62 lines
1.1 KiB
C
62 lines
1.1 KiB
C
#include <pthread.h>
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#include <time.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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int cnt = 0;
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sem_t mutex;
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void *increase(void *vargp)
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{
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unsigned int niters = (unsigned int)vargp;
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for (unsigned int i = 0; i < niters; i++)
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{
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sem_wait(&mutex);
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cnt++;
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sem_post(&mutex);
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}
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return NULL;
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}
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void *decrease(void *vargp)
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{
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unsigned int niters = (unsigned int)vargp;
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for (unsigned int i = 0; i < niters; i++)
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{
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sem_wait(&mutex);
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cnt--;
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sem_post(&mutex);
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}
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return NULL;
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}
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int main(int argc, char **argv)
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{
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unsigned int niters;
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pthread_t t1,t2;
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if (argc != 2)
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{
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printf("Usage: %s <niters>\n", argv[0]);
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exit(2);
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}
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niters = atoll(argv[1]);
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sem_init(&mutex, 0, 1);
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pthread_create(&t1,NULL,increase,(void*)niters);
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pthread_create(&t2,NULL,decrease,(void*)niters);
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pthread_join(t1,NULL);
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pthread_join(t2,NULL);
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if (cnt != 0)
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{
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printf("Error! cnt=%d\n", cnt);
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}
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else
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{
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printf("Correct! cnt=%d\n", cnt);
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}
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sem_destroy(&mutex);
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exit(0);
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} |