September 2017 Update

Task/Gray-code/Bc/gray-code.bc

@@ -0,0 +1,46 @@
+scale = 0  /* to use integer division */
+
+/* encode Gray code */
+define e(i) {
+	auto h, r
+
+	if (i <= 0) return 0
+	h = i / 2
+	r = e(h) * 2                /* recurse */
+	if (h % 2 != i % 2) r += 1  /* xor low bits of h, i */
+	return r
+}
+
+/* decode Gray code */
+define d(i) {
+	auto h, r
+
+	if (i <= 0) return 0
+	h = d(i / 2)                /* recurse */
+	r = h * 2
+	if (h % 2 != i % 2) r += 1  /* xor low bits of h, i */
+	return r
+}
+
+
+/* print i as 5 binary digits */
+define p(i) {
+	auto d, d[]
+
+	for (d = 0; d <= 4; d++) {
+		d[d] = i % 2
+		i /= 2
+	}
+	for (d = 4; d >= 0; d--) {
+		if(d[d] == 0) "0"
+		if(d[d] == 1) "1"
+	}
+}
+
+for (i = 0; i < 32; i++) {
+	/* original */ t = p(i); " => "
+	/* encoded */ e = e(i); t = p(e); " => "
+	/* decoded */ d = d(e); t = p(d); "
+"
+}
+quit

Task/Gray-code/Crystal/gray-code-1.crystal

@@ -0,0 +1,12 @@
+def gray_encode(bin)
+  bin ^ (bin >> 1)
+end
+
+def gray_decode(gray)
+  bin = gray
+  while gray > 0
+    gray >>= 1
+    bin ^= gray
+  end
+  bin
+end

Task/Gray-code/Crystal/gray-code-2.crystal

@@ -0,0 +1,5 @@
+(0..31).each do |n|
+  gr = gray_encode n
+  bin = gray_decode gr
+  printf "%2d : %05b => %05b => %05b : %2d\n", n, n, gr, bin, bin
+end

Task/Gray-code/D/gray-code-2.d

@@ -17,7 +17,7 @@ T[][] grayDict(int N, T)() pure nothrow {
     T[][] dict = [gray!(N, T)(), [0]];
     // Append inversed gray encoding mapping.
     foreach (immutable i; 1 .. dict[0].length)
-        dict[1] ~= countUntil(dict[0], i);
+        dict[1] ~= cast(T)countUntil(dict[0], i);
     return dict;
 }
 

Task/Gray-code/FreeBASIC/gray-code.freebasic

@@ -0,0 +1,41 @@
+' version 18-01-2017
+' compile with: fbc -s console
+
+Function gray2bin(g As UInteger) As UInteger
+
+    Dim As UInteger b = g
+
+    While g
+        g Shr= 1
+        b Xor= g
+    Wend
+
+    Return b
+
+End Function
+
+Function bin2gray(b As UInteger) As UInteger
+
+    Return b Xor (b Shr 1)
+
+End Function
+
+' ------=< MAIN >=------
+
+Dim As UInteger i
+
+Print " i     binary     gray   gra2bin"
+Print String(32,"=")
+
+For i = 0 To 31
+    Print Using "## --> "; i;
+    print Bin(i,5); " --> ";
+    Print Bin(bin2gray(i),5); " --> ";
+    Print Bin(gray2bin(bin2gray(i)),5)
+Next
+
+' empty keyboard buffer
+While Inkey <> "" : Wend
+Print : Print "hit any key to end program"
+Sleep
+End

Task/Gray-code/Kotlin/gray-code.kotlin

@@ -0,0 +1,24 @@
+// version 1.0.6
+
+object Gray {
+    fun encode(n: Int) = n xor (n shr 1)
+
+    fun decode(n: Int): Int {
+        var p  = n
+        var nn = n
+        while (nn != 0) {
+            nn = nn shr 1
+            p = p xor nn
+        }
+        return p
+    }
+}
+
+fun main(args: Array<String>) {
+    println("Number\tBinary\tGray\tDecoded")
+    for (i in 0..31) {
+        print("$i\t${Integer.toBinaryString(i)}\t")
+        val g = Gray.encode(i)
+        println("${Integer.toBinaryString(g)}\t${Gray.decode(g)}")
+    }
+}

Task/Gray-code/PHP/gray-code-1.php

@@ -1,28 +0,0 @@
-<?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/PHP/gray-code-2.php

@@ -1,31 +0,0 @@
-(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/Sidef/gray-code.sidef

@@ -1,14 +1,14 @@
 func bin2gray(n) {
-    n ^ (n >> 1);
+    n ^ (n >> 1)
 }
 
 func gray2bin(num) {
-    var bin = num;
-    while (num >>= 1) { bin ^= num };
-    return bin;
+    var bin = num
+    while (num >>= 1) { bin ^= num }
+    return bin
 }
 
-0..31 -> each { |i|
-    var gr = bin2gray(i);
-    printf("%d\t%b\t%b\t%b\n", i, i, gr, gray2bin(gr));
-}
+{ |i|
+    var gr = bin2gray(i)
+    printf("%d\t%b\t%b\t%b\n", i, i, gr, gray2bin(gr))
+} << ^32

Task/Gray-code/Zkl/gray-code-1.zkl

@@ -0,0 +1,2 @@
+fcn grayEncode(n){ n.bitXor(n.shiftRight(1)) }
+fcn grayDecode(g){ b:=g; while(g/=2){ b=b.bitXor(g) } b }

Task/Gray-code/Zkl/gray-code-2.zkl

@@ -0,0 +1,4 @@
+foreach n in ([0..31]){
+   g:=grayEncode(n); b:=grayDecode(g);
+   println("%2d(%05.2B) --> %2d(%05.2B) --> %2d(%05.2B)".fmt(n,n,g,g,b,b));
+}