// MIDI Filter

/*
VPP			|	1		18	|	3.3V
midi ch 0	|	2		17	|	GND
midi ch 1	|	3		16	|	LED Out
midi ch 2	|	4		15	|	-> MIDI Out
midi ch 3	|	5		14	|	VCAP
XTAL		|	6		13	|	GND
XTAL		|	7		12	|	Send Next Channel Also	
ICSP		|	8		11	|	Spare Input
ICSP		|	9		10	|	<- MIDI in	
*/



#include <p24HJ12GP201.h>
#include <p24Hxxxx.h>

// FBS
#pragma config BWRP = WRPROTECT_OFF     // Boot Segment Write Protect (Boot Segment may be written)
#pragma config BSS = NO_FLASH           // Boot Segment Program Flash Code Protection (No Boot program Flash segment)

// FGS
#pragma config GWRP = OFF               // General Code Segment Write Protect (User program memory is not write-protected)
#pragma config GSS = OFF                // General Segment Code Protection (User program memory is not code-protected)

// FOSCSEL
#pragma config FNOSC = PRI              // Oscillator Mode (Primary Oscillator (XT, HS, EC))
#pragma config IESO = OFF               // Internal External Switch Over Mode (Start-up device with user-selected oscillator source)

// FOSC
#pragma config POSCMD = HS              // Primary Oscillator Source (HS Oscillator Mode)
#pragma config OSCIOFNC = ON            // OSC2 Pin Function (OSC2 pin has digital I/O function)
#pragma config IOL1WAY = OFF            // Peripheral Pin Select Configuration (Allow Multiple Re-configurations)
#pragma config FCKSM = CSDCMD           // Clock Switching and Monitor (Both Clock Switching and Fail-Safe Clock Monitor are disabled)

// FWDT
#pragma config WDTPOST = PS32768        // Watchdog Timer Postscaler (1:32,768)
#pragma config WDTPRE = PR128           // WDT Prescaler (1:128)
#pragma config WINDIS = OFF             // Watchdog Timer Window (Watchdog Timer in Non-Window mode)
#pragma config FWDTEN = OFF             // Watchdog Timer Enable (Watchdog timer enabled/disabled by user software)

// FPOR
#pragma config FPWRT = PWR8             // POR Timer Value (8ms)
#pragma config ALTI2C = OFF             // Alternate I2C  pins (I2C mapped to SDA1/SCL1 pins)

// FICD
#pragma config ICS = PGD2               // Comm Channel Select (Communicate on PGC2/EMUC2 and PGD2/EMUD2)
#pragma config JTAGEN = OFF             // JTAG Port Enable (JTAG is Disabled)

//Midi Status Messages
#define 	SYSTEM_EXCLUSIVE	0xF0	
#define		MIDI_TIME_CODE		0xF1	
#define		SONG_POS			0xF2	
#define		SONG_SELECT			0xF3	
#define		TUNE_REQUEST		0xF6


unsigned int midiChannelNumber;
unsigned int sendNextChannelAlso = 0;

unsigned int sendingThisMessage = 0;

unsigned char garbage;


#define BUFFER_SIZE	256

volatile unsigned char midiBuffer[BUFFER_SIZE];
volatile unsigned int 	putCounter = 0;
volatile unsigned int 	getCounter = 0;

volatile unsigned int 	midiByteToProcess;





void __attribute__ ((interrupt, no_auto_psv)) _U1RXInterrupt(void){

	//LATBbits.LATB15 ^= 1;

	if(U1STAbits.FERR){
	
		if(U1STAbits.URXDA)	{
			garbage = U1RXREG;
		}
		
		IFS0bits.U1RXIF =0;

	}
	else if(U1STAbits.OERR){

		garbage = U1RXREG;
		
		U1STA = 0x480;
		U1STA = 0x490;
		
		if(IFS0bits.U1RXIF)	garbage = U1RXREG;
		IFS0bits.U1RXIF = 0;

	}

	else {
	
		midiBuffer[putCounter] =	U1RXREG;
		putCounter++;
		if(putCounter == BUFFER_SIZE) {
			putCounter = 0;
		}
	
		IFS0bits.U1RXIF =0;
	
	}

}


void _DefaultInterrupt(void){
      while(1);
 }


void __attribute__ ((interrupt, no_auto_psv)) _T1Interrupt(void)
{
	
	IFS0bits.T1IF = 0; /* Clear Left Channel Interrupt Flag */
	
	if(PORTBbits.RB9){
		sendNextChannelAlso = 0;
	}
	else sendNextChannelAlso = 1;

	midiChannelNumber = ((PORTB & 0b11)<<2) + (PORTA & 0b11);
	midiChannelNumber ^= 0b1111;

	LATBbits.LATB15 ^= 1;

}



inline void ProcessMidi(){

	if(midiByteToProcess & 128){		//STATUS MESSAGE

		//status messages that are bigger or equal to 0xF0
		//are system messages, not channel messages
		//This includes things such as timing clocks and Start/Stop
		//song messages

		if(midiByteToProcess >= 0xF0){

			sendingThisMessage = 1;
			U1TXREG = (0xff & midiByteToProcess);

			//WARNING!!! look at below - need to recheck
			sendingThisMessage = 0;
				
		}

		else if( (midiByteToProcess & 0x0f) == midiChannelNumber ){

			sendingThisMessage = 1;
			U1TXREG = (0xff & midiByteToProcess);

		}

		else if( (midiByteToProcess & 0x0f) == (midiChannelNumber+1) ){

			if(sendNextChannelAlso){

				sendingThisMessage = 1;
				U1TXREG = (0xff & midiByteToProcess);

			}

			else {
				sendingThisMessage = 0;		//not sending next ch
			}

		}

		else {
			sendingThisMessage = 0;
		}
		
	}
	

	else {		//databyte

		if(sendingThisMessage){
			U1TXREG = (0xff & midiByteToProcess);
		}

	}

}


void Init(){

	LATA = LATB = 0;
	PORTA = PORTB = 0;
	TRISA = TRISB = 0;

	ADPCFG = 0xff;		//Disable ADC inputs

	//MIDI Channel Switch Inputs
	TRISAbits.TRISA0 = 1;
	TRISAbits.TRISA1 = 1;
	TRISBbits.TRISB0 = 1;
	TRISBbits.TRISB1 = 1;

	//Enable weak pull-ups
	CNPU1bits.CN2PUE = 1;
	CNPU1bits.CN3PUE = 1;
	CNPU1bits.CN4PUE = 1;
	CNPU1bits.CN5PUE = 1;

	//Next Channel Switch Input
	TRISBbits.TRISB9 = 1;
	CNPU2bits.CN21PUE = 1;

	//Spare Switch Input
	TRISBbits.TRISB8 = 1;
	CNPU2bits.CN22PUE = 1;

	//Set RP7 as RX input
	RPINR18bits.U1RXR = 0b00111;
	TRISBbits.TRISB7 = 1;

	//RP14 is tied to UART Tx (00011)
	RPOR7bits.RP14R = 0b00011;	

	U1MODE = 0;
	U1BRG = 7;	
	/*	
		baud rate = Fcy / (16*(U1brg + 1))
		U1brg = ( Fcy / (16 * baud rate) ) - 1
	*/

	IFS0bits.U1RXIF = 0;
	IEC0bits.U1RXIE = 1;

	U1MODEbits.UARTEN = 1;
	U1STAbits.UTXEN = 1;		//must come after uarten

}

int main( void ){

	Init();

	TMR1 = T1CON = 0;

	T1CONbits.TCKPS = 0b01;

	IFS0bits.T1IF = 0; // Clear Timer1 Interrupt Flag
	IEC0bits.T1IE = 1; // Enable Timer1 interrupt

	asm("BSET T1CON, #15");//     ; Turn ON the module 

	garbage = U1RXREG;
	garbage = U1RXREG;
	garbage = U1RXREG;
	garbage = U1RXREG;
		
	while(1==1){
		
 		if(putCounter != getCounter){
			midiByteToProcess = midiBuffer[getCounter];
			getCounter++;
			if(getCounter==BUFFER_SIZE)	getCounter=0;

			ProcessMidi();
		}

		asm("PWRSAV 		#1");	//Sleep!

	}  

	return 0;
}