a)
141 :"cc"
142 );
143
144 return (int)retval;
145 }
146 /* END ASM */
147
148 #elif defined(MASM)
149 #include <intrin.h>
150 /*
151 * Bit scan reverse. Assumptions: a != 0.
152 */
153 static inline int __cdecl
154 mpd_bsr(mpd_size_t a)
155 {
156 unsigned long retval;
157
158 #ifdef CONFIG_64
159 _BitScanReverse64(&retval, a);
160 #else
161 _BitScanReverse(&retval, a);
162 #endif
163
164 return (int)retval;
165 }
166
167 /*
168 * Bit scan forward. Assumptions: a != 0.
169 */
170 static inline int __cdecl
171 mpd_bsf(mpd_size_t a)
172 {
173 unsigned long retval;
174
175 #ifdef CONFIG_64
176 _BitScanForward64(&retval, a);
177 #else
178 _BitScanForward(&retval, a);
179 #endif
180
181 return (int)retval;
182 }
183 /* END MASM (_MSC_VER) */
184 #else
185 #error "missing preprocessor definitions"
186 #endif /* BSR/BSF */
187
188
189 #endif /* BITS_H */
190
191
192
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