1 files changed, 78 insertions, 0 deletions
diff --git a/src/js/utils.js b/src/js/utils.js
new file mode 100644
index 0000000..361e71d
--- /dev/null
+++ b/src/js/utils.js
@@ -0,0 +1,78 @@
+//
+// Utility functions.
+//
+// Copyright (c) 2016 Samuel Groß
+//
+
+// Return the hexadecimal representation of the given byte.
+function hex(b) {
+	return ('0' + b.toString(16)).substr(-2);
+}
+
+// Return the hexadecimal representation of the given byte array.
+function hexlify(bytes) {
+	var res = [];
+	for (var i = 0; i < bytes.length; i++)
+		res.push(hex(bytes[i]));
+
+	return res.join('');
+}
+
+// Return the binary data represented by the given hexdecimal string.
+function unhexlify(hexstr) {
+	if (hexstr.length % 2 == 1)
+		throw new TypeError("Invalid hex string");
+
+	var bytes = new Uint8Array(hexstr.length / 2);
+	for (var i = 0; i < hexstr.length; i += 2)
+		bytes[i/2] = parseInt(hexstr.substr(i, 2), 16);
+
+	return bytes;
+}
+
+function hexdump(data) {
+	if (typeof data.BYTES_PER_ELEMENT !== 'undefined')
+		data = Array.from(data);
+
+	var lines = [];
+	for (var i = 0; i < data.length; i += 16) {
+		var chunk = data.slice(i, i+16);
+		var parts = chunk.map(hex);
+		if (parts.length > 8)
+			parts.splice(8, 0, ' ');
+		lines.push(parts.join(' '));
+	}
+
+	return lines.join('\n');
+}
+
+// Simplified version of the similarly named python module.
+var Struct = (function() {
+	// Allocate these once to avoid unecessary heap allocations during pack/unpack operations.
+	var buffer      = new ArrayBuffer(8);
+	var byteView    = new Uint8Array(buffer);
+	var uint32View  = new Uint32Array(buffer);
+	var float64View = new Float64Array(buffer);
+
+	return {
+		pack: function(type, value) {
+			var view = type;        // See below
+			view[0] = value;
+			return new Uint8Array(buffer, 0, type.BYTES_PER_ELEMENT);
+		},
+
+		unpack: function(type, bytes) {
+			if (bytes.length !== type.BYTES_PER_ELEMENT)
+				throw Error("Invalid bytearray");
+
+			var view = type;        // See below
+			byteView.set(bytes);
+			return view[0];
+		},
+
+		// Available types.
+		int8:    byteView,
+		int32:   uint32View,
+		float64: float64View
+	};
+})();