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