condcodes.hh revision 4683:3b49d35562ed 
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