A-M baby

Task/Gray-code/Tcl/gray-code-1.tcl

@@ -0,0 +1,14 @@
+namespace eval gray {
+    proc encode n {
+	expr {$n ^ $n >> 1}
+    }
+    proc decode n {
+	# Compute some bit at least as large as MSB
+	set i [expr {2**int(ceil(log($n+1)/log(2)))}]
+	set b [set bprev [expr {$n & $i}]]
+	while {[set i [expr {$i >> 1}]]} {
+	    set b [expr {$b | [set bprev [expr {$n & $i ^ $bprev >> 1}]]}]
+	}
+	return $b
+    }
+}