summaryrefslogtreecommitdiffstats
path: root/arch/parisc/math-emu/dfcmp.c
blob: 59521267ffcc8003ea07df5a8120b75ce8c7a618 (plain)
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
/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * BEGIN_DESC
 *
 *  File:
 *	@(#)	pa/spmath/dfcmp.c		$Revision: 1.1 $
 *
 *  Purpose:
 *	dbl_cmp: compare two values
 *
 *  External Interfaces:
 *	dbl_fcmp(leftptr, rightptr, cond, status)
 *
 *  Internal Interfaces:
 *
 *  Theory:
 *	<<please update with a overview of the operation of this file>>
 *
 * END_DESC
*/



#include "float.h"
#include "dbl_float.h"
    
/*
 * dbl_cmp: compare two values
 */
int
dbl_fcmp (dbl_floating_point * leftptr, dbl_floating_point * rightptr,
	  unsigned int cond, unsigned int *status)
                                           
                       /* The predicate to be tested */
                         
    {
    register unsigned int leftp1, leftp2, rightp1, rightp2;
    register int xorresult;
        
    /* Create local copies of the numbers */
    Dbl_copyfromptr(leftptr,leftp1,leftp2);
    Dbl_copyfromptr(rightptr,rightp1,rightp2);
    /*
     * Test for NaN
     */
    if(    (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
        || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) )
	{
	/* Check if a NaN is involved.  Signal an invalid exception when 
	 * comparing a signaling NaN or when comparing quiet NaNs and the
	 * low bit of the condition is set */
        if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
	    && Dbl_isnotzero_mantissa(leftp1,leftp2) 
	    && (Exception(cond) || Dbl_isone_signaling(leftp1)))
	   ||
	    ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
	    && Dbl_isnotzero_mantissa(rightp1,rightp2) 
	    && (Exception(cond) || Dbl_isone_signaling(rightp1))) )
	    {
	    if( Is_invalidtrap_enabled() ) {
	    	Set_status_cbit(Unordered(cond));
		return(INVALIDEXCEPTION);
	    }
	    else Set_invalidflag();
	    Set_status_cbit(Unordered(cond));
	    return(NOEXCEPTION);
	    }
	/* All the exceptional conditions are handled, now special case
	   NaN compares */
        else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
	    && Dbl_isnotzero_mantissa(leftp1,leftp2))
	   ||
	    ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
	    && Dbl_isnotzero_mantissa(rightp1,rightp2)) )
	    {
	    /* NaNs always compare unordered. */
	    Set_status_cbit(Unordered(cond));
	    return(NOEXCEPTION);
	    }
	/* infinities will drop down to the normal compare mechanisms */
	}
    /* First compare for unequal signs => less or greater or
     * special equal case */
    Dbl_xortointp1(leftp1,rightp1,xorresult);
    if( xorresult < 0 )
        {
        /* left negative => less, left positive => greater.
         * equal is possible if both operands are zeros. */
        if( Dbl_iszero_exponentmantissa(leftp1,leftp2) 
	  && Dbl_iszero_exponentmantissa(rightp1,rightp2) )
            {
	    Set_status_cbit(Equal(cond));
	    }
	else if( Dbl_isone_sign(leftp1) )
	    {
	    Set_status_cbit(Lessthan(cond));
	    }
	else
	    {
	    Set_status_cbit(Greaterthan(cond));
	    }
        }
    /* Signs are the same.  Treat negative numbers separately
     * from the positives because of the reversed sense.  */
    else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2))
        {
        Set_status_cbit(Equal(cond));
        }
    else if( Dbl_iszero_sign(leftp1) )
        {
        /* Positive compare */
	if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
	    {
	    Set_status_cbit(Lessthan(cond));
	    }
	else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
	    {
	    Set_status_cbit(Greaterthan(cond));
	    }
	else
	    {
	    /* Equal first parts.  Now we must use unsigned compares to
	     * resolve the two possibilities. */
	    if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) )
		{
		Set_status_cbit(Lessthan(cond));
		}
	    else 
		{
		Set_status_cbit(Greaterthan(cond));
		}
	    }
	}
    else
        {
        /* Negative compare.  Signed or unsigned compares
         * both work the same.  That distinction is only
         * important when the sign bits differ. */
	if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
	    {
	    Set_status_cbit(Lessthan(cond));
	    }
	else if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
	    {
	    Set_status_cbit(Greaterthan(cond));
	    }
	else
	    {
	    /* Equal first parts.  Now we must use unsigned compares to
	     * resolve the two possibilities. */
	    if( Dbl_allp2(leftp2) > Dbl_allp2(rightp2) )
		{
		Set_status_cbit(Lessthan(cond));
		}
	    else 
		{
		Set_status_cbit(Greaterthan(cond));
		}
	    }
        }
	return(NOEXCEPTION);
    }