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add fdlibm

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git-svn-id: http://svn2.nishi.boats/svn/milsko/trunk@557 b9cfdab3-6d41-4d17-bbe4-086880011989
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Nishi 2025-11-01 15:48:47 +00:00
commit 7f523a3d76
90 changed files with 7325 additions and 309 deletions
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57
external/fdlibm/s_scalbn.c vendored Normal file
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/* @(#)s_scalbn.c 1.3 95/01/18 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* scalbn (double x, int n)
* scalbn(x,n) returns x* 2**n computed by exponent
* manipulation rather than by actually performing an
* exponentiation or a multiplication.
*/
#include "math.h"
static const double
two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
hugev = 1.0e+300,
tinyv = 1.0e-300;
double scalbn(double x, int n) {
int k, hx, lx;
hx = __HI(x);
lx = __LO(x);
k = (hx & 0x7ff00000) >> 20; /* extract exponent */
if(k == 0) { /* 0 or subnormal x */
if((lx | (hx & 0x7fffffff)) == 0) return x; /* +-0 */
x *= two54;
hx = __HI(x);
k = ((hx & 0x7ff00000) >> 20) - 54;
if(n < -50000) return tinyv * x; /*underflow*/
}
if(k == 0x7ff) return x + x; /* NaN or Inf */
k = k + n;
if(k > 0x7fe) return hugev * copysign(hugev, x); /* overflow */
if(k > 0) /* normal result */
{
__HI(x) = (hx & 0x800fffff) | (k << 20);
return x;
}
if(k <= -54)
if(n > 50000) /* in case integer overflow in n+k */
return hugev * copysign(hugev, x); /*overflow*/
else
return tinyv * copysign(tinyv, x); /*underflow*/
k += 54; /* subnormal result */
__HI(x) = (hx & 0x800fffff) | (k << 20);
return x * twom54;
}