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sfcmp.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/sfcmp.c $Revision: 1.1 $
26  *
27  * Purpose:
28  * sgl_cmp: compare two values
29  *
30  * External Interfaces:
31  * sgl_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 #include "float.h"
43 #include "sgl_float.h"
44 
45 /*
46  * sgl_cmp: compare two values
47  */
48 int
50  unsigned int cond, unsigned int *status)
51 
52  /* The predicate to be tested */
53 
54  {
55  register unsigned int left, right;
56  register int xorresult;
57 
58  /* Create local copies of the numbers */
59  left = *leftptr;
60  right = *rightptr;
61 
62  /*
63  * Test for NaN
64  */
65  if( (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
66  || (Sgl_exponent(right) == SGL_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( ( (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
72  && Sgl_isnotzero_mantissa(left)
73  && (Exception(cond) || Sgl_isone_signaling(left)))
74  ||
76  && Sgl_isnotzero_mantissa(right)
77  && (Exception(cond) || Sgl_isone_signaling(right)) ) )
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( ((Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
90  && Sgl_isnotzero_mantissa(left))
91  ||
93  && Sgl_isnotzero_mantissa(right)) )
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  Sgl_xortointp1(left,right,xorresult);
104  if( xorresult < 0 )
105  {
106  /* left negative => less, left positive => greater.
107  * equal is possible if both operands are zeros. */
108  if( Sgl_iszero_exponentmantissa(left)
109  && Sgl_iszero_exponentmantissa(right) )
110  {
111  Set_status_cbit(Equal(cond));
112  }
113  else if( Sgl_isone_sign(left) )
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( Sgl_all(left) == Sgl_all(right) )
125  {
126  Set_status_cbit(Equal(cond));
127  }
128  else if( Sgl_iszero_sign(left) )
129  {
130  /* Positive compare */
131  if( Sgl_all(left) < Sgl_all(right) )
132  {
133  Set_status_cbit(Lessthan(cond));
134  }
135  else
136  {
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( Sgl_all(left) > Sgl_all(right) )
146  {
147  Set_status_cbit(Lessthan(cond));
148  }
149  else
150  {
152  }
153  }
154  return(NOEXCEPTION);
155  }