Mercurial > yubikey-lua / file diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/crc16/crc16.lua	Wed Feb 16 20:29:33 2011 +0000
@@ -0,0 +1,33 @@
+local bit = require "bit";
+
+module "crc16"
+
+function hash(str)
+	local crc;
+	
+	local function initCrc()
+		crc = 0xffff;
+	end
+	
+	local function updCrc(byte)
+		crc = bit.bxor(crc, byte);
+		for i=1,8 do
+			local j = bit.band(crc, 1);
+			crc = bit.rshift(crc, 1);
+			if j ~= 0 then
+				crc = bit.bxor(crc, 0x8408);
+			end
+		end
+	end
+
+	local function getCrc(str)
+		initCrc();
+		for i = 1, #str  do
+			updCrc(str:byte(i));
+		end
+		return crc;
+	end
+	return getCrc(str);
+end
+
+return { hash = hash }