/*
  Filename: 8x8life.c

  Turns on and off LEDs at to display Conway's game of life in an 8x8 matrix.

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

*/

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


int start[10][10] = { {0,0,0,0,0,0,0,0,0,0},   // The starting point
	   	      {0,0,0,0,0,0,0,0,0,0},
		      {0,0,0,1,0,0,0,0,0,0},
		      {0,0,1,0,1,0,0,0,0,0},
		      {0,1,0,0,0,1,0,0,0,0},
		      {0,1,1,1,1,1,0,0,0,0},
		      {0,1,0,0,0,1,0,0,0,0},
	  	      {0,1,0,0,0,1,0,0,0,0},
	  	      {0,1,0,0,0,1,0,0,0,0},
		      {0,0,0,0,0,0,0,0,0,0} };


/*
int start[10][10] = { {0,0,0,0,0,0,0,0,0,0},   // The starting point
	   	      {0,0,0,0,0,0,0,0,0,0},
		      {0,0,1,1,1,0,1,0,0,0},
		      {0,0,1,0,0,0,0,0,0,0},
		      {0,0,0,0,0,1,1,0,0,0},
		      {0,0,0,1,1,0,1,0,0,0},
		      {0,0,1,0,1,0,1,0,0,0},
	  	      {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 count[10][10]; //Count of adjacent live cells.

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.

/*
 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.
        }
      }
    }
  }
}



void setup(void)
{
  int i,j;

  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.
  } 

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

  for(i=0;i<8;i++)  // Display initial sequence.
  {
    for(j=0;j<8;j++)
    {
      LED[i][j] = start[i+1][j+1]; //Move matrix to LED for display
    }
  }


  delay(2000);
                                 
}



/*
 The loop function.
*/
/*******************************************************/

void loop(void)
{
  int i,j;

  for(i=0;i<10;i++)     // Zero counts from previous iteration.
  {
    for(j=0;j<10;j++)
    {
      count[i][j]=0;
    }
  }

/*******************************************************/

  for(i=1;i<9;i++)     // Count adjacent live cells.
  {
    for(j=1;j<9;j++)
    {
      if(start[i-1][j-1]==1) count[i][j]++;
      if(start[i-1][j]==1) count[i][j]++;
      if(start[i-1][j+1]==1) count[i][j]++;

      if(start[i][j-1]==1) count[i][j]++;
      if(start[i][j+1]==1) count[i][j]++;

      if(start[i+1][j-1]==1) count[i][j]++;
      if(start[i+1][j]==1) count[i][j]++;
      if(start[i+1][j+1]==1) count[i][j]++;
    }
  }

/*******************************************************/

  for(i=1;i<9;i++)     // Switch on/off cells.
  {
    for(j=1;j<9;j++)
    {
      if (count[i][j]<2) start[i][j]=0;
      if (count[i][j]>3) start[i][j]=0;
      if (count[i][j]==3) start[i][j]=1;
    }
  }

/*******************************************************/

  for(i=0;i<8;i++)
  {
    for(j=0;j<8;j++)
    {
      LED[i][j] = start[i+1][j+1]; //Move matrix to LED for display
    }
  }


  delay(500);
}

/*******************************************************/

int main(void)
{
  int i,j;
  int previous[10][10];
  int endflag = 1;

  setup();

  while(endflag > 0)
  {
     for(i=0;i<10;i++)     // Save current matrix.
    {
      for(j=0;j<10;j++)
      {
        previous[i][j] = start[i][j];
      }
    }

    loop(); // Perfoem one iteration.
    
    endflag = 0;

    for(i=0;i<10;i++)   // Compare previous matrix to current. 
    {
      for(j=0;j<10;j++)
      {
        if(previous[i][j] != start[i][j])
        {
          endflag++;
          i = 10;
          j = 10;
        }
      }
    }
  }
  delay(2000);

  return(0);
}