dfcmp.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
  4 *
  5 * Floating-point emulation code
  6 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
  7 */
  8/*
  9 * BEGIN_DESC
 10 *
 11 *  File:
 12 *	@(#)	pa/spmath/dfcmp.c		$Revision: 1.1 $
 13 *
 14 *  Purpose:
 15 *	dbl_cmp: compare two values
 16 *
 17 *  External Interfaces:
 18 *	dbl_fcmp(leftptr, rightptr, cond, status)
 19 *
 20 *  Internal Interfaces:
 21 *
 22 *  Theory:
 23 *	<<please update with a overview of the operation of this file>>
 24 *
 25 * END_DESC
 26*/
 27
 28
 29
 30#include "float.h"
 31#include "dbl_float.h"
 32    
 33/*
 34 * dbl_cmp: compare two values
 35 */
 36int
 37dbl_fcmp (dbl_floating_point * leftptr, dbl_floating_point * rightptr,
 38	  unsigned int cond, unsigned int *status)
 39                                           
 40                       /* The predicate to be tested */
 41                         
 42    {
 43    register unsigned int leftp1, leftp2, rightp1, rightp2;
 44    register int xorresult;
 45        
 46    /* Create local copies of the numbers */
 47    Dbl_copyfromptr(leftptr,leftp1,leftp2);
 48    Dbl_copyfromptr(rightptr,rightp1,rightp2);
 49    /*
 50     * Test for NaN
 51     */
 52    if(    (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
 53        || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) )
 54	{
 55	/* Check if a NaN is involved.  Signal an invalid exception when 
 56	 * comparing a signaling NaN or when comparing quiet NaNs and the
 57	 * low bit of the condition is set */
 58        if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
 59	    && Dbl_isnotzero_mantissa(leftp1,leftp2) 
 60	    && (Exception(cond) || Dbl_isone_signaling(leftp1)))
 61	   ||
 62	    ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
 63	    && Dbl_isnotzero_mantissa(rightp1,rightp2) 
 64	    && (Exception(cond) || Dbl_isone_signaling(rightp1))) )
 65	    {
 66	    if( Is_invalidtrap_enabled() ) {
 67	    	Set_status_cbit(Unordered(cond));
 68		return(INVALIDEXCEPTION);
 69	    }
 70	    else Set_invalidflag();
 71	    Set_status_cbit(Unordered(cond));
 72	    return(NOEXCEPTION);
 73	    }
 74	/* All the exceptional conditions are handled, now special case
 75	   NaN compares */
 76        else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT)
 77	    && Dbl_isnotzero_mantissa(leftp1,leftp2))
 78	   ||
 79	    ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT)
 80	    && Dbl_isnotzero_mantissa(rightp1,rightp2)) )
 81	    {
 82	    /* NaNs always compare unordered. */
 83	    Set_status_cbit(Unordered(cond));
 84	    return(NOEXCEPTION);
 85	    }
 86	/* infinities will drop down to the normal compare mechanisms */
 87	}
 88    /* First compare for unequal signs => less or greater or
 89     * special equal case */
 90    Dbl_xortointp1(leftp1,rightp1,xorresult);
 91    if( xorresult < 0 )
 92        {
 93        /* left negative => less, left positive => greater.
 94         * equal is possible if both operands are zeros. */
 95        if( Dbl_iszero_exponentmantissa(leftp1,leftp2) 
 96	  && Dbl_iszero_exponentmantissa(rightp1,rightp2) )
 97            {
 98	    Set_status_cbit(Equal(cond));
 99	    }
100	else if( Dbl_isone_sign(leftp1) )
101	    {
102	    Set_status_cbit(Lessthan(cond));
103	    }
104	else
105	    {
106	    Set_status_cbit(Greaterthan(cond));
107	    }
108        }
109    /* Signs are the same.  Treat negative numbers separately
110     * from the positives because of the reversed sense.  */
111    else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2))
112        {
113        Set_status_cbit(Equal(cond));
114        }
115    else if( Dbl_iszero_sign(leftp1) )
116        {
117        /* Positive compare */
118	if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
119	    {
120	    Set_status_cbit(Lessthan(cond));
121	    }
122	else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
123	    {
124	    Set_status_cbit(Greaterthan(cond));
125	    }
126	else
127	    {
128	    /* Equal first parts.  Now we must use unsigned compares to
129	     * resolve the two possibilities. */
130	    if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) )
131		{
132		Set_status_cbit(Lessthan(cond));
133		}
134	    else 
135		{
136		Set_status_cbit(Greaterthan(cond));
137		}
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( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) )
146	    {
147	    Set_status_cbit(Lessthan(cond));
148	    }
149	else if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) )
150	    {
151	    Set_status_cbit(Greaterthan(cond));
152	    }
153	else
154	    {
155	    /* Equal first parts.  Now we must use unsigned compares to
156	     * resolve the two possibilities. */
157	    if( Dbl_allp2(leftp2) > Dbl_allp2(rightp2) )
158		{
159		Set_status_cbit(Lessthan(cond));
160		}
161	    else 
162		{
163		Set_status_cbit(Greaterthan(cond));
164		}
165	    }
166        }
167	return(NOEXCEPTION);
168    }