// Travis Rich 10/22/12
// an iteration on top of the following attribution:
//
// hello.arduino.168.blink.c
//
// test blinking LED
//
// Neil Gershenfeld
// 3/14/11
//
// (c) Massachusetts Institute of Technology 2011
// Permission granted for experimental and personal use;
// license for commercial sale available from MIT.
//

#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(1000) // LED delay

#define led_port PORTA
#define led_direction DDRA
#define led_pin (1 << PA7)

// #define button_port PORTA
// #define button_direction DDRA
// #define button_pin (1 << PA6)

#define input_port PORTB
#define input_direction DDRB
#define input_pin (1 << PB2)
#define input_pins PINB

int main(void) {
   //
   // main
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize LED pin
   //
   clear(led_port, led_pin);
   output(led_direction, led_pin);

   clear(input_port, input_pin); // turn on pull-down
   input(input_direction, input_pin);
   //
   // main loop
   //
   // while (1) {
   //    set(led_port, led_pin);
   //    led_delay();
   //    clear(led_port, led_pin);
   //    led_delay();
   //    }
   // }


   while (1) {
      //
      // wait for button down
      //
      if (0 != pin_test(input_pins,input_pin)){
         clear(led_port, led_pin);  
         led_delay();
      }
      set(led_port, led_pin);
      }
   }