/*
Program that is replacement for finite()

Description

This function checks if a number is finite. It determines if the passed 
floating point number represents an overflow condition.

If the exponent of an AS/400 double (which is 8 byte) is all 1's and 
fraction is all 0's then it is infinite. Bits in an AS/400 double are:

           0     sign
           1:11  exponent
           12:63 fraction
                                                                    
Bit 0 is the leftmost bit.

Choose your browser's option to 'save to local disk' and then reload this 
document to download this code example.  Send the program to your AS/400 
and compile it using the development facilities supplied there.  This 
program was developed on a V3R6 system and tested on V3R1, V3R2 and V3R6 
systems.

This small program that is furnished by IBM is a simple example to provide 
an illustration.  This example has not been thoroughly tested under all 
conditions.  IBM, therefore, cannot guarantee or imply reliability, 
serviceability, or function of this program.  All programs contained herein 
are provided to you "AS IS".  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 
FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY DISCLAIMED.

 */
/************************************************************************/
/*                                                                      */
/* test case:    finite.c                                               */
/*                                                                      */
/* objective:    finite() workaround                                    */
/*                                                                      */
/* usage notes:  Compile this program using CRTCMOD and then bind the   */
/*               module with other modules using finite() to create     */
/*               program object.                                        */
/*                                                                      */
/************************************************************************/

#include <stdio.h>

typedef struct {
    unsigned long lobits;
    unsigned long hibits;
    } BITMASK;

typedef union {
    BITMASK bm;
    double  dv;
    } OVERLAY;

#define EXPBITS  0x7FF00000
#define ALLZEROS 0x00000000
#define CHKEXP   0x000FFFFF


int finite( double fres ) {

    OVERLAY value;

    value.dv = fres;
    if ( ( (value.bm.lobits & EXPBITS) == EXPBITS )  &&
		 ( (value.bm.lobits & CHKEXP)  == ALLZEROS ) &&
		 ( value.bm.hibits == ALLZEROS ) )
        return( 0 ); /* No, it is not a finite number */
    else 
		return( 1 ); /* it is a finite number */
}