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      1 /*	$NetBSD: sfcmp.c,v 1.4 2012/02/04 17:03:10 skrll 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 1.4 2012/02/04 17:03:10 skrll 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(sgl_floating_point *leftptr, sgl_floating_point *rightptr,
     55     unsigned int cond, unsigned int *status)
     56 {
     57     register unsigned int left, right;
     58     register int xorresult;
     59 
     60     /* Create local copies of the numbers */
     61     left = *leftptr;
     62     right = *rightptr;
     63     /*
     64      * Test for NaN
     65      */
     66     if(    (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     67 	|| (Sgl_exponent(right) == SGL_INFINITY_EXPONENT) )
     68 	{
     69 	/* Check if a NaN is involved.  Signal an invalid exception when
     70 	 * comparing a signaling NaN or when comparing quiet NaNs and the
     71 	 * low bit of the condition is set */
     72 	if( (  (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     73 	    && Sgl_isnotzero_mantissa(left)
     74 	    && (Exception(cond) || Sgl_isone_signaling(left)))
     75 	   ||
     76 	    (  (Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
     77 	    && Sgl_isnotzero_mantissa(right)
     78 	    && (Exception(cond) || Sgl_isone_signaling(right)) ) )
     79 	    {
     80 	    if( Is_invalidtrap_enabled() ) {
     81 		Set_status_cbit(Unordered(cond));
     82 		return(INVALIDEXCEPTION);
     83 	    }
     84 	    else Set_invalidflag();
     85 	    Set_status_cbit(Unordered(cond));
     86 	    return(NOEXCEPTION);
     87 	    }
     88 	/* All the exceptional conditions are handled, now special case
     89 	   NaN compares */
     90 	else if( ((Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
     91 	    && Sgl_isnotzero_mantissa(left))
     92 	   ||
     93 	    ((Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
     94 	    && Sgl_isnotzero_mantissa(right)) )
     95 	    {
     96 	    /* NaNs always compare unordered. */
     97 	    Set_status_cbit(Unordered(cond));
     98 	    return(NOEXCEPTION);
     99 	    }
    100 	/* infinities will drop down to the normal compare mechanisms */
    101 	}
    102     /* First compare for unequal signs => less or greater or
    103      * special equal case */
    104     Sgl_xortointp1(left,right,xorresult);
    105     if( xorresult < 0 )
    106 	{
    107 	/* left negative => less, left positive => greater.
    108 	 * equal is possible if both operands are zeros. */
    109 	if( Sgl_iszero_exponentmantissa(left)
    110 	  && Sgl_iszero_exponentmantissa(right) )
    111 	    {
    112 	    Set_status_cbit(Equal(cond));
    113 	    }
    114 	else if( Sgl_isone_sign(left) )
    115 	    {
    116 	    Set_status_cbit(Lessthan(cond));
    117 	    }
    118 	else
    119 	    {
    120 	    Set_status_cbit(Greaterthan(cond));
    121 	    }
    122 	}
    123     /* Signs are the same.  Treat negative numbers separately
    124      * from the positives because of the reversed sense.  */
    125     else if( Sgl_all(left) == Sgl_all(right) )
    126 	{
    127 	Set_status_cbit(Equal(cond));
    128 	}
    129     else if( Sgl_iszero_sign(left) )
    130 	{
    131 	/* Positive compare */
    132 	if( Sgl_all(left) < Sgl_all(right) )
    133 	    {
    134 	    Set_status_cbit(Lessthan(cond));
    135 	    }
    136 	else
    137 	    {
    138 	    Set_status_cbit(Greaterthan(cond));
    139 	    }
    140 	}
    141     else
    142 	{
    143 	/* Negative compare.  Signed or unsigned compares
    144 	 * both work the same.  That distinction is only
    145 	 * important when the sign bits differ. */
    146 	if( Sgl_all(left) > Sgl_all(right) )
    147 	    {
    148 	    Set_status_cbit(Lessthan(cond));
    149 	    }
    150 	else
    151 	    {
    152 	    Set_status_cbit(Greaterthan(cond));
    153 	    }
    154 	}
    155 	return(NOEXCEPTION);
    156     }
    157