1/* s_scalbnl.c -- long double version of s_scalbn.c. 2 * Conversion to long double by Ulrich Drepper, 3 * Cygnus Support, drepper@cygnus.com. 4 */ 5 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) 18static char rcsid[] = "$NetBSD: $"; 19#endif 20 21/* 22 * scalbnl (long double x, int n) 23 * scalbnl(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 "math.h" 29#include "math_private.h" 30 31#ifdef __STDC__ 32static const long double 33#else 34static long double 35#endif 36two63 = 4.50359962737049600000e+15, 37twom63 = 1.08420217248550443400e-19, 38huge = 1.0e+4900L, 39tiny = 1.0e-4900L; 40 41#ifdef __STDC__ 42 long double __scalblnl (long double x, long int n) 43#else 44 long double __scalblnl (x,n) 45 long double x; long int n; 46#endif 47{ 48 int32_t k,es,hx,lx; 49 GET_LDOUBLE_WORDS(es,hx,lx,x); 50 k = es&0x7fff; /* extract exponent */ 51 if (k==0) { /* 0 or subnormal x */ 52 if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ 53 x *= two63; 54 GET_LDOUBLE_EXP(es,x); 55 k = (hx&0x7fff) - 63; 56 } 57 if (k==0x7fff) return x+x; /* NaN or Inf */ 58 k = k+n; 59 if (n> 50000 || k > 0x7ffe) 60 return huge*__copysignl(huge,x); /* overflow */ 61 if (n< -50000) 62 return tiny*__copysignl(tiny,x); 63 if (k > 0) /* normal result */ 64 {SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;} 65 if (k <= -63) 66 return tiny*__copysignl(tiny,x); /*underflow*/ 67 k += 63; /* subnormal result */ 68 SET_LDOUBLE_EXP(x,(es&0x8000)|k); 69 return x*twom63; 70} 71weak_alias (__scalblnl, scalblnl) 72