// from https://github.com/jehervy/node-virtual-gamepads/blob/master/lib/io.js

var io = {};

io["int"] = 4;
io["char"] = 1;
io["char*"] = 8;

io.UINPUT_IOCTL_BASE = "U".charCodeAt();

io._IOC_NONE = 0;
io._IOC_WRITE = 1;
io._IOC_READ = 2;

io._IOC_NRBITS = 8;
io._IOC_TYPEBITS = 8;

io._IOC_SIZEBITS = 14;
io._IOC_DIRBITS = 2;

io._IOC_NRMASK = (1 << io._IOC_NRBITS) - 1;
io._IOC_TYPEMASK = (1 << io._IOC_TYPEBITS) - 1;
io._IOC_SIZEMASK = (1 << io._IOC_SIZEBITS) - 1;
io._IOC_DIRMASK = (1 << io._IOC_DIRBITS) - 1;

io._IOC_NRSHIFT = 0;
io._IOC_TYPESHIFT = io._IOC_NRSHIFT + io._IOC_NRBITS;
io._IOC_SIZESHIFT = io._IOC_TYPESHIFT + io._IOC_TYPEBITS;
io._IOC_DIRSHIFT = io._IOC_SIZESHIFT + io._IOC_SIZEBITS;

io.sizeof = function(n) {
	switch (typeof n) {
		case "number":
			return n;
		case "string":
			return n.length;
		case "object":
			return n.length ? n.length : 0;
		case "undefined":
			return 0;
	}
};

io._IOC = function(dir, type, nr, size) {
	return (
		(dir << io._IOC_DIRSHIFT) |
		(type << io._IOC_TYPESHIFT) |
		(nr << io._IOC_NRSHIFT) |
		(size << io._IOC_SIZESHIFT)
	);
};

io._IOC_TYPECHECK = function(t) {
	return io.sizeof(t);
};

io._IO = function(type, nr) {
	return io._IOC(io._IOC_NONE, type, nr, 0);
};

io._IOR = function(type, nr, size) {
	return io._IOC(io._IOC_READ, type, nr, io._IOC_TYPECHECK(size));
};

io._IOW = function(type, nr, size) {
	return io._IOC(io._IOC_WRITE, type, nr, io._IOC_TYPECHECK(size));
};

io._IOWR = function(type, nr, size) {
	return io._IOC(
		io._IOC_READ | io._IOC_WRITE,
		type,
		nr,
		io._IOC_TYPECHECK(size)
	);
};

io._IOR_BAD = function(type, nr, size) {
	return io._IOC(io._IOC_READ, type, nr, io.sizeof(size));
};

io._IOW_BAD = function(type, nr, size) {
	return io._IOC(io._IOC_WRITE, type, nr, io.sizeof(size));
};

io._IOWR_BAD = function(type, nr, size) {
	return io._IOC(io._IOC_READ | io._IOC_WRITE, type, nr, io.sizeof(size));
};

/* used to decode ioctl numbers.. */
io._IOC_DIR = function(nr) {
	return (nr >> io._IOC_DIRSHIFT) & io._IOC_DIRMASK;
};

io._IOC_TYPE = function(nr) {
	return (nr >> io._IOC_TYPESHIFT) & io._IOC_TYPEMASK;
};

io._IOC_NR = function(nr) {
	return (nr >> io._IOC_NRSHIFT) & io._IOC_NRMASK;
};

io._IOC_SIZE = function(nr) {
	return (nr >> io._IOC_SIZESHIFT) & io._IOC_SIZEMASK;
};

module.exports = io;