1*627f7eb2Smrg /* s_scalbnl.c -- long double version of s_scalbn.c.
2*627f7eb2Smrg * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
3*627f7eb2Smrg */
4*627f7eb2Smrg
5*627f7eb2Smrg /* @(#)s_scalbn.c 5.1 93/09/24 */
6*627f7eb2Smrg /*
7*627f7eb2Smrg * ====================================================
8*627f7eb2Smrg * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9*627f7eb2Smrg *
10*627f7eb2Smrg * Developed at SunPro, a Sun Microsystems, Inc. business.
11*627f7eb2Smrg * Permission to use, copy, modify, and distribute this
12*627f7eb2Smrg * software is freely granted, provided that this notice
13*627f7eb2Smrg * is preserved.
14*627f7eb2Smrg * ====================================================
15*627f7eb2Smrg */
16*627f7eb2Smrg
17*627f7eb2Smrg #if defined(LIBM_SCCS) && !defined(lint)
18*627f7eb2Smrg static char rcsid[] = "NetBSD: ";
19*627f7eb2Smrg #endif
20*627f7eb2Smrg
21*627f7eb2Smrg /*
22*627f7eb2Smrg * scalbnq (long double x, int n)
23*627f7eb2Smrg * scalbnq(x,n) returns x* 2**n computed by exponent
24*627f7eb2Smrg * manipulation rather than by actually performing an
25*627f7eb2Smrg * exponentiation or a multiplication.
26*627f7eb2Smrg */
27*627f7eb2Smrg
28*627f7eb2Smrg #include "quadmath-imp.h"
29*627f7eb2Smrg
30*627f7eb2Smrg static const __float128
31*627f7eb2Smrg two114 = 2.0769187434139310514121985316880384E+34Q, /* 0x4071000000000000, 0 */
32*627f7eb2Smrg twom114 = 4.8148248609680896326399448564623183E-35Q, /* 0x3F8D000000000000, 0 */
33*627f7eb2Smrg huge = 1.0E+4900Q,
34*627f7eb2Smrg tiny = 1.0E-4900Q;
35*627f7eb2Smrg
scalbnq(__float128 x,int n)36*627f7eb2Smrg __float128 scalbnq (__float128 x, int n)
37*627f7eb2Smrg {
38*627f7eb2Smrg int64_t k,hx,lx;
39*627f7eb2Smrg GET_FLT128_WORDS64(hx,lx,x);
40*627f7eb2Smrg k = (hx>>48)&0x7fff; /* extract exponent */
41*627f7eb2Smrg if (k==0) { /* 0 or subnormal x */
42*627f7eb2Smrg if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */
43*627f7eb2Smrg x *= two114;
44*627f7eb2Smrg GET_FLT128_MSW64(hx,x);
45*627f7eb2Smrg k = ((hx>>48)&0x7fff) - 114;
46*627f7eb2Smrg }
47*627f7eb2Smrg if (k==0x7fff) return x+x; /* NaN or Inf */
48*627f7eb2Smrg if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
49*627f7eb2Smrg if (n> 50000 || k+n > 0x7ffe)
50*627f7eb2Smrg return huge*copysignq(huge,x); /* overflow */
51*627f7eb2Smrg /* Now k and n are bounded we know that k = k+n does not
52*627f7eb2Smrg overflow. */
53*627f7eb2Smrg k = k+n;
54*627f7eb2Smrg if (k > 0) /* normal result */
55*627f7eb2Smrg {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;}
56*627f7eb2Smrg if (k <= -114)
57*627f7eb2Smrg return tiny*copysignq(tiny,x); /*underflow*/
58*627f7eb2Smrg k += 114; /* subnormal result */
59*627f7eb2Smrg SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48));
60*627f7eb2Smrg return x*twom114;
61*627f7eb2Smrg }
62