arch/parisc/math-emu/dfcmp.c

   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     }