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/* $Id: $ */
/* Copyright (C) 1997 Sverre Hvammen Johansen,
* Department of Informatics, University of Oslo.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "epsilon.h"
/******************************************************************************
REAL PROCEDURE ADDEPSILON(r) */
/* Denne rutinen skal h}ndtere alle floating-point formater.
* F|rste rutine h}ndterer IEEE-, IBM- og VAX-format effektivt.
* For disse formatene anntar den 32/64-bits representasjon.
* IBM-formatet er ikke testet da vi mangler maskin } kj|re det p}
* Andre rutine er en treg men portabel variant. */
#if FLOAT_IEEE | FLOAT_VAX | FLOAT_IBM
double
__raddepsilon (r)
double r;
{
union
{
double d;
struct
{
#if WORDS_BIGENDIAN || FLOAT_VAX
TYPE_32_INT i2;
unsigned TYPE_32_INT i1;
#else
unsigned TYPE_32_INT i1;
TYPE_32_INT i2;
#endif
}
dasii;
#if FLOAT_VAX
struct
{
short s1;
short s2;
short s3;
short s4;
}
dasssss;
#endif
}
value;
#if FLOAT_VAX
short s;
#endif
if (r == MAX_DOUBLE)
return (r);
value.d = r;
#if FLOAT_VAX
s = value.dasssss.s1;
value.dasssss.s1 = value.dasssss.s2;
value.dasssss.s2 = s;
s = value.dasssss.s3;
value.dasssss.s3 = value.dasssss.s4;
value.dasssss.s4 = s;
#endif
#if FLOAT_VAX
if (value.dasii.i2 == reswd && value.dasii.i1 == 0)
return (r);
#else
#if FLOAT_IEEE
if ((value.dasii.i2 & emask) == emask)
return (r);
#endif
#endif
if (r == -MIN_DOUBLE)
return (0.0);
if (r == 0.0)
return (MIN_DOUBLE);
if (value.dasii.i2 & signbit)
{
if ((value.dasii.i1--) == 0)
value.dasii.i2--;
}
else if ((++value.dasii.i1) == 0)
value.dasii.i2++;
#if FLOAT_IBM
if (value.dasii.i2 & emask && value.dasii.i2 & tmask)
if (value.dasii.i2 & signbit)
value.dasii.i2 -= adexp;
else
value.dasii.i2 += adexp;
#endif
#if FLOAT_VAX
s = value.dasssss.s1;
value.dasssss.s1 = value.dasssss.s2;
value.dasssss.s2 = s;
s = value.dasssss.s3;
value.dasssss.s3 = value.dasssss.s4;
value.dasssss.s4 = s;
#endif
return (value.d);
}
#else
double
__raddepsilon (r)
double r;
{
double s = MIN_DOUBLE,
t,
u;
u = r;
if (u >= MAX_DOUBLE)
return (r);
t = u + s;
while (t == u)
{
s *= 2.0;
t = u + s;
}
return (r + (t - u));
}
#endif
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