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