mirror of git://gcc.gnu.org/git/gcc.git
121 lines
3.0 KiB
C
121 lines
3.0 KiB
C
/* Nelper routines to convert from integer to real.
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Copyright 2004 Free Software Foundation, Inc.
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Contributed by Paul Brook.
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This file is part of the GNU Fortran 95 runtime library (libgfortran).
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Libgfortran is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combine
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executable.)
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Ligbfortran is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public
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License along with libgfortran; see the file COPYING. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <math.h>
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#include "libgfortran.h"
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/* These routines can be sensitive to excess precision, so should really be
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compiled with -ffloat-store. */
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/* Return the largest value less than one representable in a REAL*4. */
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static inline GFC_REAL_4
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almostone_r4 ()
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{
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#ifdef HAVE_NEXTAFTERF
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return nextafterf (1.0f, 0.0f);
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#else
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/* The volatile is a hack to prevent excess precision on x86. */
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static volatile GFC_REAL_4 val = 0.0f;
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GFC_REAL_4 x;
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if (val != 0.0f)
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return val;
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val = 0.9999f;
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do
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{
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x = val;
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val = (val + 1.0f) / 2.0f;
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}
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while (val > x && val < 1.0f);
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if (val == 1.0f)
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val = x;
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return val;
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#endif
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}
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/* Return the largest value less than one representable in a REAL*8. */
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static inline GFC_REAL_8
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almostone_r8 ()
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{
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#ifdef HAVE_NEXTAFTER
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return nextafter (1.0, 0.0);
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#else
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static volatile GFC_REAL_8 val = 0.0;
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GFC_REAL_8 x;
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if (val != 0.0)
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return val;
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val = 0.9999;
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do
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{
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x = val;
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val = (val + 1.0) / 2.0;
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}
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while (val > x && val < 1.0);
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if (val == 1.0)
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val = x;
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return val;
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#endif
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}
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/* Convert an unsigned integer in the range [0..x] into a
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real the range [0..1). */
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GFC_REAL_4
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normalize_r4_i4 (GFC_UINTEGER_4 i, GFC_UINTEGER_4 x)
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{
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GFC_REAL_4 r;
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r = (GFC_REAL_4) i / (GFC_REAL_4) x;
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if (r == 1.0f)
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r = almostone_r4 ();
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return r;
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}
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/* Convert an unsigned integer in the range [0..x] into a
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real the range [0..1). */
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GFC_REAL_8
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normalize_r8_i8 (GFC_UINTEGER_8 i, GFC_UINTEGER_8 x)
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{
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GFC_REAL_8 r;
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r = (GFC_REAL_8) i / (GFC_REAL_8) x;
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if (r == 1.0)
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r = almostone_r8 ();
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return r;
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}
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