//#include <w77c32.h>
#include <at89x55.h>
#include "../shared.h"

/* possible states of the badge */
#define RECEIVING_REQUEST 1
#define SENDING_REPLY 2

/* reload value for 16-bit 10 ms counter assuming 22MHz clock */
#define RELOAD_HI 0xB8
#define RELOAD_LO 0x63

#define IN_BUFFER_SIZE 8
#define OUT_BUFFER_SIZE 8

/* buffers */
unsigned char in_buffer [IN_BUFFER_SIZE];
unsigned char out_buffer [OUT_BUFFER_SIZE];

/* total # of bytes received into in_buffer */
unsigned char bytes_received = 0;
/* # of bytes sent from out_buffer */
unsigned char bytes_sent = 0;
/* total # of bytes to send from out_buffer */
unsigned char bytes_to_send = 0;

/* 50 ms time out flag */
unsigned char timed_out = 0;

/* badge ID */
unsigned char badgeID = 'l';

/* create reply packet in out_buffer according to in_buffer */
void format_reply(char* in_buffer, char* out_buffer);

/* set SFR values on startup */
void init();

/* send address byte of packet to test if RF board is busy */
void send_address_byte();


void main() 
{
	/* state of badge */
	unsigned char state = RECEIVING_REQUEST;
	//P1 = 0x00;

	init();

	/* loop forever to serve requests */
    for(;;) {
		switch(state) {
		case RECEIVING_REQUEST:
			if(bytes_received >= HEADER_LENGTH + REQUEST_LENGTH) {				
				state = SENDING_REPLY;	
			}
			break;
		case SENDING_REPLY:
			/* for demo: read ID from port 1 */
			badgeID = P1;

			bytes_received = 0;
			format_reply(in_buffer, out_buffer);
			
			//send address byte of packet to test if RF board is busy
			send_address_byte();
			//wait till RF board is NOT busy
			while(1) {
				if (bytes_received > 0) {
					if(in_buffer[0] == out_buffer[0]) {
 				    	//address byte echoed; send the rest of packet
						TR0 = 0;
						bytes_to_send = HEADER_LENGTH + RESPONSE_LENGTH;
						//assert(bytes_sent == 1);
						TI = 1;
						break;
					}
					bytes_received = 0;
				} else if (timed_out) {
					//test again
					send_address_byte();
				}				
			}

			//wait till whole packet's been sent
			while(bytes_sent < bytes_to_send) ;

			bytes_received = 0;
			state = RECEIVING_REQUEST;
			break;
		default:
			bytes_received = 0;
			state = RECEIVING_REQUEST;
		}

   	}    
}/* end of main */



/* create the reply packet in out_buffer */
void format_reply(char* in_buffer, char* out_buffer) {
	//swap the upper 4 bits with the lower 4
	char temp = in_buffer[0] << 4;
	out_buffer[0] = temp | in_buffer[0] >> 4;
	
	out_buffer[1] = 8; //telemetry
	out_buffer[2] = RESPONSE_LENGTH;
	out_buffer[3] = 2;
	out_buffer[4] = RESPONSE_CODE;
	out_buffer[5] = badgeID;
	out_buffer[6] = 3;
}


//send address byte of packet to test if RF board is busy
void send_address_byte() {
	timed_out = 0;
	bytes_sent = 0;
	bytes_to_send = 1;
	TH0 = RELOAD_HI;
	TL0 = RELOAD_LO;
	TR0 = 1; //set time-out
	TI = 1;
}


void Timer0_ISR () interrupt 1 {
	static unsigned char count = 0;
	if(++count == 5) {
		TR0 = 0;
		count = 0;
		timed_out = 1;
	}
	TH0 = RELOAD_HI;
	TL0 = RELOAD_LO;
} /* end of Timer0_ISR() */



void Serial_ISR() interrupt 4 {
	if(RI==1) {
		RI = 0;
		if(bytes_received < IN_BUFFER_SIZE)
			in_buffer[bytes_received++] = SBUF;
	} else {	
		TI = 0;
		if(bytes_sent < bytes_to_send)
			SBUF = out_buffer[bytes_sent++];
	}
}/* end of Serial_ISR() */


void init() {
	/* interrupt settings */
	EA = 1;
	ET0 = 1;
	ET1 = 0;
	ES = 1;

	/* set serial */
	SM0 = 0;
	SM1 = 1;
	REN = 1;

	/* setup timer0 as a 50 ms counter, timer1 as 19.2 kbps baud rate generator, assuming a 22MHz clock */
	TMOD = 0x21;
	PCON = PCON | 0x80;
	TH0 = RELOAD_HI;
	TL0 = RELOAD_LO;
	TH1 = 250;
	TR1 = 1;
}/* end of init() */