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50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
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/* s_logbl.c -- long double version of s_logb.c.
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* Conversion to long double by Ulrich Drepper,
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* Cygnus Support, drepper@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* long double logbl(x)
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* IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
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* Use ilogb instead.
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*/
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#include <math.h>
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#include <math_private.h>
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long double
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__logbl (long double x)
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{
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int32_t es, lx, ix;
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GET_LDOUBLE_WORDS (es, ix, lx, x);
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es &= 0x7fff; /* exponent */
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if ((es | ix | lx) == 0)
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return -1.0 / fabsl (x);
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if (es == 0x7fff)
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return x * x;
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if (es == 0) /* IEEE 754 logb */
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{
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/* POSIX specifies that denormal number is treated as
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though it were normalized. */
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if (ix == 0)
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es = -(__builtin_clz (lx) + 32);
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else
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es = -__builtin_clz (ix);
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}
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return (long double) (es - 16383);
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}
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weak_alias (__logbl, logbl)
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