/******************************************************************************************
* serial_bus.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 combines them bus style
* Note: pyro is a high low not serial
*
* Brian Plancher
* 12/7/16
*
********************************************************************************************/

#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 in
#define serial_in_port PORTA
#define serial_in_direction DDRA
#define serial_in_pins PINA
#define button_1_in (1 << PA0)
#define button_2_in (1 << PA1)
#define perif_in (1 << PA2)

// pyro in
#define pyro_port PORTA
#define pyro_direction DDRA
#define pyro_pins PINA
#define pyro_in (1 << PA3)

// serial port out
#define serial_out_port PORTB
#define serial_out_direction DDRB
#define serial_out_pins PINB
#define serial_out (1 << PB2)

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();
   }

   
int main(void) {
   
   // set clock divider to /1
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);

   // initialize pyro pin
   //input(pyro_direction, pyro_in);
   
   // initialize serial out
   set(serial_out_port, serial_out);
   output(serial_out_direction, serial_out);
   
   // main loop
   char chr = 0;
   while (1) {
      // first see if we have something on the pyro
      if(pin_test(pyro_pins,pyro_in)){
         chr = 'A';
         put_char(&serial_out_port, serial_out, chr); // indicates an alarm sensor triggered
      }
      // else do non-blocking reads on the serial inputs to get the right char and send it
      else if(!pin_test(serial_in_pins,button_1_in)){
         get_char(&serial_in_pins, button_1_in, &chr);
         put_char(&serial_out_port, serial_out, chr);
      }
      else if(!pin_test(serial_in_pins,button_2_in)){
         get_char(&serial_in_pins, button_2_in, &chr);
         put_char(&serial_out_port, serial_out, chr);
      }
      /*
      else if(!pin_test(serial_in_pins,perif_in)){
         get_char(&serial_in_pins, perif_in, &chr);
         put_char(&serial_out_port, serial_out, 'C');
      }
      */
   }
}