// Karplus Strong circuit simulator
// Copyright 2010 Les Hall

[[0, 1], [0, 1], [0, 1], [0, 1]] @=> int inputSwitches[][];  
[2, 2, 2, 2] @=> int gateSwitches[];


[[0, 0], [0, 4], [4, 8], [8, 8]] @=> int offsets[][];
int masks[4][2];
int inputs[4][2];
int gateOutputs[4];
float sum;
int c;
(Math.pow(2, 12) - 1) $ int => int bitMask;

SinOsc s => dac;
0.3 => s.gain;


while (true) {
    
    // generate masks
    for (int i; i<4; i++) {
        for (int j; j<2; j++) {
            (1 << offsets[i][j]) << inputSwitches[i][j] => masks[i][j];
        }
    }
    
    // find input values
    for (int i; i<4; i++) {
        for (int j; j<2; j++) {
            if (masks[i][j] & c) {
                true => inputs[i][j];
            } else {
                false => inputs[i][j];
            }
        }
    }
    
    // calculate outputs
    for (int i; i<4; i++) {
        if (gateSwitches[i] == 0) {
            !(inputs[i][0] | inputs[i][1]) => gateOutputs[i];
        }
        if (gateSwitches[i] == 1) {
            !(inputs[i][0] & inputs[i][1]) => gateOutputs[i];
        }
        if (gateSwitches[i] == 2) {
            (inputs[i][0] ^ inputs[i][1]) => gateOutputs[i];
        }
        if (gateSwitches[i] == 3) {
            (inputs[i][0] & inputs[i][1]) => gateOutputs[i];
        }
    }
    
    // sum the weighted output selections
    0 => sum;
    for (int i; i<4; i++) {
        Math.pow(2.0, -i) * gateOutputs[i] +=> sum;
    }
    
    // adjust the VCO
    200 + 200 * sum => s.freq;
    <<<c, sum, s.freq()>>>;
    
    1 +=> c;
    bitMask & c => c;
    250::ms => now;
}