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/misc.hh"
  37 #include "base/types.hh"
  38
  39 // Returns the prime number one less than n.
  40 int prevPrime(int n);
  41
  42 // Determine if a number is prime
  43 template <class T>
  44 inline bool
  45 isPrime(const T& n)
  46 {
  47     T i;
  48
  49     if (n == 2 || n == 3)
  50         return true;
  51
  52     // Don't try every odd number to prove if it is a prime.
  53     // Toggle between every 2nd and 4th number.
  54     // (This is because every 6th odd number is divisible by 3.)
  55     for (i = 5; i*i <= n; i += 6) {
  56         if (((n % i) == 0 ) || ((n % (i + 2)) == 0) ) {
  57             return false;
  58         }
  59     }
  60
  61     return true;
  62 }
  63
  64 template <class T>
  65 inline T
  66 leastSigBit(const T& n)
  67 {
  68     return n & ~(n - 1);
  69 }
  70
  71 template <class T>
  72 inline bool
  73 isPowerOf2(const T& n)
  74 {
  75     return n != 0 && leastSigBit(n) == n;
  76 }
  77
  78 inline uint64_t
  79 power(uint32_t n, uint32_t e)
  80 {
  81     if (e > 20)
  82         warn("Warning, power() function is quite slow for large exponents\n");
  83
  84     if (e == 0)
  85         return 1;
  86
  87     uint64_t result = n;
  88     uint64_t old_result = 0;
  89     for (int x = 1; x < e; x++) {
  90         old_result = result;
  91         result *= n;
  92         if (old_result > result)
  93             warn("power() overflowed!\n");
  94     }
  95     return result;
  96 }
  97
  98
  99 inline int
 100 floorLog2(unsigned x)
 101 {
 102     assert(x > 0);
 103
 104     int y = 0;
 105
 106     if (x & 0xffff0000) { y += 16; x >>= 16; }
 107     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
 108     if (x & 0x000000f0) { y +=  4; x >>=  4; }
 109     if (x & 0x0000000c) { y +=  2; x >>=  2; }
 110     if (x & 0x00000002) { y +=  1; }
 111
 112     return y;
 113 }
 114
 115 inline int
 116 floorLog2(unsigned long x)
 117 {
 118     assert(x > 0);
 119
 120     int y = 0;
 121
 122 #if defined(__LP64__)
 123     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
 124 #endif
 125     if (x & 0xffff0000) { y += 16; x >>= 16; }
 126     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
 127     if (x & 0x000000f0) { y +=  4; x >>=  4; }
 128     if (x & 0x0000000c) { y +=  2; x >>=  2; }
 129     if (x & 0x00000002) { y +=  1; }
 130
 131     return y;
 132 }
 133
 134 inline int
 135 floorLog2(unsigned long long x)
 136 {
 137     assert(x > 0);
 138
 139     int y = 0;
 140
 141     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
 142     if (x & ULL(0x00000000ffff0000)) { y += 16; x >>= 16; }
 143     if (x & ULL(0x000000000000ff00)) { y +=  8; x >>=  8; }
 144     if (x & ULL(0x00000000000000f0)) { y +=  4; x >>=  4; }
 145     if (x & ULL(0x000000000000000c)) { y +=  2; x >>=  2; }
 146     if (x & ULL(0x0000000000000002)) { y +=  1; }
 147
 148     return y;
 149 }
 150
 151 inline int
 152 floorLog2(int x)
 153 {
 154     assert(x > 0);
 155     return floorLog2((unsigned)x);
 156 }
 157
 158 inline int
 159 floorLog2(long x)
 160 {
 161     assert(x > 0);
 162     return floorLog2((unsigned long)x);
 163 }
 164
 165 inline int
 166 floorLog2(long long x)
 167 {
 168     assert(x > 0);
 169     return floorLog2((unsigned long long)x);
 170 }
 171
 172 template <class T>
 173 inline int
 174 ceilLog2(const T& n)
 175 {
 176     if (n == 1)
 177         return 0;
 178
 179     return floorLog2(n - (T)1) + 1;
 180 }
 181
 182 template <class T>
 183 inline T
 184 floorPow2(const T& n)
 185 {
 186     return (T)1 << floorLog2(n);
 187 }
 188
 189 template <class T>
 190 inline T
 191 ceilPow2(const T& n)
 192 {
 193     return (T)1 << ceilLog2(n);
 194 }
 195
 196 template <class T, class U>
 197 inline T
 198 divCeil(const T& a, const U& b)
 199 {
 200     return (a + b - 1) / b;
 201 }
 202
 203 template <class T, class U>
 204 inline T
 205 roundUp(const T& val, const U& align)
 206 {
 207     T mask = (T)align - 1;
 208     return (val + mask) & ~mask;
 209 }
 210
 211 template <class T, class U>
 212 inline T
 213 roundDown(const T& val, const U& align)
 214 {
 215     T mask = (T)align - 1;
 216     return val & ~mask;
 217 }
 218
 219 inline bool
 220 isHex(char c)
 221 {
 222     return (c >= '0' && c <= '9') ||
 223         (c >= 'A' && c <= 'F') ||
 224         (c >= 'a' && c <= 'f');
 225 }
 226
 227 inline bool
 228 isOct(char c)
 229 {
 230     return c >= '0' && c <= '7';
 231 }
 232
 233 inline bool
 234 isDec(char c)
 235 {
 236     return c >= '0' && c <= '9';
 237 }
 238
 239 inline int
 240 hex2Int(char c)
 241 {
 242   if (c >= '0' && c <= '9')
 243     return (c - '0');
 244
 245   if (c >= 'A' && c <= 'F')
 246     return (c - 'A') + 10;
 247
 248   if (c >= 'a' && c <= 'f')
 249     return (c - 'a') + 10;
 250
 251   return 0;
 252 }
 253
 254 #endif // __BASE_INTMATH_HH__