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sfcmp.c revision 1.2 
      1 /*	$NetBSD: sfcmp.c,v 1.2 2003/07/15 02:29:42 lukem 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 <sys/cdefs.h>
     45 __KERNEL_RCSID(0, "$NetBSD: sfcmp.c,v 1.2 2003/07/15 02:29:42 lukem Exp $");
     46 
     47 #include "../spmath/float.h"
     48 #include "../spmath/sgl_float.h"
     49 
     50 /*
     51  * sgl_cmp: compare two values
     52  */
     53 int
     54 sgl_fcmp(leftptr, rightptr, cond, status)
     55     sgl_floating_point *leftptr, *rightptr;
     56     unsigned int cond; /* The predicate to be tested */
     57     unsigned int *status;
     58     {
     59     register unsigned int left, right;
     60     register int xorresult;
     61 
     62     /* Create local copies of the numbers */
     63     left = *leftptr;
     64     right = *rightptr;
     65     /*
     66      * Test for NaN
     67      */
     68     if(    (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     69 	|| (Sgl_exponent(right) == SGL_INFINITY_EXPONENT) )
     70 	{
     71 	/* Check if a NaN is involved.  Signal an invalid exception when
     72 	 * comparing a signaling NaN or when comparing quiet NaNs and the
     73 	 * low bit of the condition is set */
     74 	if( (  (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     75 	    && Sgl_isnotzero_mantissa(left)
     76 	    && (Exception(cond) || Sgl_isone_signaling(left)))
     77 	   ||
     78 	    (  (Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
     79 	    && Sgl_isnotzero_mantissa(right)
     80 	    && (Exception(cond) || Sgl_isone_signaling(right)) ) )
     81 	    {
     82 	    if( Is_invalidtrap_enabled() ) {
     83 		Set_status_cbit(Unordered(cond));
     84 		return(INVALIDEXCEPTION);
     85 	    }
     86 	    else Set_invalidflag();
     87 	    Set_status_cbit(Unordered(cond));
     88 	    return(NOEXCEPTION);
     89 	    }
     90 	/* All the exceptional conditions are handled, now special case
     91 	   NaN compares */
     92 	else if( ((Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     93 	    && Sgl_isnotzero_mantissa(left))
     94 	   ||
     95 	    ((Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
     96 	    && Sgl_isnotzero_mantissa(right)) )
     97 	    {
     98 	    /* NaNs always compare unordered. */
     99 	    Set_status_cbit(Unordered(cond));
    100 	    return(NOEXCEPTION);
    101 	    }
    102 	/* infinities will drop down to the normal compare mechanisms */
    103 	}
    104     /* First compare for unequal signs => less or greater or
    105      * special equal case */
    106     Sgl_xortointp1(left,right,xorresult);
    107     if( xorresult < 0 )
    108 	{
    109 	/* left negative => less, left positive => greater.
    110 	 * equal is possible if both operands are zeros. */
    111 	if( Sgl_iszero_exponentmantissa(left)
    112 	  && Sgl_iszero_exponentmantissa(right) )
    113 	    {
    114 	    Set_status_cbit(Equal(cond));
    115 	    }
    116 	else if( Sgl_isone_sign(left) )
    117 	    {
    118 	    Set_status_cbit(Lessthan(cond));
    119 	    }
    120 	else
    121 	    {
    122 	    Set_status_cbit(Greaterthan(cond));
    123 	    }
    124 	}
    125     /* Signs are the same.  Treat negative numbers separately
    126      * from the positives because of the reversed sense.  */
    127     else if( Sgl_all(left) == Sgl_all(right) )
    128 	{
    129 	Set_status_cbit(Equal(cond));
    130 	}
    131     else if( Sgl_iszero_sign(left) )
    132 	{
    133 	/* Positive compare */
    134 	if( Sgl_all(left) < Sgl_all(right) )
    135 	    {
    136 	    Set_status_cbit(Lessthan(cond));
    137 	    }
    138 	else
    139 	    {
    140 	    Set_status_cbit(Greaterthan(cond));
    141 	    }
    142 	}
    143     else
    144 	{
    145 	/* Negative compare.  Signed or unsigned compares
    146 	 * both work the same.  That distinction is only
    147 	 * important when the sign bits differ. */
    148 	if( Sgl_all(left) > Sgl_all(right) )
    149 	    {
    150 	    Set_status_cbit(Lessthan(cond));
    151 	    }
    152 	else
    153 	    {
    154 	    Set_status_cbit(Greaterthan(cond));
    155 	    }
    156 	}
    157 	return(NOEXCEPTION);
    158     }
    159