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