Data commit

Task/Gray-code/Cowgol/gray-code.cowgol

@@ -0,0 +1,45 @@
+include "cowgol.coh";
+
+sub gray_encode(n: uint8): (r: uint8) is
+    r := n ^ n >> 1;
+end sub;
+
+sub gray_decode(n: uint8): (r: uint8) is
+    r := n;
+    while n > 0 loop
+        n := n >> 1;
+        r := r ^ n;
+    end loop;
+end sub;
+
+sub print_binary(n: uint8) is
+    var buf: uint8[9];
+    var ptr := &buf[8];
+    [ptr] := 0;
+    loop
+        ptr := @prev ptr;
+        [ptr] := (n & 1) + '0';
+        n := n >> 1;
+        if n == 0 then break; end if;
+    end loop;
+    print(ptr);
+end sub;
+
+sub print_row(n: uint8) is
+    print_i8(n);
+    print(":\t");
+    print_binary(n);
+    print("\t=>\t");
+    var gray_code := gray_encode(n);
+    print_binary(gray_code);
+    print("\t=>\t");
+    var decoded := gray_decode(gray_code);
+    print_i8(decoded);
+    print_nl();
+end sub;
+
+var i: uint8 := 0;
+while i <= 31 loop
+    print_row(i);
+    i := i + 1;
+end loop;