How to deal with flag variables in embedded system -

i doing project on embedded system changing flag variable 'x_flag' upon interrupt. flag variable global , accessed in other source files check state of condition of events too.

i know troubles dealing global variables, ask how can access current state of 'x_flag' in other source files?

in c-file can define like

volatile int x_flag;  void myisrfunction(void) {     x_flag = 1; } 

and in header file add declaration

extern volatile int x_flag; 

then need include header file other c-file able access x_flag

but there should disable interrupt when accessing/modifing flag.

#include "myisr.h"  void somefunc() {   int local_x_flag;    disableinterrupts();   local_x_flag = x_flag;   x_flag = 0;   enableinterrupts();    if ( local_x_flag )     dosomething(); } 

note if flag hardware register, may need more careful, disabling interrupts not stop hardware altering value of flag , clearing explicitly may or may not allowed. in case, you'll need @ hardware documentation find out , not safe (and/or talk whoever designing it, if you're working hardware engineers).