base/intmath.hh

   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.
  37 int PrevPrime(int n);
  38
  39 // Determine if a number is prime
  40 template <class T>
  41 inline bool
  42 IsPrime(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
  61 template <class T>
  62 inline T
  63 LeastSigBit(T n)
  64 {
  65     return n & ~(n - 1);
  66 }
  67
  68 template <class T>
  69 inline bool
  70 IsPowerOf2(T n)
  71 {
  72     return n != 0 && LeastSigBit(n) == n;
  73 }
  74
  75 inline int
  76 FloorLog2(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
  91 inline int
  92 FloorLog2(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
 108 inline int
 109 FloorLog2(int32_t x)
 110 {
 111     assert(x > 0);
 112     return FloorLog2((uint32_t)x);
 113 }
 114
 115 inline int
 116 FloorLog2(int64_t x)
 117 {
 118     assert(x > 0);
 119     return FloorLog2((uint64_t)x);
 120 }
 121
 122 #if defined(__APPLE__)
 123 inline int
 124 FloorLog2(size_t x)
 125 {
 126     assert(x > 0);
 127     assert(sizeof(size_t) == 4 || sizeof(size_t) == 8);
 128
 129     // It's my hope that this is optimized away?
 130     if (sizeof(size_t) == 4)
 131         return FloorLog2((uint32_t)x);
 132      else if (sizeof(size_t) == 8)
 133         return FloorLog2((uint64_t)x);
 134
 135 }
 136 #endif
 137
 138 template <class T>
 139 inline int
 140 CeilLog2(T n)
 141 {
 142     if (n == 1)
 143         return 0;
 144
 145     return FloorLog2(n - (T)1) + 1;
 146 }
 147
 148 template <class T>
 149 inline T
 150 FloorPow2(T n)
 151 {
 152     return (T)1 << FloorLog2(n);
 153 }
 154
 155 template <class T>
 156 inline T
 157 CeilPow2(T n)
 158 {
 159     return (T)1 << CeilLog2(n);
 160 }
 161
 162 template <class T>
 163 inline T
 164 DivCeil(T a, T b)
 165 {
 166     return (a + b - 1) / b;
 167 }
 168
 169 template <class T>
 170 inline T
 171 RoundUp(T val, T align)
 172 {
 173     T mask = align - 1;
 174     return (val + mask) & ~mask;
 175 }
 176
 177 template <class T>
 178 inline T
 179 RoundDown(T val, T align)
 180 {
 181     T mask = align - 1;
 182     return val & ~mask;
 183 }
 184
 185 inline bool
 186 IsHex(char c)
 187 {
 188     return c >= '0' && c <= '9' ||
 189         c >= 'A' && c <= 'F' ||
 190         c >= 'a' && c <= 'f';
 191 }
 192
 193 inline bool
 194 IsOct(char c)
 195 {
 196     return c >= '0' && c <= '7';
 197 }
 198
 199 inline bool
 200 IsDec(char c)
 201 {
 202     return c >= '0' && c <= '9';
 203 }
 204
 205 inline int
 206 Hex2Int(char c)
 207 {
 208   if (c >= '0' && c <= '9')
 209     return (c - '0');
 210
 211   if (c >= 'A' && c <= 'F')
 212     return (c - 'A') + 10;
 213
 214   if (c >= 'a' && c <= 'f')
 215     return (c - 'a') + 10;
 216
 217   return 0;
 218 }
 219
 220 #endif // __INTMATH_HH__