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1/*
2 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
3 *
4 * Floating-point emulation code
5 * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
10 * any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21/*
22 * BEGIN_DESC
23 *
24 * File:
25 * @(#) pa/spmath/dfcmp.c $Revision: 1.1 $
26 *
27 * Purpose:
28 * dbl_cmp: compare two values
29 *
30 * External Interfaces:
31 * dbl_fcmp(leftptr, rightptr, cond, status)
32 *
33 * Internal Interfaces:
34 *
35 * Theory:
36 * <<please update with a overview of the operation of this file>>
37 *
38 * END_DESC
39*/
40
41
42
43#include "float.h"
44#include "dbl_float.h"
45
46/*
47 * dbl_cmp: compare two values
48 */
49int
50dbl_fcmp (dbl_floating_point * leftptr, dbl_floating_point * rightptr,
51 unsigned int cond, unsigned int *status)
52
53 /* The predicate to be tested */
54
55 {
56 register unsigned int leftp1, leftp2, rightp1, rightp2;
57 register int xorresult;
58
59 /* Create local copies of the numbers */
60 Dbl_copyfromptr(leftptr,leftp1,leftp2);
61 Dbl_copyfromptr(rightptr,rightp1,rightp2);
62 /*
63 * Test for NaN
64 */
65 if( (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
66 || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) )
67 {
68 /* Check if a NaN is involved. Signal an invalid exception when
69 * comparing a signaling NaN or when comparing quiet NaNs and the
70 * low bit of the condition is set */
71 if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
72 && Dbl_isnotzero_mantissa(leftp1,leftp2)
73 && (Exception(cond) || Dbl_isone_signaling(leftp1)))
74 ||
75 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
76 && Dbl_isnotzero_mantissa(rightp1,rightp2)
77 && (Exception(cond) || Dbl_isone_signaling(rightp1))) )
78 {
79 if( Is_invalidtrap_enabled() ) {
80 Set_status_cbit(Unordered(cond));
81 return(INVALIDEXCEPTION);
82 }
83 else Set_invalidflag();
84 Set_status_cbit(Unordered(cond));
85 return(NOEXCEPTION);
86 }
87 /* All the exceptional conditions are handled, now special case
88 NaN compares */
89 else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
90 && Dbl_isnotzero_mantissa(leftp1,leftp2))
91 ||
92 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
93 && Dbl_isnotzero_mantissa(rightp1,rightp2)) )
94 {
95 /* NaNs always compare unordered. */
96 Set_status_cbit(Unordered(cond));
97 return(NOEXCEPTION);
98 }
99 /* infinities will drop down to the normal compare mechanisms */
100 }
101 /* First compare for unequal signs => less or greater or
102 * special equal case */
103 Dbl_xortointp1(leftp1,rightp1,xorresult);
104 if( xorresult < 0 )
105 {
106 /* left negative => less, left positive => greater.
107 * equal is possible if both operands are zeros. */
108 if( Dbl_iszero_exponentmantissa(leftp1,leftp2)
109 && Dbl_iszero_exponentmantissa(rightp1,rightp2) )
110 {
111 Set_status_cbit(Equal(cond));
112 }
113 else if( Dbl_isone_sign(leftp1) )
114 {
115 Set_status_cbit(Lessthan(cond));
116 }
117 else
118 {
119 Set_status_cbit(Greaterthan(cond));
120 }
121 }
122 /* Signs are the same. Treat negative numbers separately
123 * from the positives because of the reversed sense. */
124 else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2))
125 {
126 Set_status_cbit(Equal(cond));
127 }
128 else if( Dbl_iszero_sign(leftp1) )
129 {
130 /* Positive compare */
131 if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
132 {
133 Set_status_cbit(Lessthan(cond));
134 }
135 else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
136 {
137 Set_status_cbit(Greaterthan(cond));
138 }
139 else
140 {
141 /* Equal first parts. Now we must use unsigned compares to
142 * resolve the two possibilities. */
143 if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) )
144 {
145 Set_status_cbit(Lessthan(cond));
146 }
147 else
148 {
149 Set_status_cbit(Greaterthan(cond));
150 }
151 }
152 }
153 else
154 {
155 /* Negative compare. Signed or unsigned compares
156 * both work the same. That distinction is only
157 * important when the sign bits differ. */
158 if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
159 {
160 Set_status_cbit(Lessthan(cond));
161 }
162 else if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
163 {
164 Set_status_cbit(Greaterthan(cond));
165 }
166 else
167 {
168 /* Equal first parts. Now we must use unsigned compares to
169 * resolve the two possibilities. */
170 if( Dbl_allp2(leftp2) > Dbl_allp2(rightp2) )
171 {
172 Set_status_cbit(Lessthan(cond));
173 }
174 else
175 {
176 Set_status_cbit(Greaterthan(cond));
177 }
178 }
179 }
180 return(NOEXCEPTION);
181 }