1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
/* $OpenBSD: fpu_compare.c,v 1.2 2012/12/05 23:19:59 deraadt Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)fpu_compare.c 8.1 (Berkeley) 6/11/93
* $NetBSD: fpu_compare.c,v 1.3 2001/08/26 05:46:31 eeh Exp $
*/
#if 0
__FBSDID("$FreeBSD: src/lib/libc/sparc64/fpu/fpu_compare.c,v 1.4 2002/03/22 21:52:58 obrien Exp $");
#endif
/*
* CMP and CMPE instructions.
*
* These rely on the fact that our internal wide format is achieved by
* adding zero bits to the end of narrower mantissas.
*/
#include <sys/types.h>
#include <machine/frame.h>
#include <machine/fsr.h>
#include "fpu_arith.h"
#include "fpu_emu.h"
#include "fpu_extern.h"
static u_long fcc_nmask[] = {
~FSR_FCC,
~FSR_FCC1,
~FSR_FCC2,
~FSR_FCC3
};
/* XXX: we don't use the FSR_FCCx macros here; it's much easier this way. */
static int fcc_shift[] = {
FSR_FCC_SHIFT,
FSR_FCC1_SHIFT,
FSR_FCC2_SHIFT,
FSR_FCC3_SHIFT
};
/*
* Perform a compare instruction (with or without unordered exception).
* This updates the fcc field in the fsr.
*
* If either operand is NaN, the result is unordered. For cmpe, this
* causes an NV exception. Everything else is ordered:
* |Inf| > |numbers| > |0|.
* We already arranged for fp_class(Inf) > fp_class(numbers) > fp_class(0),
* so we get this directly. Note, however, that two zeros compare equal
* regardless of sign, while everything else depends on sign.
*
* Incidentally, two Infs of the same sign compare equal (per the 80387
* manual---it would be nice if the SPARC documentation were more
* complete).
*/
void
__fpu_compare(struct fpemu *fe, int cmpe, int fcc)
{
struct fpn *a, *b;
int cc;
FPU_DECL_CARRY
a = &fe->fe_f1;
b = &fe->fe_f2;
if (ISNAN(a) || ISNAN(b)) {
/*
* In any case, we already got an exception for signalling
* NaNs; here we may replace that one with an identical
* exception, but so what?.
*/
if (cmpe)
fe->fe_cx = FSR_NV;
cc = FSR_CC_UO;
goto done;
}
/*
* Must handle both-zero early to avoid sign goofs. Otherwise,
* at most one is 0, and if the signs differ we are done.
*/
if (ISZERO(a) && ISZERO(b)) {
cc = FSR_CC_EQ;
goto done;
}
if (a->fp_sign) { /* a < 0 (or -0) */
if (!b->fp_sign) { /* b >= 0 (or if a = -0, b > 0) */
cc = FSR_CC_LT;
goto done;
}
} else { /* a > 0 (or +0) */
if (b->fp_sign) { /* b <= -0 (or if a = +0, b < 0) */
cc = FSR_CC_GT;
goto done;
}
}
/*
* Now the signs are the same (but may both be negative). All
* we have left are these cases:
*
* |a| < |b| [classes or values differ]
* |a| > |b| [classes or values differ]
* |a| == |b| [classes and values identical]
*
* We define `diff' here to expand these as:
*
* |a| < |b|, a,b >= 0: a < b => FSR_CC_LT
* |a| < |b|, a,b < 0: a > b => FSR_CC_GT
* |a| > |b|, a,b >= 0: a > b => FSR_CC_GT
* |a| > |b|, a,b < 0: a < b => FSR_CC_LT
*/
#define opposite_cc(cc) ((cc) == FSR_CC_LT ? FSR_CC_GT : FSR_CC_LT)
#define diff(magnitude) (a->fp_sign ? opposite_cc(magnitude) : (magnitude))
if (a->fp_class < b->fp_class) { /* |a| < |b| */
cc = diff(FSR_CC_LT);
goto done;
}
if (a->fp_class > b->fp_class) { /* |a| > |b| */
cc = diff(FSR_CC_GT);
goto done;
}
/* now none can be 0: only Inf and numbers remain */
if (ISINF(a)) { /* |Inf| = |Inf| */
cc = FSR_CC_EQ;
goto done;
}
/*
* Only numbers remain. To compare two numbers in magnitude, we
* simply subtract them.
*/
a = __fpu_sub(fe);
if (a->fp_class == FPC_ZERO)
cc = FSR_CC_EQ;
else
cc = diff(FSR_CC_GT);
done:
fe->fe_fsr = (fe->fe_fsr & fcc_nmask[fcc]) |
((u_long)cc << fcc_shift[fcc]);
}
|
