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1da177e4 LT |
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 | */ | |
49 | int | |
50 | dbl_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 | } |