makeSamples.js

// Code in ~2 hours by Bemmu, idea and sound code snippet from Viznut.

var functionParams = {
    eightBit: false,
    unsigned:false,
    forBitmap: {
        sf:"127+127*(EXPR)",
        uf:"255*(EXPR)",
        s8:"127+(EXPR)",
        u8:'EXPR',
        sampler:function(str) {
            return functionParams.getSampler(str, this);
        }
    },
    forAudio:{
        sf:'EXPR',
        uf:'2*(EXPR)-1',
        s8:'((EXPR)&255)/128',
        u8:'((EXPR)&255)/128 - 1',
        sampler:function(str) {
            return functionParams.getSampler(str, this);
        }
    },
    toCode:function() {return (this.unsigned? 'u' : 's' ) + (this.eightBit? '8' : 'f')},
    getSampler: function(str, targetType) {
        var code = this.toCode();
        var fragment = targetType[code];
        return makeBulkSampler(str, fragment);
    }
};


var replacements = {
    sin: "Math.sin",
    cos: "Math.cos",
    tan: "Math.tan",
    floor: "Math.floor",
    ciel: "Math.ceil",
    pi:"Math.PI",
    round:"Math.round"
};

function preprocessFunction(oneLiner) {

    for (var key in replacements) {
        oneLiner = oneLiner.replace(RegExp(key, 'g'), replacements[key]);
    }
    return oneLiner;
}


function makeBulkSampler(rawOneLiner, conversionTemplate) {
    var oneLiner = preprocessFunction(rawOneLiner);
    var ourExpression = conversionTemplate.replace("EXPR",oneLiner);
    var wrapper = "var f = function (buf,count,t) {for(var i=0; i<count;i++,t++)buf[i]=(EXPR);}";
    var toEval = wrapper.replace('EXPR',ourExpression);
    return makeFunction(toEval) || nullFunction;
}

function makeBulkSampleFunction(rawOneLiner) {
    return functionParams.forAudio.sampler(rawOneLiner);
//    var oneLiner = preprocessFunction(rawOneLiner);
//    //  if(!makeFunction(oneLiner)) return null;
//
//
//    var toEval = "var f = function (buf,count,t) {for(i=0; i<count;i++,t++) {buf[i]=(" + oneLiner + ");}}";
//    return makeFunction(toEval) || nullFunction;
}

function makeBulkSample8BitFunction(rawOneLiner) {
    var oneLiner = preprocessFunction(rawOneLiner);
    //  if(!makeFunction(oneLiner)) return null;
    var toEval = "var f =function(buf,count,t){for(i=0; i<count;i++,t++)buf[i]=127+127*(" + oneLiner + ");};"
    return makeFunction(toEval) || nullFunction;
}


function makeFunction(evalString) {
    try {
        eval(evalString);
    } catch(e) {
        return null;
    }
    return f;
}
function nullFunction() {
    return 1;
}


function makeSampleFunction(rawOneLiner) {
    try {
        var oneLiner = preprocessFunction(rawOneLiner);
         eval("var f = function (t) { return " + oneLiner + "}");
        return f;
       } catch(e) {
        if(elt) elt.innerHTML = e.toString();
        return null;
    }
}


function generateSound(f, seconds, frequency, bitsPerSample, channels) {
    var count = frequency * seconds * channels;
    var sampleArray = bitsPerSample == 16 ? new Int16Array(count) : new Uint8Array(count);


    for (var t = 0; t < count; t++) {
        var sample = f(t) & 0xff;
        sampleArray[t] = sample << 8 | sample;
    }
    return sampleArray;
}

var backBuffer;

function genSound16x1(f, count) {
    backBuffer = new ArrayBuffer(count * 2);
    var sampleArray = new Int16Array(backBuffer);

    for (var t = 0; t < count; t++) {
        sampleArray[t] = ((f(t) * 256) % 0xffff) - 32768;
    }
    return sampleArray;
}

var sampleHelper = {
    samples8: null,
    makeSampleData8: function(sampleFunction, wd, ht) {

        var sampleCount = wd * ht;
        this.samples8 = this.samples8 || new Uint8Array(sampleCount);
        var s = this.samples8;

        for (var t = 0; t < sampleCount; t++) {
            s[t] = 127 + 127 * sampleFunction(t);
        }
        return this.samples8;
    }
}

function makeSampleData(sampleFunction) {
    var bitsPerSample = 16;
    var frequency = 44100;
    var channels = 1;
    var duration = 10;
    var sampleCount = duration * channels * frequency;
    return genSound16x1(sampleFunction, sampleCount);

//    return generateSound(sampleFunction,30,frequency,bitsPerSample,channels);

}
function makeRiff(samples) {
    var bitsPerSample = 16;
    var frequency = 44100;
    var channels = 1;
    return RIFFChunk(channels, bitsPerSample, frequency, samples);
}