src/base/condcodes.hh

   1 /*
   2  * Copyright (c) 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: Gabe Black
  29  */
  30
  31 #ifndef __BASE_CONDCODE_HH__
  32 #define __BASE_CONDCODE_HH__
  33
  34 #include "base/bitfield.hh"
  35
  36 /**
  37  * Calculate the carry flag from an addition. This should work even when
  38  * a carry value is also added in.
  39  */
  40 inline
  41 bool
  42 findCarry(int width, uint64_t dest, uint64_t src1, uint64_t src2) {
  43     int shift = width - 1;
  44     return (~(dest >> shift) + (src1 >> shift) + (src2 >> shift)) & 0x2;
  45 }
  46
  47 /**
  48  * Calculate the overflow flag from an addition.
  49  */
  50 inline
  51 bool
  52 findOverflow(int width, uint64_t dest, uint64_t src1, uint64_t src2) {
  53     int shift = width - 1;
  54     return ((src1 ^ ~src2) & (src1 ^ dest)) & (1 << shift);
  55 }
  56
  57 /**
  58  * Calculate the parity of a value. 1 is for odd parity and 0 is for even.
  59  */
  60 inline
  61 bool
  62 findParity(int width, uint64_t dest) {
  63     dest &= width;
  64     dest ^= (dest >> 32);
  65     dest ^= (dest >> 16);
  66     dest ^= (dest >> 8);
  67     dest ^= (dest >> 4);
  68     dest ^= (dest >> 2);
  69     dest ^= (dest >> 1);
  70     return dest & 1;
  71 }
  72
  73 /**
  74  * Calculate the negative flag.
  75  */
  76 inline
  77 bool
  78 findNegative(int width, uint64_t dest) {
  79     return bits(dest, width - 1, width - 1);
  80 }
  81
  82 /**
  83  * Calculate the zero flag.
  84  */
  85 inline
  86 bool
  87 findZero(int width, uint64_t dest) {
  88     return !(dest & mask(width));
  89 }
  90
  91 #endif // __BASE_CONDCODE_HH__