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comparison libquadmath/math/scalbnq.c @ 68:561a7518be6b

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update gcc-4.6
author Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
date Sun, 21 Aug 2011 07:07:55 +0900
parents
children 04ced10e8804
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67:f6334be47118 68:561a7518be6b
1 /* s_scalbnl.c -- long double version of s_scalbn.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
3 */
4
5 /*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16 #include "quadmath-imp.h"
17
18 static const __float128
19 two114 = 2.0769187434139310514121985316880384E+34Q, /* 0x4071000000000000, 0 */
20 twom114 = 4.8148248609680896326399448564623183E-35Q, /* 0x3F8D000000000000, 0 */
21 huge = 1.0E+4900Q,
22 tiny = 1.0E-4900Q;
23
24 __float128
25 scalbnq (__float128 x, int n)
26 {
27 int64_t k,hx,lx;
28 GET_FLT128_WORDS64(hx,lx,x);
29 k = (hx>>48)&0x7fff; /* extract exponent */
30 if (k==0) { /* 0 or subnormal x */
31 if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */
32 x *= two114;
33 GET_FLT128_MSW64(hx,x);
34 k = ((hx>>48)&0x7fff) - 114;
35 }
36 if (k==0x7fff) return x+x; /* NaN or Inf */
37 k = k+n;
38 if (n> 50000 || k > 0x7ffe)
39 return huge*copysignq(huge,x); /* overflow */
40 if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
41 if (k > 0) /* normal result */
42 {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;}
43 if (k <= -114)
44 return tiny*copysignq(tiny,x); /*underflow*/
45 k += 114; /* subnormal result */
46 SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48));
47 return x*twom114;
48 }