A-M baby

Task/Gray-code/D/gray-code-1.d

@@ -0,0 +1,23 @@
+import std.stdio;
+
+T enGray(T)(in T n) pure nothrow {
+    return n ^ (n >>> 1);
+}
+
+T deGray(T)(in T n) pure nothrow {
+    enum T MSB = (cast(T)1) << (T.sizeof * 8 - 1);
+
+    auto res = (n & MSB) ;
+    foreach (bit; 1 .. T.sizeof * 8)
+        res += (n ^ (res >>> 1)) & (MSB >>> bit);
+    return res;
+}
+
+void main() {
+    writeln("num  bits    encoded  decoded");
+    foreach (i; 0 .. 32) {
+        immutable encoded = enGray(i);
+        writefln("%2d: %5b ==> %5b : %2d",
+                 i, i, encoded, deGray(encoded));
+    }
+}