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sfcmp.c revision 1.1 
      1 /*	$NetBSD: sfcmp.c,v 1.1 2002/06/05 01:04:26 fredette Exp $	*/
      2 
      3 /*	$OpenBSD: sfcmp.c,v 1.4 2001/03/29 03:58:19 mickey Exp $	*/
      4 
      5 /*
      6  * Copyright 1996 1995 by Open Software Foundation, Inc.
      7  *              All Rights Reserved
      8  *
      9  * Permission to use, copy, modify, and distribute this software and
     10  * its documentation for any purpose and without fee is hereby granted,
     11  * provided that the above copyright notice appears in all copies and
     12  * that both the copyright notice and this permission notice appear in
     13  * supporting documentation.
     14  *
     15  * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
     16  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     17  * FOR A PARTICULAR PURPOSE.
     18  *
     19  * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
     20  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
     21  * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
     22  * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     23  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     24  *
     25  */
     26 /*
     27  * pmk1.1
     28  */
     29 /*
     30  * (c) Copyright 1986 HEWLETT-PACKARD COMPANY
     31  *
     32  * To anyone who acknowledges that this file is provided "AS IS"
     33  * without any express or implied warranty:
     34  *     permission to use, copy, modify, and distribute this file
     35  * for any purpose is hereby granted without fee, provided that
     36  * the above copyright notice and this notice appears in all
     37  * copies, and that the name of Hewlett-Packard Company not be
     38  * used in advertising or publicity pertaining to distribution
     39  * of the software without specific, written prior permission.
     40  * Hewlett-Packard Company makes no representations about the
     41  * suitability of this software for any purpose.
     42  */
     43 
     44 #include "../spmath/float.h"
     45 #include "../spmath/sgl_float.h"
     46 
     47 /*
     48  * sgl_cmp: compare two values
     49  */
     50 int
     51 sgl_fcmp(leftptr, rightptr, cond, status)
     52     sgl_floating_point *leftptr, *rightptr;
     53     unsigned int cond; /* The predicate to be tested */
     54     unsigned int *status;
     55     {
     56     register unsigned int left, right;
     57     register int xorresult;
     58 
     59     /* Create local copies of the numbers */
     60     left = *leftptr;
     61     right = *rightptr;
     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