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72 lines
1.9 KiB
C
72 lines
1.9 KiB
C
/* s_scalbnl.c -- long double version of s_scalbn.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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/*
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* scalbnl (long double x, int n)
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* scalbnl(x,n) returns x* 2**n computed by exponent
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* manipulation rather than by actually performing an
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* exponentiation or a multiplication.
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*/
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#include "math.h"
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#include "math_private.h"
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#ifdef __STDC__
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static const long double
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#else
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static long double
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#endif
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two63 = 4.50359962737049600000e+15,
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twom63 = 1.08420217248550443400e-19,
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huge = 1.0e+4900L,
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tiny = 1.0e-4900L;
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#ifdef __STDC__
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long double __scalbnl (long double x, int n)
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#else
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long double __scalbnl (x,n)
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long double x; int n;
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#endif
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{
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int32_t k,es,hx,lx;
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GET_LDOUBLE_WORDS(es,hx,lx,x);
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k = es&0x7fff; /* extract exponent */
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if (k==0) { /* 0 or subnormal x */
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if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
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x *= two63;
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GET_LDOUBLE_EXP(es,x);
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k = (hx&0x7fff) - 63;
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}
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if (k==0x7fff) return x+x; /* NaN or Inf */
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k = k+n;
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if (n> 50000 || k > 0x7ffe)
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return huge*__copysignl(huge,x); /* overflow */
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if (n< -50000)
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return tiny*__copysignl(tiny,x);
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if (k > 0) /* normal result */
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{SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
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if (k <= -63)
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return tiny*__copysignl(tiny,x); /*underflow*/
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k += 63; /* subnormal result */
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SET_LDOUBLE_EXP(x,(es&0x8000)|k);
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return x*twom63;
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}
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weak_alias (__scalbnl, scalbnl)
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