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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] =
"$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
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#endif
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#include "math.h"
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#include "mathP.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
00032 two54 = 1.80143985094819840000e+16,
00033 twom54 = 5.55111512312578270212e-17,
00034 huge = 1.0e+300,
00035 tiny = 1.0e-300;
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#ifdef __STDC__
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double scalbn (
double x,
int n)
00039 #
else
00040 double scalbn (x,n)
00041 double x;
int n;
00042 #endif
00043 {
00044 int32_t k,hx,lx;
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EXTRACT_WORDS(hx,lx,x);
00046 k = (hx&0x7ff00000)>>20;
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if (k==0) {
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if ((lx|(hx&0x7fffffff))==0)
return x;
00049 x *=
two54;
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GET_HIGH_WORD(hx,x);
00051 k = ((hx&0x7ff00000)>>20) - 54;
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if (n< -50000)
return tiny*x;
00053 }
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if (k==0x7ff)
return x+x;
00055 k = k+n;
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if (k > 0x7fe)
return huge*
copysign(huge,x);
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if (k > 0)
00058 {
SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
return x;}
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if (k <= -54) {
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if (n > 50000)
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return huge*
copysign(huge,x);
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else return tiny*
copysign(tiny,x);
00063 }
00064 k += 54;
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SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
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return x*twom54;
00067 }