Data commit

Task/Gray-code/BCPL/gray-code.bcpl

@@ -0,0 +1,22 @@
+get "libhdr"
+
+let grayEncode(n) = n neqv (n >> 1)
+
+let grayDecode(n) = grayDecodeStep(0, n)
+and grayDecodeStep(r, n) =
+    n = 0 -> r,
+    grayDecodeStep(r neqv n, n >> 1)
+
+let binfmt(n) =
+    n = 0 -> 0,
+    (n & 1) + 10 * binfmt(n >> 1)
+
+let printRow(n) be
+$(  let enc = grayEncode(n)
+    let dec = grayDecode(enc)
+    writef("%I2: %I5 => %I5 => %I5 => %I2*N",
+           n, binfmt(n), binfmt(enc), binfmt(dec), dec)
+$)
+
+let start() be
+    for i = 0 to 31 do printRow(i)