LXR linux/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 */
  48int
  49sgl_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    }
 156