Question about #define

Rabbit
1

Hi there,

I have been programming using DC 8.51 on RCM 3100 for some time. I usually hardcode the values for #defines. I was trying to do bitwise operation for #define e.g. #define SESSION_B SESSION_A | SESSION_ONLINE. When SESSION_B is compared to any value, it always yields TRUE (see sample code below).

Does DC not support this operation? or does it do some implicit conversion? or did I do anything wrong?

////////////////////////////////////////////////////////////

/*** Beginheader */
#define SESSION_OFFLINE 0
#define SESSION_ONLINE 1

#define SESSION_A 2
#define SESSION_B SESSION_A | SESSION_ONLINE
/*** endheader */

/*** BeginHeader main /
xmem void main( void );
/** endheader */

xmem void main()
{
int i;

// SESSION_B is 3
for( i = 0; i < 10; i++ )
{
    if( i == SESSION_B )
   	printf("TRUE i = %d, SESSION_B = %d

", i, SESSION_B );
else
printf(“FALSE”);
}
}
//////////////////////////////////////////////////////////

The results were:
TRUE i = 0, SESSION_B = 3
TRUE i = 1, SESSION_B = 3
TRUE i = 2, SESSION_B = 3
TRUE i = 3, SESSION_B = 3
TRUE i = 4, SESSION_B = 3
TRUE i = 5, SESSION_B = 3
TRUE i = 6, SESSION_B = 3
TRUE i = 7, SESSION_B = 3
TRUE i = 8, SESSION_B = 3
TRUE i = 9, SESSION_B = 3

TIA,
Andy

2

try using
#define SESSION_B (SESSION_A | SESSION_ONLINE)

the way you defined it, line
if( i == SESSION_B )
is substituted with
if( i == SESSION_A | SESSION_ONLINE)
and the == operator has greater priority than | operator, so the line you wrote means
if ( (i == 2) | 1)
->
if ( 0 | 1)
->
if ( 1 )
…

Luka

3

Thanks to everyone who replied.