ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / s_frexp.c
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74dfd0cf 1/* @(#)s_frexp.c 5.1 93/09/24 */
6ff43c94 2/* $FreeBSD: head/lib/msun/src/s_frexp.c 176451 2008-02-22 02:30:36Z das $ */
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3/*
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 *
7 * Developed at SunPro, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
10 * is preserved.
11 * ====================================================
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12 */
13
14/*
15 * for non-zero x
16 * x = frexp(arg,&exp);
17 * return a double fp quantity x such that 0.5 <= |x| <1.0
18 * and the corresponding binary exponent "exp". That is
19 * arg = x*2^exp.
20 * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
21 * with *exp=0.
22 */
23
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24#include <float.h>
25
26#include "math.h"
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27#include "math_private.h"
28
29static const double
30two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
31
32double
33frexp(double x, int *eptr)
34{
35 int32_t hx, ix, lx;
36 EXTRACT_WORDS(hx,lx,x);
37 ix = 0x7fffffff&hx;
38 *eptr = 0;
39 if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */
40 if (ix<0x00100000) { /* subnormal */
41 x *= two54;
42 GET_HIGH_WORD(hx,x);
43 ix = hx&0x7fffffff;
44 *eptr = -54;
45 }
6ff43c94 46 *eptr += (ix>>20)-1022;
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47 hx = (hx&0x800fffff)|0x3fe00000;
48 SET_HIGH_WORD(x,hx);
49 return x;
50}
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51
52#if (LDBL_MANT_DIG == 53)
53__weak_reference(frexp, frexpl);
54#endif