/******************************************************************************************
* master.c
*
* based on hello.ftdi.c by Neil Gershenfeld
*      and button44 by Rob Hart
* set lfuse to 0x5E for 20 MHz xtal
*
* Recieves data over serial and displays LEDs
*
* Brian Plancher
* 11/21/16
*
********************************************************************************************/

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

// helper defs
#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 bit_delay_time 8.5 // bit delay for 115200 with overhead
#define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
#define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
#define char_delay() _delay_ms(10) // char delay
#define long_delay() _delay_ms(1000) // long delay

// serial port
#define serial_port PORTA
#define serial_direction DDRA
#define serial_pins PINA
#define serial_pin_in (1 << PA0)
#define serial_pin_out (1 << PA1)

// input devices
#define input_pins PINA			//  PINA is the register that is read to detect input high or low.
#define LED_port PORTA		//  port A will be used for the LED
#define LED_direction DDRA
#define LED1_pin (1 << PA2)
#define LED2_pin (1 << PA3)
#define LED3_pin (1 << PA7)

// for serial comms
#define max_buffer 25

void get_char(volatile unsigned char *pins, unsigned char pin, char *rxbyte) {
   //
   // read character into rxbyte on pins pin
   //    assumes line driver (inverts bits)
   //
   *rxbyte = 0;
   /* while (pin_test(*pins,pin))
      //
      // wait for start bit
      //
      ; */
   //
   // delay to middle of first data bit
   //
   half_bit_delay();
   bit_delay();
   //
   // unrolled loop to read data bits
   //
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 0);
   else
      *rxbyte |= (0 << 0);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 1);
   else
      *rxbyte |= (0 << 1);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 2);
   else
      *rxbyte |= (0 << 2);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 3);
   else
      *rxbyte |= (0 << 3);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 4);
   else
      *rxbyte |= (0 << 4);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 5);
   else
      *rxbyte |= (0 << 5);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 6);
   else
      *rxbyte |= (0 << 6);
   bit_delay();
   if pin_test(*pins,pin)
      *rxbyte |= (1 << 7);
   else
      *rxbyte |= (0 << 7);
   //
   // wait for stop bit
   //
   bit_delay();
   half_bit_delay();
   }

void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
   //
   // send character in txchar on port pin
   //    assumes line driver (inverts bits)
   //
   // start bit
   //
   clear(*port,pin);
   bit_delay();
   //
   // unrolled loop to write data bits
   //
   if bit_test(txchar,0)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,1)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,2)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,3)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,4)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,5)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,6)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   if bit_test(txchar,7)
      set(*port,pin);
   else
      clear(*port,pin);
   bit_delay();
   //
   // stop bit
   //
   set(*port,pin);
   bit_delay();
   //
   // char delay
   //
   bit_delay();
   }

void put_string(volatile unsigned char *port, unsigned char pin, char *str) {
   //
   // print a null-terminated string
   //
   static int index;
   index = 0;
   do {
      put_char(port, pin, str[index]);
      ++index;
      } while (str[index] != 0);
   }
   
int main(void) {
   
   // set clock divider to /1
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);

   // initialize pins
   //set(serial_port, serial_pin_out);
   //output(serial_direction, serial_pin_out);
   output(LED_direction, LED1_pin|LED2_pin|LED3_pin); // sed LEDs for output
   
   // main loop
   char chr = 0;
   while (1) {
      if(!pin_test(serial_pins,serial_pin_in)){
         get_char(&serial_pins, serial_pin_in, &chr);
         if (chr == 'B'){
            set(LED_port,LED1_pin);
         }
         else if(chr == 'A'){
            set(LED_port,LED2_pin);
         }
         clear(LED_port,LED3_pin);
         long_delay();
      }
      else if(!pin_test(serial_pins,serial_pin_out)){
         get_char(&serial_pins, serial_pin_out, &chr);
         if (chr == 'B'){
           set(LED_port,LED1_pin);
         }
         else if(chr == 'A'){
            set(LED_port,LED2_pin);
         }
         clear(LED_port,LED3_pin);
         long_delay();
      }
      else{
         clear(LED_port,LED1_pin);
         clear(LED_port,LED2_pin);
         set(LED_port,LED3_pin);
      }
   }
}