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80 lines
1.9 KiB
C
80 lines
1.9 KiB
C
/* Software floating-point emulation.
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ilogbl(x, exp)
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Copyright (C) 1999-2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Jakub Jelinek (jj@ultra.linux.cz).
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* ilogbl(long double x)
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* return the binary exponent of non-zero x
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* ilogbl(0) = 0x80000001
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* ilogbl(inf/NaN) = 0x7fffffff (no signal is raised)
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*/
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#include "soft-fp.h"
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#include "quad.h"
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#include <math.h>
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int __ieee754_ilogbl (long double x)
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{
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FP_DECL_EX;
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FP_DECL_Q(X);
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/*
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FP_UNPACK_Q(X, x);
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switch (X_c)
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{
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case FP_CLS_ZERO:
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return FP_ILOGB0;
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case FP_CLS_NAN:
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case FP_CLS_INF:
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return FP_ILOGBNAN;
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default:
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return X_e;
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}
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*/
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FP_UNPACK_RAW_Q(X, x);
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switch (X_e)
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{
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default:
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return X_e - _FP_EXPBIAS_Q;
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case 0:
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#if (2 * _FP_W_TYPE_SIZE) < _FP_FRACBITS_Q
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if (_FP_FRAC_ZEROP_4(X))
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return FP_ILOGB0;
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else
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{
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_FP_I_TYPE shift;
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_FP_FRAC_CLZ_4(shift, X);
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shift -= _FP_FRACXBITS_Q;
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return X_e - _FP_EXPBIAS_Q - 1 + shift;
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}
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#else
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if (_FP_FRAC_ZEROP_2(X))
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return FP_ILOGB0;
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else
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{
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_FP_I_TYPE shift;
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_FP_FRAC_CLZ_2(shift, X);
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shift -= _FP_FRACXBITS_Q;
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return X_e - _FP_EXPBIAS_Q - 1 + shift;
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}
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#endif
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case _FP_EXPBIAS_Q:
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return FP_ILOGBNAN;
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}
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}
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