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));
+}

Task/Gray-code/PL-I/gray-code.pli

@@ -0,0 +1,31 @@
+(stringrange, stringsize):
+Gray_code: procedure options (main);  /* 15 November 2013 */
+   declare (bin(0:31), g(0:31), b2(0:31)) bit (5);
+   declare (c, carry) bit (1);
+   declare (i, j) fixed binary (7);
+
+   bin(0) = '00000'b;
+   do i = 0 to 31;
+      if i > 0 then
+         do;
+            carry = '1'b;
+            bin(i) = bin(i-1);
+            do j = 5 to 1 by -1;
+               c = substr(bin(i), j, 1) & carry;
+               substr(bin(i), j, 1) = substr(bin(i), j, 1) ^ carry;
+               carry = c;
+            end;
+         end;
+      g(i) = bin(i) ^ '0'b || substr(bin(i), 1, 4);
+   end;
+   do i = 0 to 31;
+      substr(b2(i), 1, 1) = substr(g(i), 1, 1);
+      do j = 2 to 5;
+         substr(b2(i), j, 1) = substr(g(i), j, 1) ^ substr(bin(i), j-1, 1);
+      end;
+   end;
+
+   do i = 0 to 31;
+      put skip edit (i, bin(i), g(i), b2(i)) (f(2), 3(x(1), b));
+   end;
+end Gray_code;

Task/Gray-code/Rust/gray-code.rust

@@ -0,0 +1,19 @@
+fn gray_encode(integer: uint) -> uint {
+	(integer >> 1) ^ integer
+}
+
+fn gray_decode(integer: uint) -> uint {
+	match integer {
+		0 => 0,
+		_ => integer ^ gray_decode(integer >> 1)
+	}
+}
+
+
+fn main() {
+	for i in range(0u,32u) {
+		println!("{:2} {:0>5t} {:0>5t} {:2}", i, i, gray_encode(i),
+			gray_decode(i));
+	}
+
+}