1 //===========================================================================
5 // Part of the standard mathematical function library
7 //===========================================================================
8 //####ECOSGPLCOPYRIGHTBEGIN####
9 // -------------------------------------------
10 // This file is part of eCos, the Embedded Configurable Operating System.
11 // Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
13 // eCos is free software; you can redistribute it and/or modify it under
14 // the terms of the GNU General Public License as published by the Free
15 // Software Foundation; either version 2 or (at your option) any later version.
17 // eCos is distributed in the hope that it will be useful, but WITHOUT ANY
18 // WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
22 // You should have received a copy of the GNU General Public License along
23 // with eCos; if not, write to the Free Software Foundation, Inc.,
24 // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
26 // As a special exception, if other files instantiate templates or use macros
27 // or inline functions from this file, or you compile this file and link it
28 // with other works to produce a work based on this file, this file does not
29 // by itself cause the resulting work to be covered by the GNU General Public
30 // License. However the source code for this file must still be made available
31 // in accordance with section (3) of the GNU General Public License.
33 // This exception does not invalidate any other reasons why a work based on
34 // this file might be covered by the GNU General Public License.
36 // Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
37 // at http://sources.redhat.com/ecos/ecos-license/
38 // -------------------------------------------
39 //####ECOSGPLCOPYRIGHTEND####
40 //===========================================================================
41 //#####DESCRIPTIONBEGIN####
43 // Author(s): jlarmour
44 // Contributors: jlarmour
50 //####DESCRIPTIONEND####
52 //===========================================================================
56 #include <pkgconf/libm.h> // Configuration header
58 // Include the Math library?
61 // Derived from code with the following copyright
64 /* @(#)s_scalbn.c 1.3 95/01/18 */
66 * ====================================================
67 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
69 * Developed at SunSoft, a Sun Microsystems, Inc. business.
70 * Permission to use, copy, modify, and distribute this
71 * software is freely granted, provided that this notice
73 * ====================================================
77 * scalbn (double x, int n)
78 * scalbn(x,n) returns x* 2**n computed by exponent
79 * manipulation rather than by actually performing an
80 * exponentiation or a multiplication.
83 #include "mathincl/fdlibm.h"
86 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
87 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
91 double scalbn (double x, int n)
96 k = (hx&0x7ff00000)>>20; /* extract exponent */
97 if (k==0) { /* 0 or subnormal x */
98 if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
101 k = ((hx&0x7ff00000)>>20) - 54;
102 if (n< -50000) return tiny*x; /*underflow*/
104 if (k==0x7ff) return x+x; /* NaN or Inf */
106 if (k > 0x7fe) return huge*copysign(huge,x); /* overflow */
107 if (k > 0) /* normal result */
108 {CYG_LIBM_HI(x) = (hx&0x800fffff)|(k<<20); return x;}
110 if (n > 50000) /* in case integer overflow in n+k */
111 return huge*copysign(huge,x); /*overflow*/
112 else return tiny*copysign(tiny,x); /*underflow*/
114 k += 54; /* subnormal result */
115 CYG_LIBM_HI(x) = (hx&0x800fffff)|(k<<20);
119 #endif // ifdef CYGPKG_LIBM