mirror of https://github.com/PrimeDecomp/prime.git
58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
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/* @(#)s_frexp.c 1.3 95/01/04 */
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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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* for non-zero x
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* x = frexp(arg,&exp);
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* return a double fp quantity x such that 0.5 <= |x| <1.0
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* and the corresponding binary exponent "exp". That is
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* arg = x*2^exp.
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* If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
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* with *exp=0.
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*/
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#include "fdlibm.h"
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#ifdef __STDC__
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static const double
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#else
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static double
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#endif
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two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
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#ifdef __STDC__
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double frexp(double x, int* eptr)
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#else
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double frexp(x, eptr)
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double x;
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int* eptr;
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#endif
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{
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int hx, ix, lx;
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hx = __HI(x);
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ix = 0x7fffffff & hx;
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lx = __LO(x);
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*eptr = 0;
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if (ix >= 0x7ff00000 || ((ix | lx) == 0))
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return x; /* 0,inf,nan */
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if (ix < 0x00100000) { /* subnormal */
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x *= two54;
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hx = __HI(x);
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ix = hx & 0x7fffffff;
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*eptr = -54;
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}
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*eptr += (ix >> 20) - 1022;
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hx = (hx & 0x800fffff) | 0x3fe00000;
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__HI(x) = hx;
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return x;
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}
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