1 files changed, 169 insertions, 0 deletions
diff --git a/src/js/lib/int64.js b/src/js/lib/int64.js
new file mode 100644
index 0000000..1ef5910
--- /dev/null
+++ b/src/js/lib/int64.js
@@ -0,0 +1,169 @@
+//
+// Tiny module that provides big (64bit) integers.
+//
+// Copyright (c) 2016 Samuel Groß
+//
+// Requires utils.js
+//
+
+// Datatype to represent 64-bit integers.
+//
+// Internally, the integer is stored as a Uint8Array in little endian byte order.
+function Int64(v) {
+	// The underlying byte array.
+	var bytes = new Uint8Array(8);
+
+	switch (typeof v) {
+		case 'number':
+			v = '0x' + Math.floor(v).toString(16);
+		case 'string':
+			if (v.startsWith('0x'))
+				v = v.substr(2);
+			if (v.length % 2 == 1)
+				v = '0' + v;
+
+			var bigEndian = unhexlify(v, 8);
+			bytes.set(Array.from(bigEndian).reverse());
+			break;
+		case 'object':
+			if (v instanceof Int64) {
+				bytes.set(v.bytes());
+			} else {
+				if (v.length != 8)
+					throw TypeError("Array must have excactly 8 elements.");
+				bytes.set(v);
+			}
+			break;
+		case 'undefined':
+			break;
+		default:
+			throw TypeError("Int64 constructor requires an argument.");
+	}
+
+	// Return a double whith the same underlying bit representation.
+	this.asDouble = function() {
+		// Check for NaN
+		if (bytes[7] == 0xff && (bytes[6] == 0xff || bytes[6] == 0xfe))
+			throw new RangeError("Integer can not be represented by a double");
+
+		return Struct.unpack(Struct.float64, bytes);
+	};
+
+	// Return a javascript value with the same underlying bit representation.
+	// This is only possible for integers in the range [0x0001000000000000, 0xffff000000000000)
+	// due to double conversion constraints.
+	this.asJSValue = function() {
+		if ((bytes[7] == 0 && bytes[6] == 0) || (bytes[7] == 0xff && bytes[6] == 0xff))
+			throw new RangeError("Integer can not be represented by a JSValue");
+
+		// For NaN-boxing, JSC adds 2^48 to a double value's bit pattern.
+		this.assignSub(this, 0x1000000000000);
+		var res = Struct.unpack(Struct.float64, bytes);
+		this.assignAdd(this, 0x1000000000000);
+
+		return res;
+	};
+
+	// Return the underlying bytes of this number as array.
+	this.bytes = function() {
+		return Array.from(bytes);
+	};
+
+	// Return the byte at the given index.
+	this.byteAt = function(i) {
+		return bytes[i];
+	};
+
+	// Return the value of this number as unsigned hex string.
+	this.toString = function() {
+		return '0x' + hexlify(Array.from(bytes).reverse());
+	};
+
+	// Basic arithmetic.
+	// These functions assign the result of the computation to their 'this' object.
+
+	// Decorator for Int64 instance operations. Takes care
+	// of converting arguments to Int64 instances if required.
+	function operation(f, nargs) {
+		return function() {
+			if (arguments.length != nargs)
+				throw Error("Not enough arguments for function " + f.name);
+			for (var i = 0; i < arguments.length; i++)
+				if (!(arguments[i] instanceof Int64))
+					arguments[i] = new Int64(arguments[i]);
+			return f.apply(this, arguments);
+		};
+	}
+
+	// this = -n (two's complement)
+	this.assignNeg = operation(function neg(n) {
+		for (var i = 0; i < 8; i++)
+			bytes[i] = ~n.byteAt(i);
+
+		return this.assignAdd(this, Int64.One);
+	}, 1);
+
+	// this = a + b
+	this.assignAdd = operation(function add(a, b) {
+		var carry = 0;
+		for (var i = 0; i < 8; i++) {
+			var cur = a.byteAt(i) + b.byteAt(i) + carry;
+			carry = cur > 0xff | 0;
+			bytes[i] = cur;
+		}
+		return this;
+	}, 2);
+
+	// this = a - b
+	this.assignSub = operation(function sub(a, b) {
+		var carry = 0;
+		for (var i = 0; i < 8; i++) {
+			var cur = a.byteAt(i) - b.byteAt(i) - carry;
+			carry = cur < 0 | 0;
+			bytes[i] = cur;
+		}
+		return this;
+	}, 2);
+
+	// this = a ^ b
+	this.assignXor = operation(function sub(a, b) {
+		for (var i = 0; i < 8; i++) {
+			bytes[i] = a.byteAt(i) ^ b.byteAt(i);
+		}
+		return this;
+	}, 2);
+}
+
+// Constructs a new Int64 instance with the same bit representation as the provided double.
+Int64.fromDouble = function(d) {
+	var bytes = Struct.pack(Struct.float64, d);
+	return new Int64(bytes);
+};
+
+// Convenience functions. These allocate a new Int64 to hold the result.
+
+// Return -n (two's complement)
+function Neg(n) {
+	return (new Int64()).assignNeg(n);
+}
+
+// Return a + b
+function Add(a, b) {
+	return (new Int64()).assignAdd(a, b);
+}
+
+// Return a - b
+function Sub(a, b) {
+	return (new Int64()).assignSub(a, b);
+}
+
+// Return a ^ b
+function Xor(a, b) {
+	return (new Int64()).assignXor(a, b);
+}
+
+// Some commonly used numbers.
+Int64.Zero = new Int64(0);
+Int64.One = new Int64(1);
+
+// That's all the arithmetic we need for exploiting WebKit.. :)