March 2014 update

Task/Gray-code/PHP/gray-code.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @author Elad Yosifon
+ */
+
+/**
+ * @param int $binary
+ * @return int
+ */
+function gray_encode($binary){
+	return $binary ^ ($binary >> 1);
+}
+
+/**
+ * @param int $gray
+ * @return int
+ */
+function gray_decode($gray){
+	$binary = $gray;
+	while($gray >>= 1) $binary ^= $gray;
+	return $binary;
+}
+
+for($i=0;$i<32;$i++){
+	$gray_encoded = gray_encode($i);
+	printf("%2d : %05b => %05b => %05b : %2d \n",$i, $i, $gray_encoded, $gray_encoded, gray_decode($gray_encoded));
+}