1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
/*
* Copyright (c) 2008-2020 Stefan Krah. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef LIBMPDEC_BITS_H_
#define LIBMPDEC_BITS_H_
#include "mpdecimal.h"
/* Check if n is a power of 2. */
static inline int
ispower2(mpd_size_t n)
{
return n != 0 && (n & (n-1)) == 0;
}
#if defined(ANSI)
/*
* Return the most significant bit position of n from 0 to 31 (63).
* Assumptions: n != 0.
*/
static inline int
mpd_bsr(mpd_size_t n)
{
int pos = 0;
mpd_size_t tmp;
#ifdef CONFIG_64
tmp = n >> 32;
if (tmp != 0) { n = tmp; pos += 32; }
#endif
tmp = n >> 16;
if (tmp != 0) { n = tmp; pos += 16; }
tmp = n >> 8;
if (tmp != 0) { n = tmp; pos += 8; }
tmp = n >> 4;
if (tmp != 0) { n = tmp; pos += 4; }
tmp = n >> 2;
if (tmp != 0) { n = tmp; pos += 2; }
tmp = n >> 1;
if (tmp != 0) { n = tmp; pos += 1; }
return pos + (int)n - 1;
}
/*
* Return the least significant bit position of n from 0 to 31 (63).
* Assumptions: n != 0.
*/
static inline int
mpd_bsf(mpd_size_t n)
{
int pos;
#ifdef CONFIG_64
pos = 63;
if (n & 0x00000000FFFFFFFFULL) { pos -= 32; } else { n >>= 32; }
if (n & 0x000000000000FFFFULL) { pos -= 16; } else { n >>= 16; }
if (n & 0x00000000000000FFULL) { pos -= 8; } else { n >>= 8; }
if (n & 0x000000000000000FULL) { pos -= 4; } else { n >>= 4; }
if (n & 0x0000000000000003ULL) { pos -= 2; } else { n >>= 2; }
if (n & 0x0000000000000001ULL) { pos -= 1; }
#else
pos = 31;
if (n & 0x000000000000FFFFUL) { pos -= 16; } else { n >>= 16; }
if (n & 0x00000000000000FFUL) { pos -= 8; } else { n >>= 8; }
if (n & 0x000000000000000FUL) { pos -= 4; } else { n >>= 4; }
if (n & 0x0000000000000003UL) { pos -= 2; } else { n >>= 2; }
if (n & 0x0000000000000001UL) { pos -= 1; }
#endif
return pos;
}
/* END ANSI */
#elif defined(ASM)
/*
* Bit scan reverse. Assumptions: a != 0.
*/
static inline int
mpd_bsr(mpd_size_t a)
{
mpd_size_t retval;
__asm__ (
#ifdef CONFIG_64
"bsrq %1, %0\n\t"
#else
"bsr %1, %0\n\t"
#endif
:"=r" (retval)
:"r" (a)
:"cc"
);
return (int)retval;
}
/*
* Bit scan forward. Assumptions: a != 0.
*/
static inline int
mpd_bsf(mpd_size_t a)
{
mpd_size_t retval;
__asm__ (
#ifdef CONFIG_64
"bsfq %1, %0\n\t"
#else
"bsf %1, %0\n\t"
#endif
:"=r" (retval)
:"r" (a)
:"cc"
);
return (int)retval;
}
/* END ASM */
#elif defined(MASM)
#include <intrin.h>
/*
* Bit scan reverse. Assumptions: a != 0.
*/
static inline int __cdecl
mpd_bsr(mpd_size_t a)
{
unsigned long retval;
#ifdef CONFIG_64
_BitScanReverse64(&retval, a);
#else
_BitScanReverse(&retval, a);
#endif
return (int)retval;
}
/*
* Bit scan forward. Assumptions: a != 0.
*/
static inline int __cdecl
mpd_bsf(mpd_size_t a)
{
unsigned long retval;
#ifdef CONFIG_64
_BitScanForward64(&retval, a);
#else
_BitScanForward(&retval, a);
#endif
return (int)retval;
}
/* END MASM (_MSC_VER) */
#else
#error "missing preprocessor definitions"
#endif /* BSR/BSF */
#endif /* LIBMPDEC_BITS_H_ */
|
