/*
  MNIST.c
*/

#include <fcntl.h> //  open
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h> // read
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h> // exit
#include "mnist.h"
#include "irl_utility.h"

double **mnist_read_images(){
  
  unsigned char **digit;
  double **retval;
  int n = MNIST_NUM_IMAGES;

  digit = alloc_2d_uchar(n, MNIST_NUM_PIXELS);
  retval = alloc_2d_dbl(n, MNIST_NUM_PIXELS);
  
  int i, j, fd;
  static int num[10];
  
  if ((fd=open(MNIST_IMAGE_FILE,O_RDONLY))==-1){
    printf("couldn't open image file");
    exit(0);
  }
  
  /* skip headers */
  read(fd,num, 4*sizeof(int) );
  for (i=0; i<MNIST_NUM_IMAGES; i++) {
    read(fd,digit[i], MNIST_NUM_PIXELS*sizeof(unsigned char) );
  }
  close(fd);

  for (i=0; i<MNIST_NUM_IMAGES; i++) {
    for (j=0; j<MNIST_NUM_PIXELS; j++) {
      retval[i][j] = digit[i][j];
    }
  }
  
  for (i=0; i<n; i++) {
    free((char *) digit[i] );
  }
  free((char *) digit);
  
  return retval;
 }



int *mnist_read_labels(){

  int i;
  int n = MNIST_NUM_IMAGES;
  unsigned char *label;
  int *retval;
  label = alloc_1d_uchar(n);
  retval = alloc_1d_int(n);
  
  int fd;
  static int num[10];
  
  if ((fd=open(MNIST_LABEL_FILE,O_RDONLY))==-1){
    printf("couldn't open image file");
    exit(0);
  }
  
  /* skip headers */
  read(fd,num, 2*sizeof(int) );
  read(fd, label, MNIST_NUM_IMAGES*sizeof(unsigned char) );
  close(fd);
  
  for (i=0; i<MNIST_NUM_IMAGES; i++) {
      retval[i] = label[i];
  }
  
  free((char *) label);
  return retval;
  
 }