// C Program to multiply two matrix using pthreads without
// use of global variables
#include<stdio.h>
#include<pthread.h>
#include<unistd.h>
#include<stdlib.h>
#define MAX 3
 
 
//Each thread computes single element in the resultant matrix
void *mult(void* arg)
{
    int *data = (int *)arg;
    int k = 0, i = 0;
     
    int x = data[0];
    for (i = 1; i <= x; i++)
           k += data[i]*data[i+x];
     
    int *p = (int*)malloc(sizeof(int));
         *p = k;
     
//Used to terminate a thread and the return value is passed as a pointer
    pthread_exit(p);
}
 
//Driver code
int main()
{
 
    int matA[MAX][MAX];
    int matB[MAX][MAX];
     
     
    int r1=MAX,c1=MAX,r2=MAX,c2=MAX,i,j,k;
 
 
    // Generating random values in matA
    for (i = 0; i < r1; i++)
            for (j = 0; j < c1; j++)
                   matA[i][j] = rand() % 10;
           
        // Generating random values in matB
    for (i = 0; i < r1; i++)
            for (j = 0; j < c1; j++)
                   matB[i][j] = rand() % 10;
    // Displaying matA 
    printf("Displaying matA\n");       
    for (i = 0; i < r1; i++){
        for(j = 0; j < c1; j++)
            printf("%d ",matA[i][j]);
        printf("\n");
    }
     
     printf("\n");
     printf("\n");
             
    // Displaying matB 
    printf("Displaying matB\n");               
    for (i = 0; i < r2; i++){
        for(j = 0; j < c2; j++)
            printf("%d ",matB[i][j]);
        printf("\n");   
    }
    
    printf("\n");
     printf("\n"); 
     
    int max = r1*c2;
     
     
    //declaring array of threads of size r1*c2       
    pthread_t *threads;
    threads = (pthread_t*)malloc(max*sizeof(pthread_t));
     
    int count = 0;
    int* data = NULL;
    for (i = 0; i < r1; i++)
        for (j = 0; j < c2; j++)
               {
                
               //storing row and column elements in data
            data = (int *)malloc((20)*sizeof(int));
            data[0] = c1;
     
            for (k = 0; k < c1; k++)
                data[k+1] = matA[i][k];
     
            for (k = 0; k < r2; k++)
                data[k+c1+1] = matB[k][j];
              
             //creating threads
                pthread_create(&threads[count++], NULL,
                               mult, (void*)(data));
                 
                    }
     
    printf("RESULTANT MATRIX IS :- \n");
    for (i = 0; i < max; i++)
    {
      void *k;
      //Joining all threads and collecting return value
      pthread_join(threads[i], &k);
            
           
          int *p = (int *)k;
      printf("%d ",*p);
      if ((i + 1) % c2 == 0)
          printf("\n");
    }
 
     
 
  return 0;
}