diff options
Diffstat (limited to 'third_party/js-1.7/fdlibm/s_scalbn.c')
| -rw-r--r-- | third_party/js-1.7/fdlibm/s_scalbn.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/third_party/js-1.7/fdlibm/s_scalbn.c b/third_party/js-1.7/fdlibm/s_scalbn.c new file mode 100644 index 0000000..3deeaa3 --- /dev/null +++ b/third_party/js-1.7/fdlibm/s_scalbn.c @@ -0,0 +1,107 @@ +/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- + * + * ***** BEGIN LICENSE BLOCK ***** + * Version: MPL 1.1/GPL 2.0/LGPL 2.1 + * + * The contents of this file are subject to the Mozilla Public License Version + * 1.1 (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * Software distributed under the License is distributed on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License + * for the specific language governing rights and limitations under the + * License. + * + * The Original Code is Mozilla Communicator client code, released + * March 31, 1998. + * + * The Initial Developer of the Original Code is + * Sun Microsystems, Inc. + * Portions created by the Initial Developer are Copyright (C) 1998 + * the Initial Developer. All Rights Reserved. + * + * Contributor(s): + * + * Alternatively, the contents of this file may be used under the terms of + * either of the GNU General Public License Version 2 or later (the "GPL"), + * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), + * in which case the provisions of the GPL or the LGPL are applicable instead + * of those above. If you wish to allow use of your version of this file only + * under the terms of either the GPL or the LGPL, and not to allow others to + * use your version of this file under the terms of the MPL, indicate your + * decision by deleting the provisions above and replace them with the notice + * and other provisions required by the GPL or the LGPL. If you do not delete + * the provisions above, a recipient may use your version of this file under + * the terms of any one of the MPL, the GPL or the LGPL. + * + * ***** END LICENSE BLOCK ***** */ + +/* @(#)s_scalbn.c 1.3 95/01/18 */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunSoft, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* + * scalbn (double x, int n) + * scalbn(x,n) returns x* 2**n computed by exponent + * manipulation rather than by actually performing an + * exponentiation or a multiplication. + */ + +#include "fdlibm.h" + +#ifdef __STDC__ +static const double +#else +static double +#endif +two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ +twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ +really_big = 1.0e+300, +tiny = 1.0e-300; + +#ifdef __STDC__ + double fd_scalbn (double x, int n) +#else + double fd_scalbn (x,n) + double x; int n; +#endif +{ + fd_twoints u; + int k,hx,lx; + u.d = x; + hx = __HI(u); + lx = __LO(u); + k = (hx&0x7ff00000)>>20; /* extract exponent */ + if (k==0) { /* 0 or subnormal x */ + if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ + x *= two54; + u.d = x; + hx = __HI(u); + k = ((hx&0x7ff00000)>>20) - 54; + if (n< -50000) return tiny*x; /*underflow*/ + } + if (k==0x7ff) return x+x; /* NaN or Inf */ + k = k+n; + if (k > 0x7fe) return really_big*fd_copysign(really_big,x); /* overflow */ + if (k > 0) /* normal result */ + {u.d = x; __HI(u) = (hx&0x800fffff)|(k<<20); x = u.d; return x;} + if (k <= -54) { + if (n > 50000) /* in case integer overflow in n+k */ + return really_big*fd_copysign(really_big,x); /*overflow*/ + else return tiny*fd_copysign(tiny,x); /*underflow*/ + } + k += 54; /* subnormal result */ + u.d = x; + __HI(u) = (hx&0x800fffff)|(k<<20); + x = u.d; + return x*twom54; +} |