// Compile with `gcc -Wall -o read_typewriter_signals read_typewriter_signals.c -lwiringPi`

#include <wiringPi.h>
#include <stdio.h>
 
int main(void) {
  wiringPiSetup();
  setbuf(stdout, NULL);

  int scanPins[] = {5, 22, 10, 11, 26, 27, 28, 29};
  int signalPins[] = {13, 12, 3, 2, 0, 7, 24, 23};
  
  int i = 0;
  int j = 0;
  for (i=0; i<8; i++) {
    pinMode(scanPins[i], INPUT);
    pinMode(signalPins[i], INPUT);
    pullUpDnControl(scanPins[i], PUD_UP);
    pullUpDnControl(signalPins[i], PUD_UP);
  }
  
  int keyDown[8][8] = {
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0}
  };

  int lastI;
  int lastJ;
  int sameKeyCount = 0;
  for (;;) {
    for (i=0; i<8; i++) {
      for (j=0; j<8; j++) {
        if (digitalRead(scanPins[i]) == LOW && digitalRead(signalPins[j]) == LOW) {
          (i == lastI && j == lastJ) ? sameKeyCount++ : sameKeyCount = 0;

          if (sameKeyCount > 50 && keyDown[i][j] <= 0) {
            printf("%d,%d\n", i, j);
            keyDown[i][j] = 50;
          }
          lastI = i;
          lastJ = j;
        }
        
        if (digitalRead(scanPins[i]) == LOW && digitalRead(signalPins[j]) == HIGH) {
          keyDown[i][j] = (keyDown[i][j] - 1);
        }
      }
    }
  }
}