LXR linux/arch/parisc/math-emu/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    }
 169