42 lines
1.1 KiB
C
42 lines
1.1 KiB
C
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <pthread.h>
|
|
|
|
#include "common.h"
|
|
#include "common_threads.h"
|
|
|
|
int max;
|
|
volatile int counter = 0; // shared global variable
|
|
|
|
void *mythread(void *arg) {
|
|
char *letter = arg;
|
|
int i; // stack (private per thread)
|
|
printf("%s: begin [addr of i: %p]\n", letter, &i);
|
|
for (i = 0; i < max; i++) {
|
|
counter = counter + 1; // shared: only one
|
|
}
|
|
printf("%s: done\n", letter);
|
|
return NULL;
|
|
}
|
|
|
|
int main(int argc, char *argv[]) {
|
|
if (argc != 2) {
|
|
fprintf(stderr, "usage: main-first <loopcount>\n");
|
|
exit(1);
|
|
}
|
|
max = atoi(argv[1]);
|
|
|
|
pthread_t p1, p2;
|
|
printf("main: begin [counter = %d] [%x]\n", counter,
|
|
(unsigned int) &counter);
|
|
Pthread_create(&p1, NULL, mythread, "A");
|
|
Pthread_create(&p2, NULL, mythread, "B");
|
|
// join waits for the threads to finish
|
|
Pthread_join(p1, NULL);
|
|
Pthread_join(p2, NULL);
|
|
printf("main: done\n [counter: %d]\n [should: %d]\n",
|
|
counter, max*2);
|
|
return 0;
|
|
}
|
|
|