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50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
/* s_logbl.c -- long double version of s_logb.c.
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* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
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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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#include <math_ldbl_opt.h>
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long double
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__logbl (long double x)
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{
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int64_t hx, rhx;
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double xhi;
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xhi = ldbl_high (x);
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EXTRACT_WORDS64 (hx, xhi);
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hx &= 0x7fffffffffffffffLL; /* high |x| */
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if (hx == 0)
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return -1.0 / fabs (x);
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if (hx >= 0x7ff0000000000000LL)
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return x * x;
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if (__glibc_unlikely ((rhx = hx >> 52) == 0))
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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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rhx -= __builtin_clzll (hx) - 12;
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}
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return (long double) (rhx - 1023);
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}
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#ifndef __logbl
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long_double_symbol (libm, __logbl, logbl);
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#endif
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