base/intmath.hh

   1 /*
   2  * Copyright (c) 2001, 2003 The Regents of The University of Michigan
   3  * All rights reserved.
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   5  * Redistribution and use in source and binary forms, with or without
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   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
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  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  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 inline int
 123 FloorLog2(size_t x)
 124 {
 125     assert(x > 0);
 126     assert(sizeof(size_t) == 4 || sizeof(size_t) == 8);
 127
 128     // It's my hope that this is optimized away?
 129     if (sizeof(size_t) == 4)
 130         return FloorLog2((uint32_t)x);
 131      else if (sizeof(size_t) == 8)
 132         return FloorLog2((uint64_t)x);
 133
 134 }
 135
 136 template <class T>
 137 inline int
 138 CeilLog2(T n)
 139 {
 140     if (n == 1)
 141         return 0;
 142
 143     return FloorLog2(n - (T)1) + 1;
 144 }
 145
 146 template <class T>
 147 inline T
 148 FloorPow2(T n)
 149 {
 150     return (T)1 << FloorLog2(n);
 151 }
 152
 153 template <class T>
 154 inline T
 155 CeilPow2(T n)
 156 {
 157     return (T)1 << CeilLog2(n);
 158 }
 159
 160 template <class T>
 161 inline T
 162 DivCeil(T a, T b)
 163 {
 164     return (a + b - 1) / b;
 165 }
 166
 167 template <class T>
 168 inline T
 169 RoundUp(T val, T align)
 170 {
 171     T mask = align - 1;
 172     return (val + mask) & ~mask;
 173 }
 174
 175 template <class T>
 176 inline T
 177 RoundDown(T val, T align)
 178 {
 179     T mask = align - 1;
 180     return val & ~mask;
 181 }
 182
 183 inline bool
 184 IsHex(char c)
 185 {
 186     return c >= '0' && c <= '9' ||
 187         c >= 'A' && c <= 'F' ||
 188         c >= 'a' && c <= 'f';
 189 }
 190
 191 inline bool
 192 IsOct(char c)
 193 {
 194     return c >= '0' && c <= '7';
 195 }
 196
 197 inline bool
 198 IsDec(char c)
 199 {
 200     return c >= '0' && c <= '9';
 201 }
 202
 203 inline int
 204 Hex2Int(char c)
 205 {
 206   if (c >= '0' && c <= '9')
 207     return (c - '0');
 208
 209   if (c >= 'A' && c <= 'F')
 210     return (c - 'A') + 10;
 211
 212   if (c >= 'a' && c <= 'f')
 213     return (c - 'a') + 10;
 214
 215   return 0;
 216 }
 217
 218 #endif // __INTMATH_HH__