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/sfcmp.c		$Revision: 1.1 $
 13 *
 14 *  Purpose:
 15 *	sgl_cmp: compare two values
 16 *
 17 *  External Interfaces:
 18 *	sgl_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#include "float.h"
 30#include "sgl_float.h"
 31    
 32/*
 33 * sgl_cmp: compare two values
 34 */
 35int
 36sgl_fcmp (sgl_floating_point * leftptr, sgl_floating_point * rightptr,
 37	  unsigned int cond, unsigned int *status)
 38                                           
 39                       /* The predicate to be tested */
 40                         
 41    {
 42    register unsigned int left, right;
 43    register int xorresult;
 44        
 45    /* Create local copies of the numbers */
 46    left = *leftptr;
 47    right = *rightptr;
 48
 49    /*
 50     * Test for NaN
 51     */
 52    if(    (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
 53        || (Sgl_exponent(right) == SGL_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( (  (Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
 59	    && Sgl_isnotzero_mantissa(left) 
 60	    && (Exception(cond) || Sgl_isone_signaling(left)))
 61	   ||
 62	    (  (Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
 63	    && Sgl_isnotzero_mantissa(right) 
 64	    && (Exception(cond) || Sgl_isone_signaling(right)) ) )
 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( ((Sgl_exponent(left) == SGL_INFINITY_EXPONENT)
 77	    && Sgl_isnotzero_mantissa(left))
 78	   ||
 79	    ((Sgl_exponent(right) == SGL_INFINITY_EXPONENT)
 80	    && Sgl_isnotzero_mantissa(right)) )
 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    Sgl_xortointp1(left,right,xorresult);
 91    if( xorresult < 0 )
 92        {
 93        /* left negative => less, left positive => greater.
 94         * equal is possible if both operands are zeros. */
 95        if( Sgl_iszero_exponentmantissa(left) 
 96	  && Sgl_iszero_exponentmantissa(right) )
 97            {
 98	    Set_status_cbit(Equal(cond));
 99	    }
100	else if( Sgl_isone_sign(left) )
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( Sgl_all(left) == Sgl_all(right) )
112        {
113        Set_status_cbit(Equal(cond));
114        }
115    else if( Sgl_iszero_sign(left) )
116        {
117        /* Positive compare */
118        if( Sgl_all(left) < Sgl_all(right) )
119	    {
120	    Set_status_cbit(Lessthan(cond));
121	    }
122	else
123	    {
124	    Set_status_cbit(Greaterthan(cond));
125	    }
126	}
127    else
128        {
129        /* Negative compare.  Signed or unsigned compares
130         * both work the same.  That distinction is only
131         * important when the sign bits differ. */
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	return(NOEXCEPTION);
142    }