Creating a crc8 function with lua

Question

Is there a simple algorithm to create a crc8 checksum from a table in lua? Polynomial should be x^8+x^5+x^4+1 (0x31) This algorithm will be used to check the UID of the DS28CM00 UID-chip. Here you can find a table returned by the chip (LS-byte last) :

table = {112,232,9,80,1,0,0}

Thanks for any help

Answer 1

For Lua 5.3+

local function crc8(t)
   local c = 0
   for _, b in ipairs(t) do
      for i = 0, 7 do
         c = c >> 1 ~ ((c ~ b >> i) & 1) * 0x8C
      end
   end
   return c
end

print(crc8{112, 232, 9, 80, 1, 0, 0})  --> 219
print(crc8{2, 0x1C, 0xB8, 1, 0, 0, 0}) --> 0xA2 as in example from AN-27

---

For Lua 5.2-

local function crc8(t)
   local c = 0
   for _, b in ipairs(t) do
      for i = 0, 7 do
         local c0 = c % 2
         local b0 = b % 2
         c = (c - c0) / 2
         b = (b - b0) / 2
         if c0 + b0 == 1 then
            c = c + 0x80 + (c % 16 < 8 and 8 or -8) + (c % 8 < 4 and 4 or -4)
         end
      end
   end
   return c
end