/* File: sorting.c
   Support routines for sorting binary files
   which contain arrays of integers.
*/

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "sorting.h"


/* Get file size of open stream 
   returns -1 as error  
*/
int fsize(FILE *ifile) {
   int r, size ;
   struct stat buf ;
   
   if (ifile == NULL) return -1 ;

   r = fstat(ifile->_file, &buf) ;
   if (r != 0) return -1 ;
   return buf.st_size ;
}


/* Read an array of integers stored
   in binary file 
   Returns number of items read or
   -1 for error. If no items read,
   *A is not changed.
*/

index readarray(char *filename, data **A_ptr) {
   FILE *ifile ;
   index n ;
   int r, size ;

   ifile = fopen(filename, "rb")  ;
   if (ifile == NULL) return -1 ;

   size = fsize(ifile) ;
   if (size < 0) return -1 ;

   n = size/sizeof(data) ;
   if (n == 0) return 0 ;

   *A_ptr = (data *) malloc(n*sizeof(data)) ;
   r = fread(*A_ptr, sizeof(data), n, ifile) ;
   fclose(ifile) ;

   if (n != r) {
      fprintf(stderr, "Bad file format\n") ;
      exit(-1) ;
   }
   return n ;
}


void printarray(data A[], index n) {
   index i ;

   for (i = 0 ; i < n ; i++) {
      printf("%12d ", A[i]) ;
      if (i % 5 == 4) printf("\n") ;
   }
}

int checkarray(data A[], index n) {
   index i ;

   for (i = 0 ; i < n-1 ; i++) {
      if (A[i] > A[i+1]) return 0 ;
   }
   return 1 ;
}