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69 lines
1.6 KiB
C
69 lines
1.6 KiB
C
/* Floating-point exponent.
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Copyright (C) 2012-2026 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This file 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 Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#if ! (defined USE_LONG_DOUBLE || defined USE_FLOAT)
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# include <config.h>
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#endif
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/* Specification. */
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#include <math.h>
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#include <limits.h>
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#ifdef USE_LONG_DOUBLE
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# define ILOGB ilogbl
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# define DOUBLE long double
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# define L_(literal) literal##L
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# define FREXP frexpl
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# define ISNAN isnanl
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#elif ! defined USE_FLOAT
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# define ILOGB ilogb
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# define DOUBLE double
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# define L_(literal) literal
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# define FREXP frexp
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# define ISNAN isnand
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#else /* defined USE_FLOAT */
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# define ILOGB ilogbf
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# define DOUBLE float
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# define L_(literal) literal##f
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# define FREXP frexpf
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# define ISNAN isnanf
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#endif
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int
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ILOGB (DOUBLE x)
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{
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if (isfinite (x))
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{
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if (x == L_(0.0))
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return FP_ILOGB0;
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else
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{
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int e;
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(void) FREXP (x, &e);
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return e - 1;
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}
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}
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else
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{
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if (ISNAN (x))
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return FP_ILOGBNAN;
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else
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return INT_MAX;
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}
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}
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