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47 lines
1006 B
47 lines
1006 B
#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 <sys/types.h>
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#include <semaphore.h>
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sem_t pa,pb,pc;
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void* p1(void *arg){
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for(int i=0;i<10;i++){
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sem_wait(&pa);
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usleep(1000*1000/2);
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printf("A\n");
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sem_post(&pb);
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}
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}
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void* p2(void *arg){
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for(int i=0;i<10;i++){
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sem_wait(&pb);
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usleep(1000*1000/2);
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printf("B\n");
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sem_post(&pc);
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}
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}
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void* p3(void *arg){
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for(int i=0;i<10;i++){
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sem_wait(&pc);
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printf("C\n");
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usleep(1000*1000/2);
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sem_post(&pa);
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}
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}
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int main()
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{
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pthread_t tid[3];
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sem_init(&pa,0,1);
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sem_init(&pb,0,0);
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sem_init(&pc,0,0);
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pthread_create(&tid[0], NULL, p1, NULL);
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pthread_create(&tid[1], NULL, p2, NULL);
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pthread_create(&tid[2], NULL, p3, NULL);
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for(int i = 0; i < 3; i++)
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pthread_join(tid[i], NULL);
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printf("main is over\n");
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return 0;
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}
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