// Matthew Ito, Jsoon Kim
// Generates DDS signal, as well as gathering data from the SNES

#include <Mega32.h>
#include <delay.h>
#include <math.h>

#include "dpcmtable.h"

#define maxkeys 12
#define countMS 62  //ticks/mSec

#define t1 625 //10 ms
#define t2 8 // division for speech generation on PWM

#define begin {
#define end }

//accumulator 1
unsigned long accumulator1 @0x2f0;
unsigned char highbyte1 @0x2f3;

//accumulator 2
unsigned long accumulator2 @0x2f4;
unsigned char highbyte2 @0x2f7;

//incrementers
unsigned long increment1;
unsigned long increment2;

unsigned int outI, tableI;      	//indexes
char cycle ;  			//decode phase counter
char out, lastout;		//output values
char p1, p2, p3, p4	 ;	//hold 4 differentials
char packed	;			//byte containing 4 2-bit values
int TableSize;

//DTMF tone select
unsigned char DTMF_select;
//DPCM sound select
unsigned char DPCM_select;
//DTMF/DPCM output select, 1=DTMF, 0=DPCM
unsigned char DTMForDPCM;

//SNES counter variable and buffer
unsigned int snes_buffer, snes_counter;

//last sound command input
unsigned char lastSoundInput;

//counter variable
int i;

int time1; //task1 timer
int time2;  //voice timer - does virtual offset of 8

//sine table
char sineTable[256] @0x300;  //need loc to avoid glitch

//reconstruction PCMvalues
flash char PCMvalue[4] = {-20, -4, 4, 20};

//init function
void initialize(void);

//DPCM sound control
void DPCM(void);

//DTMF tone control
void DTMF(void);

//increments given for the various frequencies
//1477 hz = 60CBF2B
//1336 hz = 578E5C5
//1209 hz = 4F3BA77
//941 hz = 3DAB5C4
//852 hz = 37D6302
//770 hz = 327674D
//697 hz = 2DADB83
flash unsigned long inctbl[7] = {0x060CBF2B, 0x0578E5C5, 0x04F3BA77, 0x03DAB5C4, 0x037D6302, 0x0327674D, 0x02DADB83};

//read SNES controller
void getSNES(void);

interrupt [TIM0_OVF] void sgen(void)
begin 
    //decrement virtual timer
    if(time1 > 0) time1--;

	 if (DTMForDPCM)
    begin
   	  //the DDS code and scaling
	  accumulator1 = accumulator1 + increment1;
	  accumulator2 = accumulator2 + increment2;
	  OCR0 = 128 + sineTable[highbyte1] + sineTable[highbyte2];
	 end
	 else if(--time2==0)
    begin
      //reportVdec(tableI);
      time2=8;
    	cycle = outI%4;
    	if (cycle==0) //unpack next byte
    	begin
            packed = dpcmtable[tableI];
            p1 = (packed & 192)>>6;
            p2 = (packed & 48)>>4;
            p3 = (packed & 12)>>2;
            p4 = (packed & 3);
            tableI++;
     	    //compute the output and send to PWM
            out = lastout + PCMvalue[p1] - lastout>>4 ;
     	end
     	else if (cycle==1)
    	    out = lastout + PCMvalue[p2] - lastout>>4 ;
      else if (cycle==2)
          out = lastout + PCMvalue[p3] - lastout>>4 ;
      else if (cycle==3)
      	 out = lastout + PCMvalue[p4] - lastout>>4 ;

    	//update outputs
    	OCR0 = out;
      lastout = out;
      outI++;
      if (tableI==TableSize)
      begin
         //set to DTMF on constant signal
         increment1 = 0;
         increment2 = 0;
         DTMForDPCM = 1;
      end
	 end
end

void main(void)
  {
    //trigger timer0 interrupt on overflow
    TIMSK = 0b00000001;

    //B.3 : OC0 sound signal : output
    //B.4 : SNES clk : output
    //B.5 : SNES latch : output
    //B.6 : SNES data : input
    DDRB = 0b00111000;
    
    //activate PWM
    increment1 = 0x00000000;
    accumulator1 = 0;
    increment2 = 0x00000000;
    accumulator2 = 0;
    
    //setup timer0, OC0 interrupt
    TCNT0 = 0;
    OCR0 = 0;
    TCCR0 = 0b01101001;
    
    //init sound gen variables
    lastout = 128;
    time2 = t2;

    //init the sine table
    for (i=0; i<256; i++)
    begin
   		sineTable[i] = (char)(63.0 * sin(6.283*((float)i)/256.0));
    end
    
    //output snesbuffer, input sound control
    //A.7 = N (128)
    //A.6 = S (64)
    //A.5 = W (32)
    //A.4 = E (16)
    //A.3 = A (8)
    //A.2 = X (4)
    //A.1 = sound select
    //A.0 = sound select
    DDRA = 0b11111100;
    
    #asm("sei"); //enable interrupts


    while(1)
    begin
        if(time1==0)
        begin
        time1 = t1;
        getSNES();
        
        //load buffer onto portA
        PORTA = snes_buffer;
        
        //if sound input is not the same as last input start new sound
        if(lastSoundInput != (PINA.1<<1)+PINA.0)
        begin
           lastSoundInput = (PINA.1<<1)+PINA.0;
           DPCM_select = lastSoundInput;
           DPCM();
        end
        
        end 
    end
end

//read SNES controller
void getSNES(void)
begin
    snes_counter = 0;
    while(snes_counter < 24)
    begin
      //delay
      #asm 
        nop nop nop nop
      #endasm
      snes_counter++;
      //process latch
      if (snes_counter==1)
        PORTB.5 = 1; //latch high
      else if (snes_counter==2)
      begin
        snes_buffer = ~PINB.6; //read first button
        PORTB.5 = 0; //latch low
      end
      else
        begin
        if(snes_counter%2) //pulse clk line
          PORTB.4 = 1;
        else
        begin
          snes_buffer = (snes_buffer<<1)|~PINB.6; //read
          PORTB.4 = 0;
        end
      end
    end
end

//DPCM sound generation
//dictates the initial start point of the array
//of values, as well as the end point
//then generates DDS
void DPCM(void)
begin
	 switch(DPCM_select)
	 begin
	   case 1:  //incoming
	   TableSize = 1619;
	   outI = 0;
	   tableI = 0;
	   DTMForDPCM = 0;
	   break;
	   case 2:  //target neutralized
	   TableSize = 4279;
	   outI = 0;
	   tableI = 1620;
	   DTMForDPCM = 0;
	   break;
	   case 3:  //force silence
	   //set to DDS on constant signal
       increment1 = 0;
       increment2 = 0;
       DTMForDPCM = 1;
	   break;
	 end
end

//DTMF tone generation --not used, but available for use to generate
//DTMF tones, if desired
void DTMF(void)
begin
    switch(DTMF_select)
    begin
       case 1:  //represents 1
       increment1 = inctbl[2];
       increment2 = inctbl[6];
       break;
       case 2:  //represents 2
       increment1 = inctbl[1];
       increment2 = inctbl[6];
       break;
       case 3:  //represents 3
       increment1 = inctbl[0];
       increment2 = inctbl[6];
       break;
       case 4:  //represents 4
       increment1 = inctbl[2];
       increment2 = inctbl[5];
       break;
       case 5:  //represents 5
       increment1 = inctbl[1];
       increment2 = inctbl[5];
       break;
       case 6:  //represents 6
       increment1 = inctbl[0];
       increment2 = inctbl[5];
       break;
       case 7:  //represents 7
       increment1 = inctbl[2];
       increment2 = inctbl[4];
       break;
       case 8: //represents 8
       increment1 = inctbl[1];
       increment2 = inctbl[4];
       break;
       case 9: //represents 9
       increment1 = inctbl[0];
       increment2 = inctbl[4];
       break;
       case 0: //represents 0
       increment1 = inctbl[1];
       increment2 = inctbl[3];
       break;
       default:
       increment1 = 0;
       increment2 = 0;
       break;
    end
end