intmath.hh revision 1642 
1/*
2 * Copyright (c) 2001, 2003 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef __INTMATH_HH__
30#define __INTMATH_HH__
31
32#include <assert.h>
33
34#include "sim/host.hh"
35
36// Returns the prime number one less than n.
37int PrevPrime(int n);
38
39// Determine if a number is prime
40template <class T>
41inline bool
42IsPrime(T n)
43{
44    T i;
45
46    if (n == 2 || n == 3)
47        return true;
48
49    // Don't try every odd number to prove if it is a prime.
50    // Toggle between every 2nd and 4th number.
51    // (This is because every 6th odd number is divisible by 3.)
52    for (i = 5; i*i <= n; i += 6) {
53        if (((n % i) == 0 ) || ((n % (i + 2)) == 0) ) {
54            return false;
55        }
56    }
57
58    return true;
59}
60
61template <class T>
62inline T
63LeastSigBit(T n)
64{
65    return n & ~(n - 1);
66}
67
68template <class T>
69inline bool
70IsPowerOf2(T n)
71{
72    return n != 0 && LeastSigBit(n) == n;
73}
74
75inline int
76FloorLog2(unsigned x)
77{
78    assert(x > 0);
79
80    int y = 0;
81
82    if (x & 0xffff0000) { y += 16; x >>= 16; }
83    if (x & 0x0000ff00) { y +=  8; x >>=  8; }
84    if (x & 0x000000f0) { y +=  4; x >>=  4; }
85    if (x & 0x0000000c) { y +=  2; x >>=  2; }
86    if (x & 0x00000002) { y +=  1; }
87
88    return y;
89}
90
91inline int
92FloorLog2(unsigned long x)
93{
94    assert(x > 0);
95
96    int y = 0;
97
98#if defined(__LP64__)
99    if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
100#endif
101    if (x & 0xffff0000) { y += 16; x >>= 16; }
102    if (x & 0x0000ff00) { y +=  8; x >>=  8; }
103    if (x & 0x000000f0) { y +=  4; x >>=  4; }
104    if (x & 0x0000000c) { y +=  2; x >>=  2; }
105    if (x & 0x00000002) { y +=  1; }
106
107    return y;
108}
109
110inline int
111FloorLog2(unsigned long long x)
112{
113    assert(x > 0);
114
115    int y = 0;
116
117    if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
118    if (x & ULL(0x00000000ffff0000)) { y += 16; x >>= 16; }
119    if (x & ULL(0x000000000000ff00)) { y +=  8; x >>=  8; }
120    if (x & ULL(0x00000000000000f0)) { y +=  4; x >>=  4; }
121    if (x & ULL(0x000000000000000c)) { y +=  2; x >>=  2; }
122    if (x & ULL(0x0000000000000002)) { y +=  1; }
123
124    return y;
125}
126
127inline int
128FloorLog2(int x)
129{
130    assert(x > 0);
131    return FloorLog2((unsigned)x);
132}
133
134inline int
135FloorLog2(long x)
136{
137    assert(x > 0);
138    return FloorLog2((unsigned long)x);
139}
140
141inline int
142FloorLog2(long long x)
143{
144    assert(x > 0);
145    return FloorLog2((unsigned long long)x);
146}
147
148#if defined(__APPLE__)
149inline int
150FloorLog2(size_t x)
151{
152    assert(x > 0);
153    assert(sizeof(size_t) == 4 || sizeof(size_t) == 8);
154
155    // It's my hope that this is optimized away?
156    if (sizeof(size_t) == 4)
157        return FloorLog2((uint32_t)x);
158     else if (sizeof(size_t) == 8)
159        return FloorLog2((uint64_t)x);
160
161}
162#endif
163
164template <class T>
165inline int
166CeilLog2(T n)
167{
168    if (n == 1)
169        return 0;
170
171    return FloorLog2(n - (T)1) + 1;
172}
173
174template <class T>
175inline T
176FloorPow2(T n)
177{
178    return (T)1 << FloorLog2(n);
179}
180
181template <class T>
182inline T
183CeilPow2(T n)
184{
185    return (T)1 << CeilLog2(n);
186}
187
188template <class T>
189inline T
190DivCeil(T a, T b)
191{
192    return (a + b - 1) / b;
193}
194
195template <class T>
196inline T
197RoundUp(T val, T align)
198{
199    T mask = align - 1;
200    return (val + mask) & ~mask;
201}
202
203template <class T>
204inline T
205RoundDown(T val, T align)
206{
207    T mask = align - 1;
208    return val & ~mask;
209}
210
211inline bool
212IsHex(char c)
213{
214    return c >= '0' && c <= '9' ||
215        c >= 'A' && c <= 'F' ||
216        c >= 'a' && c <= 'f';
217}
218
219inline bool
220IsOct(char c)
221{
222    return c >= '0' && c <= '7';
223}
224
225inline bool
226IsDec(char c)
227{
228    return c >= '0' && c <= '9';
229}
230
231inline int
232Hex2Int(char c)
233{
234  if (c >= '0' && c <= '9')
235    return (c - '0');
236
237  if (c >= 'A' && c <= 'F')
238    return (c - 'A') + 10;
239
240  if (c >= 'a' && c <= 'f')
241    return (c - 'a') + 10;
242
243  return 0;
244}
245
246#endif // __INTMATH_HH__
247