- #include <windows.h>
- Critical_Section cs;
- InitializeCriticalSection( &cs); /* setup binary semaphore */
- EnterCriticalSection( &cs);
- LeaveCriticalSection( &cs);
- DeleteCriticalSection( &cs);
EXAMPLE:
- #include <stdio.h>
#include <stdlib.h> /* rand() */
#include <process.h> /* _beginthread */
#include <windows.h> /* CRITICAL_SECTION */
#include <conio.h> /* _getch() */
#define GetRandom( min, max ) ((rand() % (int)(((max) + 1) - (min))) + (min))
#define N ( (int)100)
#define PROTECTED 0 /* yes==1, no==0 */
#if PROTECTED
CRITICAL_SECTION cs;
#endif
int counter=0; /* shared variable */
bool wait=true;
void CPU( void * delta) /* simulate a two register CPU */
{
register int reg1, reg2;
#if PROTECTED
EnterCriticalSection( &cs); /* option to lock area */
#endif
reg1 = (int) delta; /* cpu register 1 <- copy delta */
reg2 = counter; /* cpu register 2 <- copy counter */
Sleep( GetRandom(0,10) ); /* simulate random interruts of CPU */
reg2 = reg2 + reg1; /* register-register addition */
counter = reg2; /* copy register to RAM */
#if PROTECTED
LeaveCriticalSection( &cs); /* option to unlock area */
#endif
printf("count is %d\n", counter);
}
void CheckKey( void *dummy ) /* deamon process to look for a pressed */
{ /* key, any key. */
_getch();
wait = false;
}
void main() {
int i, sum = (N*(N-1))/2;
#if PROTECTED
InitializeCriticalSection( &cs); /* setup binary semaphore */
#endif
_beginthread(CheckKey, 0, NULL); /* start background thread */
for(i=0; i<N; i++)
_beginthread(CPU, 0, (void *) i); /* give each CPU marching orders */
while (wait ) /* check if deamon has found a pressed key */
Sleep(100L); /* take a nap between ... */
printf("totla should be %d, and is computed as %d\n", sum, counter);
}