Bitwise operator module for Lua in plain Lua

bitwise.lua

local MAX = 64

function tobit(n)
   local ret = {}
   for i=MAX-1,0,-1 do
      if n / 2^i >= 1 then
         ret[i+1] = 1
         n = n % 2^i
      else
         ret[i+1] = 0
      end
   end
   return ret
end

function tonum(b)
   local ret = 0
   for i=0,MAX-1 do
      ret = ret + b[i+1] * 2^i
   end
   return ret
end

function lshift(n, b)
   return n * 2^b
end

function rshift(n, b)
   return n / 2^b
end

function band(n, m)
   local ret = {}
   local n, m = tobit(n), tobit(m)
   for i=1,MAX do
      ret[i] = (n[i] == 1 and m[i] == 1) and 1 or 0
   end
   return tonum(ret)
end

function bor(n, m)
   local ret = {}
   local n, m = tobit(n), tobit(m)
   for i=1,MAX do
      ret[i] = (n[i] == 1 or m[i] == 1) and 1 or 0
   end
   return tonum(ret)
end

assert(tonum(tobit(15)) == 15)
assert(lshift(0x1, 1) == 0x2)
assert(rshift(0x2, 1) == 0x1)
assert(band(0xF, 0x1) == 0x1)
assert(band(0xF, 0x2) == 0x2)
assert(band(0x10,0xF) == 0x0)
assert(bor(0x1, 0x2) == 0x3)