ASR_tangibles/backend/osc-parser.js

// OSC parsing based on node-osc

module.exports = (function() {
    var jspack = require("jspack").jspack,

    decode = function(data) {
        var message = [],
        address = decodeString(data);
        data = address.data;

        if (address.value === "#bundle") {
            data = decodeBundle(data, message);
        } else if (data.length > 0) {
            data = decodeMessage(address, data, message);
        }

        return message;
    },

    decodeBundle = function(data, message) {
        var time = decodeTime(data),
        bundleSize,
        content;
        
        data = time.data;

        message.push("#bundle");
        message.push(time.value);

        while (data.length > 0) {
            bundleSize = decodeInt(data);
            data = bundleSize.data;

            content = data.slice(0, bundleSize.value);
            message.push(decode(content));

            data = data.slice(bundleSize.value, data.length);
        }

        return data;
    },

    decodeMessage = function(address, data, message) {
        message.push(address.value);

        var typeTags = decodeString(data);
        data = typeTags.data;
        typeTags = typeTags.value;

        if (typeTags[0] === ",") {
            for (var i = 1; i < typeTags.length; i++) {
                var arg = decodeByTypeTag(typeTags[i], data);
                data = arg.data;
                message.push(arg.value);
            }
        }

        return data;
    },

    decodeByTypeTag = function(typeTag, data) {
        switch (typeTag) {
            case "i":
                return decodeInt(data);
            case "f":
                return decodeFloat(data);
            case "s":
                return decodeString(data);
        }
    },

    decodeInt = function(data) {
        return {
            value: jspack.Unpack(">i", data.slice(0, 4))[0],
            data: data.slice(4)
        };
    },

    decodeString = function(data) {
        var end = 0;
        while (data[end] && end < data.length) {
            end++;
        }
        return {
            value: data.toString("ascii", 0, end),
            data: data.slice(Math.ceil((end + 1) / 4) * 4)
        };
    },

    decodeFloat = function(data) {
        return {
            value: jspack.Unpack(">f", data.slice(0, 4))[0],
            data: data.slice(4)
        };
    },

    decodeTime = function(data) {
        var time = jspack.Unpack(">LL", data.slice(0, 8)),
        seconds = time[0],
        fraction = time[1];
        return {
            value: seconds + fraction / 4294967296,
            data: data.slice(8)
        };
    };

    return {
        decode: decode
    };
}());