condcodes.hh revision 4683
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 */ 40inline 41bool 42findCarry(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 */ 50inline 51bool 52findOverflow(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 */ 60inline 61bool 62findParity(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 */ 76inline 77bool 78findNegative(int width, uint64_t dest) { 79 return bits(dest, width - 1, width - 1); 80} 81 82/** 83 * Calculate the zero flag. 84 */ 85inline 86bool 87findZero(int width, uint64_t dest) { 88 return !(dest & mask(width)); 89} 90 91#endif // __BASE_CONDCODE_HH__ 92