multithread matrix multiplication

multithread_matrix_multip.c

#include <stdio.h>
#include <time.h>
#include <stdint.h>
#include <stdlib.h>
#include <pthread.h>

#define MATRIX_SIZE 16
#define RANDOM_LENGHT 10000
#define NTHREAD 4

#define ROW_LENGHT (MATRIX_SIZE/NTHREAD)

static int **matrix_a;
static int **matrix_b;
static int **matrix_mult;

static int **matrix_memory_allocation() {
	int i;
	int j;
	int *vector;
	int **matrix;

	i = 0;
	j = 0;

	/* vektör */
	vector = (int *) malloc(MATRIX_SIZE * MATRIX_SIZE * sizeof(int *));

	matrix = (int **) malloc(MATRIX_SIZE * sizeof(int *));

	for (i = 0; i < MATRIX_SIZE; i++) {
		matrix[i] = &(vector[i * MATRIX_SIZE]);
	}

	srand(time(NULL));
	for (i = 0; i < MATRIX_SIZE; i++) {
		for (j = 0; j < MATRIX_SIZE; j++) {
			matrix[i][j] = random() % RANDOM_LENGHT;
		}
	}

	return matrix;
}

static void print_matrix(int **m)
{
	int i;
	int j;

	for (i = 0; i < MATRIX_SIZE; i++) {
		for (j = 0; j < MATRIX_SIZE; j++) {
			printf("%-15d", m[i][j]);
		}
		printf("\n");
	}
}

static void init(void)
{
	matrix_a = matrix_memory_allocation();
	matrix_b = matrix_memory_allocation();

	matrix_mult = matrix_memory_allocation();

	printf("matrix_a:\n");
	print_matrix(matrix_a);

	printf("matrix_b:\n");
	print_matrix(matrix_b);

}

/*
 * arg -> threads[i]
 *
 * */
static void *process(void *arg)
{
	uintptr_t offset;

	long i, j, k, start, end;
	long sum;

	/*
	 * buradaki tip dönüşümü önemli
	 * programcı bu tip dönüşümünü bilinçli yapmalıdır
	 *
	 * */
	offset = (uintptr_t) arg;

	start = offset * ROW_LENGHT ;
	end = start + ROW_LENGHT;

	for (i = start; i < end; i++) {
		for (j = 0; j < MATRIX_SIZE; j++) {
			sum = 0;
			for (k = 0; k < MATRIX_SIZE; k++) {
				sum += matrix_a[i][k] * matrix_b[k][j];
			}
			matrix_mult[i][j] = sum;
		}
	}

	pthread_exit(NULL);
}

static void report()
{
	printf("matrix_a * matrix_b:\n");
	print_matrix(matrix_mult);
}

static void shutdown(void)
{
	free(matrix_a);
	free(matrix_b);
	free(matrix_mult);
}

int main(int argc, char *argv[])
{
	uintptr_t i;
	pthread_t threads[NTHREAD];

	init();

	for (i = 0; i < NTHREAD; i++) {
		if (pthread_create(&threads[i], NULL, process, (void *) i)) {
			fprintf(stderr, "Cannot create thread!\n");
			exit(EXIT_FAILURE);
		}
	}

	for (i = 0; i < NTHREAD; i++)
		pthread_join(threads[i], NULL);

	report();
	shutdown();

	exit(EXIT_SUCCESS);
}