crc8.lua

local M = {}
M.math = math
M.crc8_table = {
    0x00,0x5E,0xBC,0xE2,0x61,0x3F,0xDD,0x83,
    0xC2,0x9C,0x7E,0x20,0xA3,0xFD,0x1F,0x41,
    0x9D,0xC3,0x21,0x7F,0xFC,0xA2,0x40,0x1E,
    0x5F,0x01,0xE3,0xBD,0x3E,0x60,0x82,0xDC,
    0x23,0x7D,0x9F,0xC1,0x42,0x1C,0xFE,0xA0,
    0xE1,0xBF,0x5D,0x03,0x80,0xDE,0x3C,0x62,
    0xBE,0xE0,0x02,0x5C,0xDF,0x81,0x63,0x3D,
    0x7C,0x22,0xC0,0x9E,0x1D,0x43,0xA1,0xFF,
    0x46,0x18,0xFA,0xA4,0x27,0x79,0x9B,0xC5,
    0x84,0xDA,0x38,0x66,0xE5,0xBB,0x59,0x07,
    0xDB,0x85,0x67,0x39,0xBA,0xE4,0x06,0x58,
    0x19,0x47,0xA5,0xFB,0x78,0x26,0xC4,0x9A,
    0x65,0x3B,0xD9,0x87,0x04,0x5A,0xB8,0xE6,
    0xA7,0xF9,0x1B,0x45,0xC6,0x98,0x7A,0x24,
    0xF8,0xA6,0x44,0x1A,0x99,0xC7,0x25,0x7B,
    0x3A,0x64,0x86,0xD8,0x5B,0x05,0xE7,0xB9,
    0x8C,0xD2,0x30,0x6E,0xED,0xB3,0x51,0x0F,
    0x4E,0x10,0xF2,0xAC,0x2F,0x71,0x93,0xCD,
    0x11,0x4F,0xAD,0xF3,0x70,0x2E,0xCC,0x92,
    0xD3,0x8D,0x6F,0x31,0xB2,0xEC,0x0E,0x50,
    0xAF,0xF1,0x13,0x4D,0xCE,0x90,0x72,0x2C,
    0x6D,0x33,0xD1,0x8F,0x0C,0x52,0xB0,0xEE,
    0x32,0x6C,0x8E,0xD0,0x53,0x0D,0xEF,0xB1,
    0xF0,0xAE,0x4C,0x12,0x91,0xCF,0x2D,0x73,
    0xCA,0x94,0x76,0x28,0xAB,0xF5,0x17,0x49,
    0x08,0x56,0xB4,0xEA,0x69,0x37,0xD5,0x8B,
    0x57,0x09,0xEB,0xB5,0x36,0x68,0x8A,0xD4,
    0x95,0xCB,0x29,0x77,0xF4,0xAA,0x48,0x16,
    0xE9,0xB7,0x55,0x0B,0x88,0xD6,0x34,0x6A,
    0x2B,0x75,0x97,0xC9,0x4A,0x14,0xF6,0xA8,
    0x74,0x2A,0xC8,0x96,0x15,0x4B,0xA9,0xF7,
    0xB6,0xE8,0x0A,0x54,0xD7,0x89,0x6B,0x35,
};
	 M.get_crc8 = function(data) 
        function expl(dt)
            local m = {}
            for i = 1, #dt  do
                m[i] = string.byte(string.sub(dt,i,i))
            end
            return m
        end

        local dat = (expl(data))
        local crc = 0

        for i = 1, #dat do
            local dig = dat[i]
            crc = M.crc8_table[(bit.bxor(dig, crc))+1]
        end
        return crc
    end
	
	M.decode = function(data)
        local dat = data:sub(1, data:find("#")) or "Not#"
        local plc = data:find("#") or -1
        local crc = tonumber(data:sub(plc+1))
		local control = M.get_crc8(dat)
		if crc == control then
			-- print('Good!')
		    local pl = data:find("}") or data:find("#")
            local dt = data:sub(1, pl)
			return dt;
		else 
			-- print('Bad!')
			return 'NoCRC'
		end
	end

	M.encode = function(data)
		local first
		first = tostring(M.math.random(0,255))
		local part = data..first..'#'
		local fin = M.get_crc8(part)
		local all = part..fin
		return all 
	end
	
return M