Line data Source code
1 : /*
2 : * Copyright (c) 2008-2012 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 0 : ispower2(mpd_size_t n)
40 : {
41 0 : 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 0 : mpd_bsr(mpd_size_t a)
108 : {
109 : mpd_size_t retval;
110 :
111 0 : __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 0 : return (int)retval;
123 : }
124 :
125 : /*
126 : * Bit scan forward. Assumptions: a != 0.
127 : */
128 : static inline int
129 0 : mpd_bsf(mpd_size_t a)
130 : {
131 : mpd_size_t retval;
132 :
133 0 : __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 0 : 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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