Merge pull request #2 from Positive07/patch-1

Use BitOp or Bit32 libraries where available

md5.lua

@@ -33,15 +33,23 @@ local md5 = {
 local floor, abs, max = math.floor, math.abs, math.max
 local char, byte, format, rep, sub =
   string.char, string.byte, string.format, string.rep, string.sub
+local bit_or, bit_and, bit_not, bit_xor, bit_rshift, bit_lshift
 
-local function check_int(n)
+local ok, bit = pcall(require, 'bit')
+if not ok then ok, bit = pcall(require, 'bit32') end
+
+if ok then
+  bit_or, bit_and, bit_not, bit_xor = bit.bor, bit.band, bit.bnot, bit.bxor
+  bit_rshift, bit_lshift = bit.rshift, bit.lshift
+else
+  local function check_int(n)
     -- checking not float
     if(n - floor(n) > 0) then
       error("trying to use bitwise operation on non-integer!")
     end
-end
+  end
   
-local function tbl2number(tbl)
+  local function tbl2number(tbl)
     local n = #tbl
   
     local rslt = 0
@@ -52,9 +60,9 @@ local function tbl2number(tbl)
     end
   
     return rslt
-end
+  end
   
-local function expand(tbl_m, tbl_n)
+  local function expand(tbl_m, tbl_n)
     local big = {}
     local small = {}
     if(#tbl_m > #tbl_n) then
@@ -69,11 +77,11 @@ local function expand(tbl_m, tbl_n)
       small[i] = 0
     end
   
-end
+  end
   
-local to_bits -- needs to be declared before bit_not
+  local to_bits -- needs to be declared before bit_not
   
-local function bit_not(n)
+  function bit_not(n)
     local tbl = to_bits(n)
     local size = max(#tbl, 32)
     for i = 1, size do
@@ -84,10 +92,10 @@ local function bit_not(n)
       end
     end
     return tbl2number(tbl)
-end
+  end
   
--- defined as local above
+  -- defined as local above
-to_bits = function (n)
+  to_bits = function (n)
     check_int(n)
     if(n < 0) then
       -- negative
@@ -108,9 +116,9 @@ to_bits = function (n)
     end
   
     return tbl
-end
+  end
   
-local function bit_or(m, n)
+  function bit_or(m, n)
     local tbl_m = to_bits(m)
     local tbl_n = to_bits(n)
     expand(tbl_m, tbl_n)
@@ -126,9 +134,9 @@ local function bit_or(m, n)
     end
   
     return tbl2number(tbl)
-end
+  end
   
-local function bit_and(m, n)
+  function bit_and(m, n)
     local tbl_m = to_bits(m)
     local tbl_n = to_bits(n)
     expand(tbl_m, tbl_n)
@@ -144,9 +152,9 @@ local function bit_and(m, n)
     end
   
     return tbl2number(tbl)
-end
+  end
   
-local function bit_xor(m, n)
+  function bit_xor(m, n)
     local tbl_m = to_bits(m)
     local tbl_n = to_bits(n)
     expand(tbl_m, tbl_n)
@@ -162,9 +170,9 @@ local function bit_xor(m, n)
     end
   
     return tbl2number(tbl)
-end
+  end
   
-local function bit_rshift(n, bits)
+  function bit_rshift(n, bits)
     check_int(n)
   
     local high_bit = 0
@@ -179,9 +187,9 @@ local function bit_rshift(n, bits)
       n = bit_or(floor(n), high_bit)
     end
     return floor(n)
-end
+  end
   
-local function bit_lshift(n, bits)
+  function bit_lshift(n, bits)
     check_int(n)
   
     if(n < 0) then
@@ -193,6 +201,7 @@ local function bit_lshift(n, bits)
       n = n*2
     end
     return bit_and(n, 4294967295) -- 0xFFFFFFFF
+  end
 end
 
 -- convert little-endian 32-bit int to a 4-char string