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/logging.hh"
  37 #include "base/types.hh"
  38
  39 inline uint64_t
  40 power(uint32_t n, uint32_t e)
  41 {
  42     if (e > 20)
  43         warn("Warning, power() function is quite slow for large exponents\n");
  44
  45     if (e == 0)
  46         return 1;
  47
  48     uint64_t result = n;
  49     uint64_t old_result = 0;
  50     for (int x = 1; x < e; x++) {
  51         old_result = result;
  52         result *= n;
  53         if (old_result > result)
  54             warn("power() overflowed!\n");
  55     }
  56     return result;
  57 }
  58
  59
  60 inline int
  61 floorLog2(unsigned x)
  62 {
  63     assert(x > 0);
  64
  65     int y = 0;
  66
  67     if (x & 0xffff0000) { y += 16; x >>= 16; }
  68     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
  69     if (x & 0x000000f0) { y +=  4; x >>=  4; }
  70     if (x & 0x0000000c) { y +=  2; x >>=  2; }
  71     if (x & 0x00000002) { y +=  1; }
  72
  73     return y;
  74 }
  75
  76 inline int
  77 floorLog2(unsigned long x)
  78 {
  79     assert(x > 0);
  80
  81     int y = 0;
  82
  83 #if defined(__LP64__)
  84     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
  85 #endif
  86     if (x & 0xffff0000) { y += 16; x >>= 16; }
  87     if (x & 0x0000ff00) { y +=  8; x >>=  8; }
  88     if (x & 0x000000f0) { y +=  4; x >>=  4; }
  89     if (x & 0x0000000c) { y +=  2; x >>=  2; }
  90     if (x & 0x00000002) { y +=  1; }
  91
  92     return y;
  93 }
  94
  95 inline int
  96 floorLog2(unsigned long long x)
  97 {
  98     assert(x > 0);
  99
 100     int y = 0;
 101
 102     if (x & ULL(0xffffffff00000000)) { y += 32; x >>= 32; }
 103     if (x & ULL(0x00000000ffff0000)) { y += 16; x >>= 16; }
 104     if (x & ULL(0x000000000000ff00)) { y +=  8; x >>=  8; }
 105     if (x & ULL(0x00000000000000f0)) { y +=  4; x >>=  4; }
 106     if (x & ULL(0x000000000000000c)) { y +=  2; x >>=  2; }
 107     if (x & ULL(0x0000000000000002)) { y +=  1; }
 108
 109     return y;
 110 }
 111
 112 inline int
 113 floorLog2(int x)
 114 {
 115     assert(x > 0);
 116     return floorLog2((unsigned)x);
 117 }
 118
 119 inline int
 120 floorLog2(long x)
 121 {
 122     assert(x > 0);
 123     return floorLog2((unsigned long)x);
 124 }
 125
 126 inline int
 127 floorLog2(long long x)
 128 {
 129     assert(x > 0);
 130     return floorLog2((unsigned long long)x);
 131 }
 132
 133 template <class T>
 134 inline int
 135 ceilLog2(const T& n)
 136 {
 137     if (n == 1)
 138         return 0;
 139
 140     return floorLog2(n - (T)1) + 1;
 141 }
 142
 143 template <class T>
 144 inline bool
 145 isPowerOf2(const T& n)
 146 {
 147     return n != 0 && floorLog2(n) == ceilLog2(n);
 148 }
 149
 150 template <class T, class U>
 151 inline T
 152 divCeil(const T& a, const U& b)
 153 {
 154     return (a + b - 1) / b;
 155 }
 156
 157 /**
 158  * This function is used to align addresses in memory.
 159  *
 160  * @param val is the address to be aligned.
 161  * @param align is the alignment. Can only be a power of 2.
 162  * @return The aligned address. The smallest number divisible
 163  * by @param align which is greater than or equal to @param val.
 164 */
 165 template <class T, class U>
 166 inline T
 167 roundUp(const T& val, const U& align)
 168 {
 169     assert(isPowerOf2(align));
 170     T mask = (T)align - 1;
 171     return (val + mask) & ~mask;
 172 }
 173
 174 /**
 175  * This function is used to align addresses in memory.
 176  *
 177  * @param val is the address to be aligned.
 178  * @param align is the alignment. Can only be a power of 2.
 179  * @return The aligned address. The biggest number divisible
 180  * by @param align which is less than or equal to @param val.
 181 */
 182 template <class T, class U>
 183 inline T
 184 roundDown(const T& val, const U& align)
 185 {
 186     assert(isPowerOf2(align));
 187     T mask = (T)align - 1;
 188     return val & ~mask;
 189 }
 190
 191 #endif // __BASE_INTMATH_HH__