CHG: extracted a #define for the crc16 poly

[proxmark3-svn] / client / lualibs / precalc.lua

diff --git a/client/lualibs/precalc.lua b/client/lualibs/precalc.lua
index 284c8b628a7156c843787d5c80d456376fbaef54..ce58998a86eeed8522c8ab2754dea76338a78571 100644 (file)
--- a/client/lualibs/precalc.lua
+++ b/client/lualibs/precalc.lua
@@ -35,19 +35,10 @@ shifts[9]= { 0xD, 0xB, 0x0, 0x6, 0x6, 0x0, 0xB, 0xD, 0xA, 0xC, 0x7, 0x1, 0x1, 0x
 shifts[10]= { 0xe, 0x1, 0x1, 0xe, 0x1, 0xe, 0xe, 0x1, 0x1, 0xe, 0xe, 0x1, 0xe, 0x1, 0x1, 0xe }
 
 local function ApplyPermutationAndShifts( pos, value, nibble)
-       local el2bytes = shifts[pos]
-       local el2 = el2bytes[nibble+1] --one indexed
-       local shiftInit = el2bytes[1]
-       local permrow   = perm[shiftInit+1]
-       local j = 1
-       for i = 1,16 do
-               if permrow[i] == el2 then
-                       j = i
-                       break 
-               end
-       end
-       local rsbytes = perm[value+1]
-       local rs = rsbytes[j]
+       local shiftbytes = shifts[pos]
+       local shiftElem = shiftbytes[nibble+1] --one indexed
+       local shiftOne = shiftbytes[1]
+       local rs = bit32.bxor(value, bit32.bxor(shiftOne, shiftElem))
        return rs
 end