OpenStreetMap images layer on Google Map

gistfile1.js

    map.mapTypes.set("OSM", new google.maps.ImageMapType({
        getTileUrl: function(coord, zoom) {
            var imagesPerUnit = Math.pow(2, zoom);

            // Stitch horizontaly:
            var x = coord.x < 0 ? imagesPerUnit + (coord.x % imagesPerUnit) : coord.x;
            var x = x >= imagesPerUnit ? 0 : x;

            // Do not stitch verticaly, if overflow -- don't show:
            if(coord.y < 0 || coord.y >= imagesPerUnit)
                return null;

            return "http://tile.openstreetmap.org/" + zoom + "/" + x + "/" + coord.y + ".png";
        },
        tileSize: new google.maps.Size(256, 256),
        name: "OSM",
        maxZoom: 18
    }));