/* seqmm.c sequential square matrix multiplication */
#include <stdlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>
#include "matrix.h"

int parse_args(int argc,  char *argv[ ], int *size){
  if ( (argc != 5) || ((*size = atoi (argv[4])) <= 0) ) {
    fprintf (stderr, "Usage: %s MatrixA MatrixB MatrixC Size\n", argv[0]);
    return(-1); };
  return(0); 
}

int main(int argc,  char *argv[ ])
{
   int dim; /* matrix dimensions */
 
   if(parse_args(argc,argv,&dim) < 0) exit(0);

   {
     int   fd[3];                       /* A B and C's fd's        */
     int A[dim+1][dim+1], B[dim+1][dim+1], C[dim+1][dim+1];  /* A B and C               */
     int i, j, k;
   
     /* open files */
     if(((fd[0] = open(argv[1], O_RDONLY)) == -1) ||
        ((fd[1] = open(argv[2], O_RDONLY)) == -1) ||
        ((fd[2] = open(argv[3], O_WRONLY | O_CREAT, 0666)) == -1)){
       perror("Opening files failed");
       exit(EXIT_FAILURE);}
     /* read A */
     for( i = 1; i < dim+1; i++ )
       if(get_row(fd[0], dim, i, &A[i][1]) == -1)
         fprintf(stderr,"Initialization of A failed at row %d\n", i);
     /* read B */
     for( i = 1; i < dim+1; i++ )
       if(get_row(fd[1], dim, i, &B[i][1]) == -1)
         fprintf(stderr,"Initialization of B failed at row %d\n", i);

     for( i = 1; i < dim+1; i++ )
       for( j = 1; j < dim+1; j++ ) {
         C[i][j] = 0;
         for( k = 1; k < dim+1; k++ )
           C[i][j] += A[i][k] * B[k][j];
       }

     /* write C */
     for( i = 1; i < dim+1; i++ )
       if(set_row(fd[2], dim, i, &C[i][1]) == -1)
         fprintf(stderr,"Write of C failed at row %d\n", i);

     close( fd[0] ); close( fd[1] ); close( fd[2] );
  }
  return 0; 
}     /* end of main program here */