1 /* $OpenBSD: dfcmp.c,v 1.6 2002/09/20 19:26:59 mickey Exp $ */
2 /*
3 (c) Copyright 1986 HEWLETT-PACKARD COMPANY
4 To anyone who acknowledges that this file is provided "AS IS"
5 without any express or implied warranty:
6 permission to use, copy, modify, and distribute this file
7 for any purpose is hereby granted without fee, provided that
8 the above copyright notice and this notice appears in all
9 copies, and that the name of Hewlett-Packard Company not be
10 used in advertising or publicity pertaining to distribution
11 of the software without specific, written prior permission.
12 Hewlett-Packard Company makes no representations about the
13 suitability of this software for any purpose.
14 */
15 /* @(#)dfcmp.c: Revision: 1.7.88.2 Date: 93/12/08 13:26:38 */
16
17 #include "float.h"
18 #include "dbl_float.h"
19
20 /*
21 * dbl_cmp: compare two values
22 */
23 int
dbl_fcmp(leftptr,rightptr,cond,status)24 dbl_fcmp(leftptr, rightptr, cond, status)
25 dbl_floating_point *leftptr, *rightptr;
26 unsigned int cond; /* The predicate to be tested */
27 unsigned int *status;
28 {
29 register unsigned int leftp1, leftp2, rightp1, rightp2;
30 register int xorresult;
31
32 /* Create local copies of the numbers */
33 Dbl_copyfromptr(leftptr,leftp1,leftp2);
34 Dbl_copyfromptr(rightptr,rightp1,rightp2);
35 /*
36 * Test for NaN
37 */
38 if( (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
39 || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) )
40 {
41 /* Check if a NaN is involved. Signal an invalid exception when
42 * comparing a signaling NaN or when comparing quiet NaNs and the
43 * low bit of the condition is set */
44 if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
45 && Dbl_isnotzero_mantissa(leftp1,leftp2)
46 && (Exception(cond) || Dbl_isone_signaling(leftp1)))
47 ||
48 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
49 && Dbl_isnotzero_mantissa(rightp1,rightp2)
50 && (Exception(cond) || Dbl_isone_signaling(rightp1))) )
51 {
52 if( Is_invalidtrap_enabled() ) {
53 Set_status_cbit(Unordered(cond));
54 return(INVALIDEXCEPTION);
55 }
56 else Set_invalidflag();
57 Set_status_cbit(Unordered(cond));
58 return(NOEXCEPTION);
59 }
60 /* All the exceptional conditions are handled, now special case
61 NaN compares */
62 else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
63 && Dbl_isnotzero_mantissa(leftp1,leftp2))
64 ||
65 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
66 && Dbl_isnotzero_mantissa(rightp1,rightp2)) )
67 {
68 /* NaNs always compare unordered. */
69 Set_status_cbit(Unordered(cond));
70 return(NOEXCEPTION);
71 }
72 /* infinities will drop down to the normal compare mechanisms */
73 }
74 /* First compare for unequal signs => less or greater or
75 * special equal case */
76 Dbl_xortointp1(leftp1,rightp1,xorresult);
77 if( xorresult < 0 )
78 {
79 /* left negative => less, left positive => greater.
80 * equal is possible if both operands are zeros. */
81 if( Dbl_iszero_exponentmantissa(leftp1,leftp2)
82 && Dbl_iszero_exponentmantissa(rightp1,rightp2) )
83 {
84 Set_status_cbit(Equal(cond));
85 }
86 else if( Dbl_isone_sign(leftp1) )
87 {
88 Set_status_cbit(Lessthan(cond));
89 }
90 else
91 {
92 Set_status_cbit(Greaterthan(cond));
93 }
94 }
95 /* Signs are the same. Treat negative numbers separately
96 * from the positives because of the reversed sense. */
97 else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2))
98 {
99 Set_status_cbit(Equal(cond));
100 }
101 else if( Dbl_iszero_sign(leftp1) )
102 {
103 /* Positive compare */
104 if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
105 {
106 Set_status_cbit(Lessthan(cond));
107 }
108 else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
109 {
110 Set_status_cbit(Greaterthan(cond));
111 }
112 else
113 {
114 /* Equal first parts. Now we must use unsigned compares to
115 * resolve the two possibilities. */
116 if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) )
117 {
118 Set_status_cbit(Lessthan(cond));
119 }
120 else
121 {
122 Set_status_cbit(Greaterthan(cond));
123 }
124 }
125 }
126 else
127 {
128 /* Negative compare. Signed or unsigned compares
129 * both work the same. That distinction is only
130 * important when the sign bits differ. */
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 return(NOEXCEPTION);
154 }
155