#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <wait.h>
#include <wiringPi.h>

#define IN1 26
#define IN2 27
#define IN3 28
#define IN4 29

#define OU1 22
#define OU2 23
#define OU3 24
#define OU4 25


void Delay();
int last;

int main (void)
{
  int k;

  if (wiringPiSetup () == -1)
  exit (1) ;

    pinMode(IN1, OUTPUT);
    digitalWrite (IN1, 0);
    pinMode(IN2, OUTPUT);
    digitalWrite (IN2, 0);
    pinMode(IN3, OUTPUT);
    digitalWrite (IN3, 0);
    pinMode(IN4, OUTPUT);
    digitalWrite (IN4, 0);

    pinMode(OU1, INPUT);
    pullUpDnControl (OU1, PUD_DOWN) ;
    pinMode(OU2, INPUT);
    pullUpDnControl (OU2, PUD_DOWN) ;
    pinMode(OU3, INPUT);
    pullUpDnControl (OU3, PUD_DOWN) ;
    pinMode(OU4, INPUT);
    pullUpDnControl (OU4, PUD_DOWN) ;

  for(;;)
 {
   if (k=read_key() ) printf("%c", k);
 }
}

int read_key()
{
  int kod=0;
  digitalWrite (IN1, 1);
  Delay(5);
  if (digitalRead(OU1)==1) {kod=0x44;}
  if (digitalRead(OU2)==1) {kod=0x23;}
  if (digitalRead(OU3)==1) {kod=0x30;}
  if (digitalRead(OU4)==1) {kod=0x2A;}
  digitalWrite (IN1, 0);

  digitalWrite (IN2, 1);
  Delay(5);
  if (digitalRead(OU1)==1) {kod=0x43;}
  if (digitalRead(OU2)==1) {kod=0x39;}
  if (digitalRead(OU3)==1) {kod=0x38;}
  if (digitalRead(OU4)==1) {kod=0x37;}
  digitalWrite (IN2, 0);

  digitalWrite (IN3, 1);
  Delay(5);
  if (digitalRead(OU1)==1) {kod=0x42;}
  if (digitalRead(OU2)==1) {kod=0x36;}
  if (digitalRead(OU3)==1) {kod=0x35;}
  if (digitalRead(OU4)==1) {kod=0x34;}
  digitalWrite (IN3, 0);

  digitalWrite (IN4, 1);
  Delay(5);
  if (digitalRead(OU1)==1) {kod=0x41;}
  if (digitalRead(OU2)==1) {kod=0x33;}
  if (digitalRead(OU3)==1) {kod=0x32;}
  if (digitalRead(OU4)==1) {kod=0x31;}
  digitalWrite (IN4, 0);
 
 if (kod != last)
   {
    last = kod;
    return kod ;
   }
  else
   {
    return 0;
   }
}
void Delay(int microsec)
{
 struct timespec tim;
 tim.tv_sec = 0;
 tim.tv_nsec = microsec * 1000;
     while(nanosleep(&tim,&tim)==-1)
          continue;
}