arch/parisc/math-emu/sfcmp.c

   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) <bame@debian.org>
   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
  49 sgl_fcmp (sgl_floating_point * leftptr, sgl_floating_point * rightptr,
  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            ||
  75             (  (Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
  76             && Sgl_isnotzero_mantissa(right)
  77             && (Exception(cond) || Sgl_isone_signaling(right)) ) )
  78             {
  79             if( Is_invalidtrap_enabled() ) {
  80                 Set_status_cbit(Unordered(cond));
  81                 return(INVALIDEXCEPTION);
  82             }
  83             else Set_invalidflag();
  84             Set_status_cbit(Unordered(cond));
  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            ||
  92             ((Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
  93             && Sgl_isnotzero_mantissa(right)) )
  94             {
  95             /* NaNs always compare unordered. */
  96             Set_status_cbit(Unordered(cond));
  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             {
 119             Set_status_cbit(Greaterthan(cond));
 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             {
 137             Set_status_cbit(Greaterthan(cond));
 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             {
 151             Set_status_cbit(Greaterthan(cond));
 152             }
 153         }
 154         return(NOEXCEPTION);
 155     }