1 /* s_scalblnl.c -- long double version of s_scalbn.c. 2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@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 * scalblnl (long double x, long int n) 23 * scalblnl(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 scalblnq (__float128 x, long 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