65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
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/* s_ilogbl.c -- long double version of s_ilogb.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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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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) = FP_ILOGB0
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* ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
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* ilogbl(+-Inf) = INT_MAX (no signal is raised)
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*/
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#include <limits.h>
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#include <math.h>
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#include "quadmath-imp.h"
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#ifndef FP_ILOGB0
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# define FP_ILOGB0 INT_MIN
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#endif
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#ifndef FP_ILOGBNAN
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# define FP_ILOGBNAN INT_MAX
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#endif
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int
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ilogbq (__float128 x)
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{
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int64_t hx,lx;
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int ix;
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GET_FLT128_WORDS64(hx,lx,x);
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hx &= 0x7fffffffffffffffLL;
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if(hx <= 0x0001000000000000LL) {
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if((hx|lx)==0)
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return FP_ILOGB0; /* ilogbl(0) = FP_ILOGB0 */
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else /* subnormal x */
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if(hx==0) {
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for (ix = -16431; lx>0; lx<<=1) ix -=1;
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} else {
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for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1;
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}
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return ix;
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}
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else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
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else if (FP_ILOGBNAN != INT_MAX) {
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/* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */
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if (((hx^0x7fff000000000000LL)|lx) == 0)
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return INT_MAX;
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}
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return FP_ILOGBNAN;
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}
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