1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
4 *
5 * Floating-point emulation code
6 * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
7 */
8 /*
9 * BEGIN_DESC
10 *
11 * File:
12 * @(#) pa/spmath/dfcmp.c $Revision: 1.1 $
13 *
14 * Purpose:
15 * dbl_cmp: compare two values
16 *
17 * External Interfaces:
18 * dbl_fcmp(leftptr, rightptr, cond, status)
19 *
20 * Internal Interfaces:
21 *
22 * Theory:
23 * <<please update with a overview of the operation of this file>>
24 *
25 * END_DESC
26 */
27
28
29
30 #include "float.h"
31 #include "dbl_float.h"
32
33 /*
34 * dbl_cmp: compare two values
35 */
36 int
37 dbl_fcmp (dbl_floating_point * leftptr, dbl_floating_point * rightptr,
38 unsigned int cond, unsigned int *status)
39
40 /* The predicate to be tested */
41
42 {
43 register unsigned int leftp1, leftp2, rightp1, rightp2;
44 register int xorresult;
45
46 /* Create local copies of the numbers */
47 Dbl_copyfromptr(leftptr,leftp1,leftp2);
48 Dbl_copyfromptr(rightptr,rightp1,rightp2);
49 /*
50 * Test for NaN
51 */
52 if( (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
53 || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) )
54 {
55 /* Check if a NaN is involved. Signal an invalid exception when
56 * comparing a signaling NaN or when comparing quiet NaNs and the
57 * low bit of the condition is set */
58 if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
59 && Dbl_isnotzero_mantissa(leftp1,leftp2)
60 && (Exception(cond) || Dbl_isone_signaling(leftp1)))
61 ||
62 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
63 && Dbl_isnotzero_mantissa(rightp1,rightp2)
64 && (Exception(cond) || Dbl_isone_signaling(rightp1))) )
65 {
66 if( Is_invalidtrap_enabled() ) {
67 Set_status_cbit(Unordered(cond));
68 return(INVALIDEXCEPTION);
69 }
70 else Set_invalidflag();
71 Set_status_cbit(Unordered(cond));
72 return(NOEXCEPTION);
73 }
74 /* All the exceptional conditions are handled, now special case
75 NaN compares */
76 else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
77 && Dbl_isnotzero_mantissa(leftp1,leftp2))
78 ||
79 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
80 && Dbl_isnotzero_mantissa(rightp1,rightp2)) )
81 {
82 /* NaNs always compare unordered. */
83 Set_status_cbit(Unordered(cond));
84 return(NOEXCEPTION);
85 }
86 /* infinities will drop down to the normal compare mechanisms */
87 }
88 /* First compare for unequal signs => less or greater or
89 * special equal case */
90 Dbl_xortointp1(leftp1,rightp1,xorresult);
91 if( xorresult < 0 )
92 {
93 /* left negative => less, left positive => greater.
94 * equal is possible if both operands are zeros. */
95 if( Dbl_iszero_exponentmantissa(leftp1,leftp2)
96 && Dbl_iszero_exponentmantissa(rightp1,rightp2) )
97 {
98 Set_status_cbit(Equal(cond));
99 }
100 else if( Dbl_isone_sign(leftp1) )
101 {
102 Set_status_cbit(Lessthan(cond));
103 }
104 else
105 {
106 Set_status_cbit(Greaterthan(cond));
107 }
108 }
109 /* Signs are the same. Treat negative numbers separately
110 * from the positives because of the reversed sense. */
111 else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2))
112 {
113 Set_status_cbit(Equal(cond));
114 }
115 else if( Dbl_iszero_sign(leftp1) )
116 {
117 /* Positive compare */
118 if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
119 {
120 Set_status_cbit(Lessthan(cond));
121 }
122 else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
123 {
124 Set_status_cbit(Greaterthan(cond));
125 }
126 else
127 {
128 /* Equal first parts. Now we must use unsigned compares to
129 * resolve the two possibilities. */
130 if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) )
131 {
132 Set_status_cbit(Lessthan(cond));
133 }
134 else
135 {
136 Set_status_cbit(Greaterthan(cond));
137 }
138 }
139 }
140 else
141 {
142 /* Negative compare. Signed or unsigned compares
143 * both work the same. That distinction is only
144 * important when the sign bits differ. */
145 if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
146 {
147 Set_status_cbit(Lessthan(cond));
148 }
149 else if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
150 {
151 Set_status_cbit(Greaterthan(cond));
152 }
153 else
154 {
155 /* Equal first parts. Now we must use unsigned compares to
156 * resolve the two possibilities. */
157 if( Dbl_allp2(leftp2) > Dbl_allp2(rightp2) )
158 {
159 Set_status_cbit(Lessthan(cond));
160 }
161 else
162 {
163 Set_status_cbit(Greaterthan(cond));
164 }
165 }
166 }
167 return(NOEXCEPTION);
168 }
169
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