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Linux/arch/parisc/math-emu/dfcmp.c

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  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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