File content as of revision 10:59c829586a4f:

#include "mbed.h"
#include "sintable.h"

AnalogOut outMono(PA_4);//Not labeled in the docs for the f401, but seems to be for all
//AnalogOut DAC1(PA_5);

AnalogIn inVol(PA_0);
AnalogIn inModAmt(PA_1);
//AnalogIn ADC2(PA_2);//these are the uart pins!!
//AnalogIn ADC3(PA_3);//these are the uart pins!!
//AnalogIn ADC4(PA_4);//we're using these for output
//AnalogIn ADC5(PA_5);//we're using these for output
AnalogIn inCarA(PA_6);
AnalogIn inCarD(PA_7);
//AnalogIn ADC8(PB_0);//lets leave the 2 we aren't using in a single port
//AnalogIn ADC9(PB_1);//that way we know there's not ADCs on one of them
AnalogIn inCarS(PC_0);
AnalogIn inCarR(PC_1);
AnalogIn inModA(PC_2);
AnalogIn inModD(PC_3);
AnalogIn inModS(PC_4);
AnalogIn inModR(PC_5);

//BusIn keyBank(PC_10, PC_11, PC_12, PC_13, PD_2, PH_1); old
BusIn keyBank(PH_1, PD_2, PC_13, PC_12, PC_11, PC_10);
BusOut bankSelect(PB_0, PB_1, PB_2, PB_3, PB_4, PB_5, PB_6, PB_7, PB_8);
BusIn numerator(PA_8, PA_9, PA_10, PA_11);
BusIn denominator(PA_12, PA_13, PA_14, PA_15);

Serial pc(USBTX, USBRX);

Ticker synthesisClock;

#define numKeys 49

//constants
const int carrierIncrements[] = {107, 113, 120, 127, 135, 143, 151, 160, 170, 
    180, 190, 202, 214, 227, 240, 254, 270, 286, 303, 321, 340, 360, 381, 404, 
    428, 454, 481, 509, 540, 572, 606, 642, 680, 720, 763, 809, 857, 908, 962, 
    1019, 1080, 1144, 1212, 1284, 1360, 1441, 1527, 1618, 1714};
const int attackLimit = (0x1 << 16) - 1;
#define U_PI 3.14159265358979
const int fixed2pi = (2.0 * U_PI) * (0x1 << 16l);

//non-constants
//Most of these will be recalculated or reset on every input cycle of the main
//  loop, as appropriate
int FMmult;
int Volume;
int modVol;
int modAmpI;
int carAmpS;
int64_t keyboard;
int carrierPhases[numKeys];
int modulatorPhases[numKeys];
short envelopeStatesC[numKeys];
short envelopeStatesM[numKeys];
int envelopeAmpsC[numKeys];
int envelopeAmpsM[numKeys];

int modA;
int modD;
int modS;
int modR;
int carA;
int carD;
int carS;
int carR;

int fastSin(const int phase){
    int index = (phase & 0x3ffc) >> 2;
    int subindex = phase & 0x3;
    int quadrant = (phase & 0xc000) >> 14;
    int sum = 0;
    switch (quadrant) {
        case 0:
            sum += (4 - subindex) * sinTable[index];
            sum += subindex * sinTable[index+1];
            break;
        case 1:
            sum += (4 - subindex) * sinTable[1+4095-index];
            sum += subindex * sinTable[4095-index];
            break;
        case 2:
            sum -= (4 - subindex) * sinTable[index];
            sum -= subindex * sinTable[index+1];        
            break;
        case 3:
            sum -= (4 - subindex) * sinTable[1+4095-index];
            sum -= subindex * sinTable[4095-index];
            break;
    }
    sum = sum >> 2;
    
    return sum;
}

void synthesize(){
    carAmpS = 0;
    for(int i = 0; i < numKeys; ++i){
        if(keyboard & (0x1 << i)){
            if(envelopeStatesC[i] < 2)
                envelopeStatesC[i] = 4;
            if(envelopeStatesM[i] < 2)
                envelopeStatesM[i] = 4;
            
            if(envelopeStatesC[i] == 4){
                envelopeAmpsC[i] += carA;
                if(envelopeAmpsC[i] >= attackLimit){
                    envelopeAmpsC[i] = attackLimit;
                    envelopeStatesC[i] = 3;
                }
            }
            
            if(envelopeStatesM[i] == 4){
                envelopeAmpsM[i] += modA;
                if(envelopeAmpsM[i] >= attackLimit){
                    envelopeAmpsM[i] = attackLimit;
                    envelopeStatesM[i] = 3;
                }
            }
            
            if(envelopeStatesC[i] == 3){
                envelopeAmpsC[i] += carD;
                if(envelopeAmpsC[i] <= carS){
                    envelopeAmpsC[i] = carS;
                    envelopeStatesC[i] = 2;
                }
            }

            if(envelopeStatesM[i] == 3){
                envelopeAmpsM[i] += modD;
                if(envelopeAmpsM[i] <= modS){
                    envelopeAmpsM[i] = modS;
                    envelopeStatesM[i] = 2;
                }
            }
        }else{
            if(envelopeStatesC[i] > 1)
                envelopeStatesC[i] = 1;
            if(envelopeStatesM[i] > 1)
                envelopeStatesM[i] = 1;
                
            if(envelopeStatesC[i] == 1){
                if(envelopeAmpsC[i] <= 0){
                    envelopeStatesC[i] = 0;
                    envelopeAmpsC[i] = 0;
                }else{
                    envelopeAmpsC[i] -= carR;
                }
            }
            if(envelopeStatesM[i] == 1){
                if(envelopeAmpsM[i] <= 0){
                    envelopeStatesM[i] = 0;
                    envelopeAmpsM[i] = 0;
                }else{
                    envelopeAmpsM[i] -= modR;
                }
            }            
        }
        
        if(envelopeAmpsC[i] > 0){
            modulatorPhases[i] += (FMmult * carrierIncrements[i]) >> 16;
            modAmpI = fastSin((((modulatorPhases[i] * envelopeAmpsM[i]) >> 16)
                * modVol) >> 16);
            carrierPhases[i] += ((carrierIncrements[i] + modAmpI) * fixed2pi) >> 16;
            carAmpS += (fastSin(carrierPhases[i]) * envelopeAmpsC[i]) >> 16;
        }
    }
    outMono.write_u16(((carAmpS / numKeys) * Volume) >> 16);
}


int main() {
    int ratNumer;
    int ratDenom;
    
    int64_t keytemp = 0;

    FMmult = 1;
    Volume = 0;
    modVol = 0;
    modAmpI = 0;
    carAmpS = 0;
    keyboard = 0ll;
    for(int i = 0; i < numKeys; ++i){
        carrierPhases[i] = 0;
        modulatorPhases[i] = 0;
        envelopeStatesC[i] = 0;
        envelopeStatesM[i] = 0;
        envelopeAmpsC[i] = 0;
        envelopeAmpsM[i] = 0;
    }
    modA = 0;
    modD = 0;
    modS = 0;
    modR = 0;
    carA = 0;
    carD = 0;
    carS = 0;
    carR = 0;
    
    keyBank.mode(PullNone);
    synthesisClock.attach(synthesize, 0.000025);
    
    while(true){
        ratNumer = 0xf & ~ numerator;
        ratDenom = 0xf & ~ denominator;
        FMmult = (ratNumer << 16) / ratDenom;
        
        Volume = (int)inVol.read_u16();
        modVol = (int)inModAmt.read_u16();
        
        if(! inCarA.read_u16())
            carA = 0xffff;
        else
            carA = 0xffff / ((int)inCarA.read_u16());
        
        if(! inCarD.read_u16())
            carD = 0xffff;
        else
            carD = 0xffff / ((int)inCarD.read_u16());
        
        carS = (int)inCarS.read_u16();
        
        if(! inCarR.read_u16())
            carR = 0xffff;
        else
            carR = 0xffff / ((int)inCarR.read_u16());
        
        if(! inModA.read_u16())
            modA = 0xffff;
        else
            modA = 0xffff / ((int)inModA.read_u16());
        
        if(! inModD.read_u16())
            modD = 0xffff;
        else
            modD = 0xffff / ((int)inModD.read_u16());
        
        modS = (int)inModS.read_u16();
        
        if(! inModR.read_u16())
            modR = 0xffff;
        else
            modR = 0xffff / ((int)inModR.read_u16());
        
        //THIS IS CORRECT (1 means the key is connected)
        //                 B8    B7    B6    B5    B4    B3    B2    B1  B0
        //               |----||----||----||----||----||----||----||----||
        //0000000000000001111111111111111111111111111111111111111111111111
        //
        //THIS IS NOT CORRECT (1 means the key is connected)
        //            B8    B7    B6    B5    B4    B3    B2    B1    B0
        //          |----||----||----||----||----||----||----||----||----|
        //0000000000111111111111111111111111111111111111111111111111100000
        //Thus, we need to subtract 5 from our shift
        keytemp = 0; //zero the keys before we start ORing on top of everything
        for(int i = 0; i < 9; ++i) {
            bankSelect = (~(1LL << i)) & (unsigned long long)bankSelect.mask();
            wait_us(200);
            int shiftOffset = 6LL * i;

    
            keytemp |= ((~(unsigned long long)keyBank) & (unsigned long long)keyBank.mask()) << (unsigned long long)shiftOffset;
        }
        keytemp >>= 5;
        
        keyboard = keytemp;
        wait_ms(5);
    }
}