1/* scalbnq.c -- __float128 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
17/*
18 * scalbnq (__float128 x, int n)
19 * scalbnq(x,n) returns x* 2**n  computed by  exponent
20 * manipulation rather than by actually performing an
21 * exponentiation or a multiplication.
22 */
23
24#include "quadmath-imp.h"
25
26static const __float128
27two114 = 2.0769187434139310514121985316880384E+34Q, /* 0x4071000000000000, 0 */
28twom114 = 4.8148248609680896326399448564623183E-35Q, /* 0x3F8D000000000000, 0 */
29huge   = 1.0E+4900Q,
30tiny   = 1.0E-4900Q;
31
32__float128
33scalbnq (__float128 x, int n)
34{
35	int64_t k,hx,lx;
36	GET_FLT128_WORDS64(hx,lx,x);
37        k = (hx>>48)&0x7fff;		/* extract exponent */
38        if (k==0) {				/* 0 or subnormal x */
39            if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */
40	    x *= two114;
41	    GET_FLT128_MSW64(hx,x);
42	    k = ((hx>>48)&0x7fff) - 114;
43	}
44        if (k==0x7fff) return x+x;		/* NaN or Inf */
45	if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
46        if (n> 50000 || k+n > 0x7ffe)
47	  return huge*copysignq(huge,x); /* overflow  */
48	/* Now k and n are bounded we know that k = k+n does not
49	   overflow.  */
50        k = k+n;
51        if (k > 0) 				/* normal result */
52	    {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;}
53        if (k <= -114)
54	  return tiny*copysignq(tiny,x); 	/*underflow*/
55        k += 114;				/* subnormal result */
56	SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48));
57        return x*twom114;
58}
59