/* s_scalblnl.c -- long double version of s_scalbn.c. * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. */ /* @(#)s_scalbn.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #if defined(LIBM_SCCS) && !defined(lint) static char rcsid[] = "NetBSD: "; #endif /* * scalblnl (long double x, long int n) * scalblnl(x,n) returns x* 2**n computed by exponent * manipulation rather than by actually performing an * exponentiation or a multiplication. */ #include "quadmath-imp.h" static const __float128 two114 = 2.0769187434139310514121985316880384E+34Q, /* 0x4071000000000000, 0 */ twom114 = 4.8148248609680896326399448564623183E-35Q, /* 0x3F8D000000000000, 0 */ huge = 1.0E+4900Q, tiny = 1.0E-4900Q; __float128 scalblnq (__float128 x, long int n) { int64_t k,hx,lx; GET_FLT128_WORDS64(hx,lx,x); k = (hx>>48)&0x7fff; /* extract exponent */ if (k==0) { /* 0 or subnormal x */ if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */ x *= two114; GET_FLT128_MSW64(hx,x); k = ((hx>>48)&0x7fff) - 114; } if (k==0x7fff) return x+x; /* NaN or Inf */ if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/ if (n> 50000 || k+n > 0x7ffe) return huge*copysignq(huge,x); /* overflow */ /* Now k and n are bounded we know that k = k+n does not overflow. */ k = k+n; if (k > 0) /* normal result */ {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;} if (k <= -114) return tiny*copysignq(tiny,x); /*underflow*/ k += 114; /* subnormal result */ SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x*twom114; } |