intmath.hh revision 100 
1/*
2 * Copyright (c) 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(uint32_t 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(uint64_t x)
93{
94    assert(x > 0);
95
96    int y = 0;
97
98    if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
99    if (x & ULL(0x00000000ffff0000)) { y += 16; x >>= 16; }
100    if (x & ULL(0x000000000000ff00)) { y +=  8; x >>=  8; }
101    if (x & ULL(0x00000000000000f0)) { y +=  4; x >>=  4; }
102    if (x & ULL(0x000000000000000c)) { y +=  2; x >>=  2; }
103    if (x & ULL(0x0000000000000002)) { y +=  1; }
104
105    return y;
106}
107
108inline int
109FloorLog2(int32_t x)
110{
111    assert(x > 0);
112    return FloorLog2(x);
113}
114
115inline int
116FloorLog2(int64_t x)
117{
118    assert(x > 0);
119    return FloorLog2(x);
120}
121
122template <class T>
123inline int
124CeilLog2(T n)
125{
126    if (n == 1)
127        return 0;
128
129    return FloorLog2(n - (T)1) + 1;
130}
131
132template <class T>
133inline T
134FloorPow2(T n)
135{
136    return (T)1 << FloorLog2(n);
137}
138
139template <class T>
140inline T
141CeilPow2(T n)
142{
143    return (T)1 << CeilLog2(n);
144}
145
146template <class T>
147inline T
148DivCeil(T a, T b)
149{
150    return (a + b - 1) / b;
151}
152
153template <class T>
154inline T
155RoundUp(T val, T align)
156{
157    T mask = align - 1;
158    return (val + mask) & ~mask;
159}
160
161template <class T>
162inline T
163RoundDown(T val, T align)
164{
165    T mask = align - 1;
166    return val & ~mask;
167}
168
169inline bool
170IsHex(char c)
171{
172    return c >= '0' && c <= '9' ||
173        c >= 'A' && c <= 'F' ||
174        c >= 'a' && c <= 'f';
175}
176
177inline bool
178IsOct(char c)
179{
180    return c >= '0' && c <= '7';
181}
182
183inline bool
184IsDec(char c)
185{
186    return c >= '0' && c <= '9';
187}
188
189inline int
190Hex2Int(char c)
191{
192  if (c >= '0' && c <= '9')
193    return (c - '0');
194
195  if(c >= 'A' && c <= 'F')
196    return (c - 'A') + 10;
197
198  if (c >= 'a' && c <= 'f')
199    return (c - 'a') + 10;
200
201  return 0;
202}
203
204#endif // __INTMATH_HH__
205