pow87e.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 75 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
*    ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
*    NON-INFRINGEMENT. Please see the License for the specific language
*    governing rights and limitations under the License.
*
*  ========================================================================
*
* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
*               DESCRIBE IT HERE!
*
****************************************************************************/


#include "variety.h"
#include <stddef.h>
#include <math.h>
#include "mathcode.h"

#if defined(__386__) && defined(__SW_3S)
   #pragma aux __pow87_err parm [] modify []
#endif


double __pow87_err( double x, double y, unsigned char code )
/**********************************************************/
{
    unsigned int err_code;

    if( code <= 1 ) {
        if( code == 0 ) {           /* x == 0.0  */
            if( y > 0.0 )  return( 0.0 );
            if( y < 0.0 ) {
//                    result = HUGE_VAL;
                err_code = FUNC_POW | M_DOMAIN | V_HUGEVAL; /* 0.0 ** -ve */
            } else {
//                    result = 1.0;
                err_code = FUNC_POW | M_DOMAIN | V_ONE;     /* 0.0 ** 0.0 */
            }
        } else {                    /* negative ** fraction  */
            err_code = FUNC_POW | M_DOMAIN | V_ZERO;        /* -ve ** frac*/
        }
//            result = _matherr( DOMAIN, "pow", &x, &y, result );
        return( __math2err( err_code, &x, &y ) );
    } else {        /* code == 2 */
        if( y <= 0.0 )  return( 0.0 );                      /* 27-may-90 */
//            result = (x > 0.0) ? HUGE_VAL : - HUGE_VAL;
//            result = _matherr( OVERFLOW, "pow", &x, &y, result );
        if( x > 0.0 ) {
            err_code = FUNC_POW | M_OVERFLOW | V_HUGEVAL;
        } else {
            err_code = FUNC_POW | M_OVERFLOW | V_NEG_HUGEVAL;
        }
        return( __math2err( err_code, &x, &y ) );
    }
}