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66 lines
1.2 KiB
66 lines
1.2 KiB
#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 sa,sb,sc;
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void* p1(void *arg){
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int cnt=0;
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for(int i=0;i<30;i++){
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sem_wait(&sa);
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printf("A\n");
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cnt++;
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if(cnt%3==0){
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sem_post(&sb);
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}
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else{
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sem_post(&sa);
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}
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}
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}
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void* p2(void *arg){
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int cnt=0;
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for(int i=0;i<30;i++){
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sem_wait(&sb);
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printf("B\n");
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cnt++;
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if(cnt%3==0){
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sem_post(&sc);
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}
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else{
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sem_post(&sb);
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}
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}
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}
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void* p3(void *arg){
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int cnt=0;
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for(int i=0;i<30;i++){
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sem_wait(&sc);
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printf("C\n");
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cnt++;
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if(cnt%3==0){
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sem_post(&sa);
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}
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else{
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sem_post(&sc);
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}
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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(&sa,0,1);
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sem_init(&sb,0,0);
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sem_init(&sc,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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}
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