w_pow.c

ecos实时嵌入式操作系统

//========================================================================
//
//      w_pow.c
//
//      Part of the standard mathematical function library
//
//========================================================================
//####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
//
// eCos is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 or (at your option) any later version.
//
// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with eCos; if not, write to the Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or inline functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
// by itself cause the resulting work to be covered by the GNU General Public
// License. However the source code for this file must still be made available
// in accordance with section (3) of the GNU General Public License.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):     jlarmour
// Contributors:  jlarmour
// Date:          1998-02-13
// Purpose:     
// Description: 
// Usage:       
//
//####DESCRIPTIONEND####
//
//========================================================================

// CONFIGURATION

#include <pkgconf/libm.h>   // Configuration header

// Include the Math library?
#ifdef CYGPKG_LIBM     

// Derived from code with the following copyright



/* @(#)w_pow.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.
 * ====================================================
 */

/* 
 * wrapper pow(x,y) return x**y
 */

#include "mathincl/fdlibm.h"


        double pow(double x, double y)  /* wrapper pow */
{
#ifdef CYGSEM_LIBM_COMPAT_IEEE_ONLY
        return  __ieee754_pow(x,y);
#else
        double z;
        z=__ieee754_pow(x,y);
        if(cyg_libm_get_compat_mode() == CYGNUM_LIBM_COMPAT_IEEE||
           isnan(y))
            return z;
        if(isnan(x)) {
            if(y==0.0) 
                return __kernel_standard(x,y,42); /* pow(NaN,0.0) */
            else 
                return z;
        }
        if(x==0.0){ 
            if(y==0.0)
                return __kernel_standard(x,y,20); /* pow(0.0,0.0) */
            if(finite(y)&&y<0.0)
                return __kernel_standard(x,y,23); /* pow(0.0,negative) */
            return z;
        }
        if(!finite(z)) {
            if(finite(x)&&finite(y)) {
                if(isnan(z))
                    return __kernel_standard(x,y,24);/* pow neg**non-int */
                else 
                    return __kernel_standard(x,y,21); /* pow overflow */
            }
        } 
        if(z==0.0&&finite(x)&&finite(y))
            return __kernel_standard(x,y,22); /* pow underflow */
        return z;
#endif
}

#endif // ifdef CYGPKG_LIBM     

// EOF w_pow.c