43 lines
983 B
C
43 lines
983 B
C
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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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// WOW, new word: it means the compiler is not allowed to optimize this varible
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volatile int counter = 0;
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void* mythread(void* arg) {
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char* letter = arg;
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int i;
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printf("%s: begin [addr of i: %p]\n", letter, (void*) &i);
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for (i = 0; i < max; i++) {
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counter = counter + 1;
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}
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printf("%s: done with counter at %d\n", letter, counter);
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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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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", counter, max * 2);
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return 0;
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}
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