src/base/intmath.hh

   1 /*
   2  * Copyright (c) 2001, 2003-2005 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  * Authors: Nathan Binkert
  29  */
  30
  31 #ifndef __BASE_INTMATH_HH__
  32 #define __BASE_INTMATH_HH__
  33
  34 #include <cassert>
  35
  36 #include "base/types.hh"
  37
  38 // Returns the prime number one less than n.
  39 int prevPrime(int n);
  40
  41 // Determine if a number is prime
  42 template <class T>
  43 inline bool
  44 isPrime(T n)
  45 {
  46     T i;
  47
  48     if (n == 2 || n == 3)
  49         return true;
  50
  51     // Don't try every odd number to prove if it is a prime.
  52     // Toggle between every 2nd and 4th number.
  53     // (This is because every 6th odd number is divisible by 3.)
  54     for (i = 5; i*i <= n; i += 6) {
  55         if (((n % i) == 0 ) || ((n % (i + 2)) == 0) ) {
  56             return false;
  57         }
  58     }
  59
  60     return true;
  61 }
  62
  63 template <class T>
  64 inline T
  65 leastSigBit(T n)
  66 {
  67     return n & ~(n - 1);
  68 }
  69
  70 template <class T>
  71 inline bool
  72 isPowerOf2(T n)
  73 {
  74     return n != 0 && leastSigBit(n) == n;
  75 }
  76
  77 inline int
  78 floorLog2(unsigned x)
  79 {
  80     assert(x > 0);
  81
  82     int y = 0;
  83
  84     if (x & 0xffff0000) { y += 16; x >>= 16; }
  85     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
  86     if (x & 0x000000f0) { y +=  4; x >>=  4; }
  87     if (x & 0x0000000c) { y +=  2; x >>=  2; }
  88     if (x & 0x00000002) { y +=  1; }
  89
  90     return y;
  91 }
  92
  93 inline int
  94 floorLog2(unsigned long x)
  95 {
  96     assert(x > 0);
  97
  98     int y = 0;
  99
 100 #if defined(__LP64__)
 101     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
 102 #endif
 103     if (x & 0xffff0000) { y += 16; x >>= 16; }
 104     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
 105     if (x & 0x000000f0) { y +=  4; x >>=  4; }
 106     if (x & 0x0000000c) { y +=  2; x >>=  2; }
 107     if (x & 0x00000002) { y +=  1; }
 108
 109     return y;
 110 }
 111
 112 inline int
 113 floorLog2(unsigned long long x)
 114 {
 115     assert(x > 0);
 116
 117     int y = 0;
 118
 119     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
 120     if (x & ULL(0x00000000ffff0000)) { y += 16; x >>= 16; }
 121     if (x & ULL(0x000000000000ff00)) { y +=  8; x >>=  8; }
 122     if (x & ULL(0x00000000000000f0)) { y +=  4; x >>=  4; }
 123     if (x & ULL(0x000000000000000c)) { y +=  2; x >>=  2; }
 124     if (x & ULL(0x0000000000000002)) { y +=  1; }
 125
 126     return y;
 127 }
 128
 129 inline int
 130 floorLog2(int x)
 131 {
 132     assert(x > 0);
 133     return floorLog2((unsigned)x);
 134 }
 135
 136 inline int
 137 floorLog2(long x)
 138 {
 139     assert(x > 0);
 140     return floorLog2((unsigned long)x);
 141 }
 142
 143 inline int
 144 floorLog2(long long x)
 145 {
 146     assert(x > 0);
 147     return floorLog2((unsigned long long)x);
 148 }
 149
 150 template <class T>
 151 inline int
 152 ceilLog2(T n)
 153 {
 154     if (n == 1)
 155         return 0;
 156
 157     return floorLog2(n - (T)1) + 1;
 158 }
 159
 160 template <class T>
 161 inline T
 162 floorPow2(T n)
 163 {
 164     return (T)1 << floorLog2(n);
 165 }
 166
 167 template <class T>
 168 inline T
 169 ceilPow2(T n)
 170 {
 171     return (T)1 << ceilLog2(n);
 172 }
 173
 174 template <class T>
 175 inline T
 176 divCeil(T a, T b)
 177 {
 178     return (a + b - 1) / b;
 179 }
 180
 181 template <class T>
 182 inline T
 183 roundUp(T val, int align)
 184 {
 185     T mask = (T)align - 1;
 186     return (val + mask) & ~mask;
 187 }
 188
 189 template <class T>
 190 inline T
 191 roundDown(T val, int align)
 192 {
 193     T mask = (T)align - 1;
 194     return val & ~mask;
 195 }
 196
 197 inline bool
 198 isHex(char c)
 199 {
 200     return (c >= '0' && c <= '9') ||
 201         (c >= 'A' && c <= 'F') ||
 202         (c >= 'a' && c <= 'f');
 203 }
 204
 205 inline bool
 206 isOct(char c)
 207 {
 208     return c >= '0' && c <= '7';
 209 }
 210
 211 inline bool
 212 isDec(char c)
 213 {
 214     return c >= '0' && c <= '9';
 215 }
 216
 217 inline int
 218 hex2Int(char c)
 219 {
 220   if (c >= '0' && c <= '9')
 221     return (c - '0');
 222
 223   if (c >= 'A' && c <= 'F')
 224     return (c - 'A') + 10;
 225
 226   if (c >= 'a' && c <= 'f')
 227     return (c - 'a') + 10;
 228
 229   return 0;
 230 }
 231
 232 #endif // __BASE_INTMATH_HH__