Simple multi-threaded application explains how to create apps with multiple threads and also explains about how to deal with args parameter of pthread_create

test_lpthread.c

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdint.h>
#include <sys/time.h>

#define VP void*
#define NTH 2

int fdw32 = 0;
int fdr32 = 0;

int N = 0;
int i;

int *array_input;
int *array_hardware;

struct timeval tv1,tv2;
ssize_t w,e,r;

VP sample_1(VP arg);
VP sample_2(VP arg);

VP sample_1(VP arg) {
	w = write(fdw32, array_input, sizeof(int)*N);
	e = write(fdw32, NULL, 0);
	pthread_exit(NULL);
}

VP sample_2(VP arg) {
        r = read(fdr32, array_hardware, sizeof(int)*N);
        pthread_exit(NULL);
}


//int main(void)
int main(int argc, char *argv[])
{
        fdw32 = open("/dev/xillybus_write_32", O_WRONLY);
        fdr32 = open("/dev/xillybus_read_32", O_RDONLY);

	N = atoi(argv[1]);
	//N = N*4;

        if (fdw32<0 || fdr32<0) {
                perror("Failed to open devfiles");
                exit(1);
        }
	
	//printf("sizeof(short) = %d\r\n", sizeof(short));
	//printf("sizeof(int) = %d\r\n", sizeof(int));

        //allocate memory
        array_input = (int*) malloc(N*sizeof(int));
        array_hardware = (int*) malloc(N*sizeof(int));

        // generate inputs and prepare outputs
        for(i=0; i<N; i++){
                array_input[i] = i;
                array_hardware[i] = 0;
        }

	pthread_t tid[NTH];
	int loop = 0;
	int value[NTH] = {1,2};
	//printf("\n Going to create threads \n");
	/** Creation of threads*/

/*	for(loop=0; loop<NTH; loop++) {
		pthread_create(&tid[loop], NULL, &sample, &value[loop]);
		printf("\n value of loop = %d\n", loop);
	}
*/
	//gettimeofday(&tv1, NULL);
	pthread_create(&tid[0], NULL, &sample_1, &value[0]);
       	//printf("\n value of loop = %d\n", 0);
	
	pthread_create(&tid[1], NULL, &sample_2, &value[1]);
        //printf("\n value of loop = %d\n", 1);

	/** Synch of threads in order to exit normally*/
	gettimeofday(&tv1, NULL);
	for(loop=0; loop<NTH; loop++) {
		pthread_join(tid[loop], NULL);
	}
	gettimeofday(&tv2, NULL);
	printf("%f\n\r", (double)1000000*(tv2.tv_sec-tv1.tv_sec)+(tv2.tv_usec-tv1.tv_usec));

	int success = 1;
	for(i=0;i<N;i++){
		if(array_input[i]!= array_hardware[i]){
			success = 0;
			printf("read ID %d :%d \n\r",i,array_hardware[i]);
			break;
		}
	}
	if (success == 0){
		printf("Test is unsuccessful!\n\r");

		/*for(i=0; i<N; i++){
                	printf("o/p from p1 is %d\n\r",array_hardware[i]);
		}*/
        }
	
	close(fdw32);
	close(fdr32);

	free(array_input);
	free(array_hardware);
		
	return EXIT_SUCCESS;
//	pthread_exit(NULL);
}