56 lines
1008 B
C
56 lines
1008 B
C
#include <stdio.h>
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#include <stdlib.h>
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#include <pthread.h>
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#include <unistd.h>
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#include "common.h"
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#include "common_threads.h"
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typedef struct __Zem_t {
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int value;
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pthread_cond_t cond;
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pthread_mutex_t lock;
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} Zem_t;
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void Zem_init(Zem_t *z, int value) {
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z->value = value;
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Cond_init(&z->cond);
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Mutex_init(&z->lock);
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}
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void Zem_wait(Zem_t *z) {
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Mutex_lock(&z->lock);
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while (z->value <= 0)
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Cond_wait(&z->cond, &z->lock);
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z->value--;
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Mutex_unlock(&z->lock);
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}
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void Zem_post(Zem_t *z) {
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Mutex_lock(&z->lock);
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z->value++;
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Cond_signal(&z->cond);
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Mutex_unlock(&z->lock);
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}
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Zem_t s;
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void *child(void *arg) {
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sleep(4);
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printf("child\n");
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Zem_post(&s); // signal here: child is done
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return NULL;
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}
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int main(int argc, char *argv[]) {
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Zem_init(&s, 0);
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printf("parent: begin\n");
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pthread_t c;
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Pthread_create(&c, NULL, child, NULL);
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Zem_wait(&s); // wait here for child
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printf("parent: end\n");
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return 0;
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}
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