#include <avr/io.h>
#include <util/delay.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define input(directions,pin) (directions &= (~pin)) // set port direction for input 
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set

#define led_delay() _delay_ms(1) // LED delay
#define blink_delay() _delay_ms(100) // blink delay

#define led_port PORTA
#define led_direction DDRA

#define A (1 << PA1) // row 1
#define B (1 << PA2) // row 2
#define C (1 << PA3) // row 3
#define D (1 << PA4) // row 4
#define E (1 << PA5) // row 5

void flash(uint8_t from, uint8_t to, uint8_t delay) {
   //
   // source from, sink to, flash
   //
   static uint8_t i;
   set(led_port,from);
   clear(led_port,to);
   output(led_direction,from);
   output(led_direction,to);
   for (i = 0; i < delay; ++i)
       led_delay();
   input(led_direction,from);
   input(led_direction,to);
   }

void led_cycle(uint8_t number, uint8_t delay) {
   //
   // cycle through LEDs
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
      flash(B,A,delay);
      flash(C,A,delay);
      flash(D,A,delay);
      flash(E,A,delay);
      flash(A,B,delay);
      flash(C,B,delay);
      flash(D,B,delay);
      flash(E,B,delay);
      flash(A,C,delay);
      flash(B,C,delay);
      flash(D,C,delay);
      flash(E,C,delay);
      flash(A,D,delay);
      flash(B,D,delay);
      flash(C,D,delay);
      flash(E,D,delay);
      flash(A,E,delay);
      flash(B,E,delay);
      flash(C,E,delay);
      flash(D,E,delay);
      }
   }


void display_H(uint8_t number, uint8_t delay) {
   //
   // letter H
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
     // left leg
      flash(B,A,delay);
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(A,E,delay);
      // middle line
      flash(B,C,delay);
      flash(D,C,delay);
      //right leg
      flash(D,E,delay);
      flash(E,D,delay);
      flash(E,C,delay);
      flash(E,B,delay);
      flash(E,A,delay);
      }
   }

void display_E(uint8_t number, uint8_t delay) {
   //
   // letter E
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
     // left leg
      flash(B,A,delay);
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(A,E,delay);
      // middle line
      flash(B,C,delay);
      flash(D,C,delay);
      //top leg
      flash(B,A,delay);
      flash(C,A,delay);
      flash(D,A,delay);
      flash(E,A,delay);
      // bottom leg
      flash(A,E,delay);
      flash(B,E,delay);
      flash(C,E,delay);
      flash(D,E,delay);
      }
   }
   
   void display_L(uint8_t number, uint8_t delay) {
   //
   // letter L
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
     // left leg
      flash(B,A,delay);
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(A,E,delay);
      // bottom leg
      flash(A,E,delay);
      flash(B,E,delay);
      flash(C,E,delay);
      flash(D,E,delay);
      }
   }
   
   void display_O(uint8_t number, uint8_t delay) {
   //
   // letter O
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
     // left leg
      flash(B,A,delay);
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(A,E,delay);
      //top leg
      flash(B,A,delay);
      flash(C,A,delay);
      flash(D,A,delay);
      flash(E,A,delay);
      // bottom leg
      flash(A,E,delay);
      flash(B,E,delay);
      flash(C,E,delay);
      flash(D,E,delay);
       //right leg
      flash(D,E,delay);
      flash(E,D,delay);
      flash(E,C,delay);
      flash(E,B,delay);
      flash(E,A,delay);
      }
   }
   

 
  

   
int main(void) {
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // main loop
   //
   while (1) {
     // cycle thorugh 1 time with 100 ms between
      //led_cycle(1,100);
     // led_cycle(3,20);
     // cycle through 100 times with 1 ms between
      display_H(10,1);
      blink_delay();
      display_E(10,1);
      blink_delay();
      display_L(15,1);
      blink_delay();
      display_L(15,1);
      blink_delay();
      display_O(10,1);
      blink_delay();
    
      }
   }