/*
  Filename: 8x8hello.c

  The file to include the font must be in the working directory,
  it's filename is: 8x8font.dat

  Turns on and off LEDs at to display letters in an 8x8 matrix.

  Pins 0-7 are the row pins, on if HIGH.
  Pins 8-15 are the column pins, on if LOW.

The array for each letter looks like this:

int f_A[8][8] = { {0,0,0,0,0,0,0,0},   // Letter "A"
		  {0,0,1,0,0,0,0,0},
		  {0,1,0,1,0,0,0,0},
		  {1,0,0,0,1,0,0,0},
		  {1,1,1,1,1,0,0,0},
		  {1,0,0,0,1,0,0,0},
		  {1,0,0,0,1,0,0,0},
		  {1,0,0,0,1,0,0,0} };
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <wiringPi.h>

#include "./8x8font.dat"

int rowPin[8] = {0,1,2,3,4,5,6,7};
int columnPin[8] = {8,9,10,11,12,13,14,15}; 

int LED[8][8]; //8 rows, 8 columns.  Used for passing data between threads.

void setup(void)
{
  int i;

  if (geteuid() != 0)
  {
    fprintf (stderr, "You need to be root to run this program. (sudo?)\n") ;
    exit(0) ;
  }

  if (wiringPiSetup() == -1)
  {
    printf("wiringPiSetup error\n");
    exit(1) ;
  }

  for(i = 0; i < 16; i++)
  {                            
    pinMode(i,OUTPUT);  // Set pins 0 - 15 for output.
  }                                  
}

/*
 This thread reads the LED array and performs the multiplex.  
 It turns on the pins for one LED at a time. 

 Row 1 LED 1 - 2 - 3 ...
 Row 2 LED 1 - 2 - 3 ...

 The code here runs concurrently with the main program in an infinite loop.
*/
PI_THREAD (display)
{
  int i,j;

  while(1)
  {
    for(i = 0; i < 8; i++)                     // Row, HIGH is on. 
    {
      if(i==0) digitalWrite(rowPin[7],0);      // Turn off previous row.
      else digitalWrite(rowPin[i-1],0);
      digitalWrite(columnPin[7],1);            // turn off column 7 pin.
   
      digitalWrite(rowPin[i],1);               // Turn on current row.

      for(j = 0; j < 8; j++)                   // Column, LOW is on.
      {
        if(j==0) digitalWrite(columnPin[7],1); // Turn off previous column.
        else digitalWrite(columnPin[j-1],1);
        
        if (LED[i][j]==1)
        {
          digitalWrite(columnPin[j],0);        // Turn on current column.
        }
      }
    }
  }
}

/*
 Function to display one letter.

 The letter array is copied to the LED array.
*/
void dspLetter(int letter[8][8])
{
int i,j;
  for(i=0;i<8;i++)
  {
    for(j=0;j<8;j++)
    {
      LED[i][j] = letter[i][j]; //Move letter to LED for display
    }
  }
}

/*
 The loop function writes passes the letters to the dspLetter function.
*/
void loop(void)
{
  dspLetter(f_H);
  delay(500);

  dspLetter(f_E);
  delay(500);

  dspLetter(f_L);
  delay(500);

  dspLetter(f_SP);
  delay(200);

  dspLetter(f_L);
  delay(500);

  dspLetter(f_O);
  delay(500);

  dspLetter(f_SP);
  delay(1000);


  dspLetter(f_W);
  delay(500);

  dspLetter(f_O);
  delay(500);

  dspLetter(f_R);
  delay(500);

  dspLetter(f_L);
  delay(500);

  dspLetter(f_D);
  delay(500);

  dspLetter(f_SP);
  delay(1000);

  dspLetter(f_A);
  delay(500);

  dspLetter(f_B);
  delay(500);

  dspLetter(f_C);
  delay(500);

  dspLetter(f_D);
  delay(500);

  dspLetter(f_E);
  delay(500);

  dspLetter(f_F);
  delay(500);

  dspLetter(f_G);
  delay(500);

  dspLetter(f_H);

  delay(500);
  dspLetter(f_I);
  delay(500);

  dspLetter(f_J);
  delay(500);

  dspLetter(f_K);
  delay(500);

  dspLetter(f_L);
  delay(500);

  dspLetter(f_M);
  delay(500);

  dspLetter(f_N);
  delay(500);

  dspLetter(f_O);
  delay(500);

  dspLetter(f_P);
  delay(500);

  dspLetter(f_Q);
  delay(500);

  dspLetter(f_R);
  delay(500);

  dspLetter(f_S);
  delay(500);

  dspLetter(f_T);
  delay(500);

  dspLetter(f_U);
  delay(500);

  dspLetter(f_V);
  delay(500);

  dspLetter(f_W);
  delay(500);

  dspLetter(f_X);
  delay(500);

  dspLetter(f_Y);
  delay(500);

  dspLetter(f_Z);
  delay(500);

  dspLetter(f_SP);
  delay(1000);
}


int main(void)
{
  int x = piThreadCreate (display) ;         // Start second thread.
  if (x != 0) printf ("It didn't start.\n");

  setup();

  while(1)
  {
    loop();
  }

  return(0);
}