Data commit

Task/Gray-code/Lua/gray-code-1.lua

@@ -0,0 +1,18 @@
+local _M = {}
+
+local bit  = require('bit')
+local math = require('math')
+
+_M.encode = function(number)
+  return bit.bxor(number, bit.rshift(number, 1));
+end
+
+_M.decode = function(gray_code)
+  local value = 0
+  while gray_code > 0 do
+    gray_code, value = bit.rshift(gray_code, 1), bit.bxor(gray_code, value)
+  end
+  return value
+end
+
+return _M

Task/Gray-code/Lua/gray-code-2.lua

@@ -0,0 +1,24 @@
+local bit = require 'bit'
+local gray = require 'gray'
+
+-- simple binary string formatter
+local function to_bit_string(n, width)
+  width = width or 1
+  local output = ""
+  while n > 0 do
+    output = bit.band(n,1) .. output
+    n = bit.rshift(n,1)
+  end
+  while #output < width do
+    output = '0' .. output
+  end
+  return output
+end
+
+for i = 0,31 do
+  g = gray.encode(i);
+  gd = gray.decode(g);
+  print(string.format("%2d : %s => %s => %s : %2d", i,
+    to_bit_string(i,5), to_bit_string(g, 5),
+    to_bit_string(gd,5), gd))
+end