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dfcmp.c
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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) <[email protected]>
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
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() ) {
81  return(INVALIDEXCEPTION);
82  }
83  else Set_invalidflag();
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. */
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  {
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  {
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  {
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  {
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  {
177  }
178  }
179  }
180  return(NOEXCEPTION);
181  }