C
int gray_encode(int n) {
return n ^ (n >> 1);
}
int gray_decode(int n) {
int p = n;
while (n >>= 1) p ^= n;
return p;
}
例：
#include <stdio.h>
/* Simple bool formatter, only good on range 0..31 */
void fmtbool(int n, char *buf) {
char *b = buf + 5;
*b=0;
do {
*--b = '0' + (n & 1);
n >>= 1;
} while (b != buf);
}
int main(int argc, char **argv) {
int i,g,b;
char bi[6],bg[6],bb[6];
for (i=0 ; i<32 ; i++) {
g = gray_encode(i);
b = gray_decode(g);
fmtbool(i,bi); fmtbool(g,bg); fmtbool(b,bb);
printf("%2d : %5s => %5s => %5s : %2d\n", i, bi, bg, bb, b);
}
return 0;
}
出力：
0 : 00000 => 00000 => 00000 : 0
1 : 00001 => 00001 => 00001 : 1
2 : 00010 => 00011 => 00010 : 2
3 : 00011 => 00010 => 00011 : 3
4 : 00100 => 00110 => 00100 : 4
5 : 00101 => 00111 => 00101 : 5
6 : 00110 => 00101 => 00110 : 6
7 : 00111 => 00100 => 00111 : 7
8 : 01000 => 01100 => 01000 : 8
9 : 01001 => 01101 => 01001 : 9
10 : 01010 => 01111 => 01010 : 10
11 : 01011 => 01110 => 01011 : 11
12 : 01100 => 01010 => 01100 : 12
13 : 01101 => 01011 => 01101 : 13
14 : 01110 => 01001 => 01110 : 14
15 : 01111 => 01000 => 01111 : 15
16 : 10000 => 11000 => 10000 : 16
17 : 10001 => 11001 => 10001 : 17
18 : 10010 => 11011 => 10010 : 18
19 : 10011 => 11010 => 10011 : 19
20 : 10100 => 11110 => 10100 : 20
21 : 10101 => 11111 => 10101 : 21
22 : 10110 => 11101 => 10110 : 22
23 : 10111 => 11100 => 10111 : 23
24 : 11000 => 10100 => 11000 : 24
25 : 11001 => 10101 => 11001 : 25
26 : 11010 => 10111 => 11010 : 26
27 : 11011 => 10110 => 11011 : 27
28 : 11100 => 10010 => 11100 : 28
29 : 11101 => 10011 => 11101 : 29
30 : 11110 => 10001 => 11110 : 30
31 : 11111 => 10000 => 11111 : 31
C ++
#include <bitset>
#include <iostream>
#include <string>
#include <assert.h>
uint32_t gray_encode(uint32_t b)
{
return b ^ (b >> 1);
}
uint32_t gray_decode(uint32_t g)
{
for (uint32_t bit = 1U << 31; bit > 1; bit >>= 1)
{
if (g & bit) g ^= bit >> 1;
}
return g;
}
std::string to_binary(int value) // utility function
{
const std::bitset<32> bs(value);
const std::string str(bs.to_string());
const size_t pos(str.find('1'));
return pos == std::string::npos ? "0" : str.substr(pos);
}
int main()
{
std::cout << "Number\tBinary\tGray\tDecoded\n";
for (uint32_t n = 0; n < 32; ++n)
{
uint32_t g = gray_encode(n);
assert(gray_decode(g) == n);
std::cout << n << "\t" << to_binary(n) << "\t" << to_binary(g) << "\t" << g << "\n";
}
}
出力：
Number Binary Gray Decoded
0 0 0 0
1 1 1 1
2 10 11 3
3 11 10 2
4 100 110 6
5 101 111 7
6 110 101 5
7 111 100 4
8 1000 1100 12
9 1001 1101 13
10 1010 1111 15
11 1011 1110 14
12 1100 1010 10
13 1101 1011 11
14 1110 1001 9
15 1111 1000 8
16 10000 11000 24
17 10001 11001 25
18 10010 11011 27
19 10011 11010 26
20 10100 11110 30
21 10101 11111 31
22 10110 11101 29
23 10111 11100 28
24 11000 10100 20
25 11001 10101 21
26 11010 10111 23
27 11011 10110 22
28 11100 10010 18
29 11101 10011 19
30 11110 10001 17
31 11111 10000 16
C＃の
using System;
public class Gray {
public static ulong grayEncode(ulong n) {
return n^(n>>1);
}
public static ulong grayDecode(ulong n) {
ulong i=1<<8*64-2; //long is 64-bit
ulong p, b=p=n&i;
while((i>>=1)>0)
b|=p=n&i^p>>1;
return b;
}
public static void Main(string[] args) {
Console.WriteLine("Number\tBinary\tGray\tDecoded");
for(ulong i=0;i<32;i++) {
Console.WriteLine(string.Format("{0}\t{1}\t{2}\t{3}", i, Convert.ToString((long)i, 2), Convert.ToString((long)grayEncode(i), 2), grayDecode(grayEncode(i))));
}
}
}
ゴー
package main
import "fmt"
func enc(b int) int {
return b ^ b>>1
}
func dec(g int) (b int) {
for ; g != 0; g >>= 1 {
b ^= g
}
return
}
func main() {
fmt.Println("decimal binary gray decoded")
for b := 0; b < 32; b++ {
g := enc(b)
d := dec(g)
fmt.Printf(" %2d %05b %05b %05b %2d\n", b, b, g, d, d)
}
}
ジャワ
public class Gray {
public static long grayEncode(long n){
return n ^ (n >>> 1);
}
public static long grayDecode(long n) {
long p = n;
while ((n >>>= 1) != 0)
p ^= n;
return p;
}
public static void main(String[] args){
System.out.println("i\tBinary\tGray\tDecoded");
for(int i = -1; i < 32;i++){
System.out.print(i +"\t");
System.out.print(Integer.toBinaryString(i) + "\t");
System.out.print(Long.toBinaryString(grayEncode(i))+ "\t");
System.out.println(grayDecode(grayEncode(i)));
}
}
}
Kotlin
// 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)}")
}
}
PHP
<?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));
}
パイソン
int型<>ビン変換
>>> def int2bin(n):
'From positive integer to list of binary bits, msb at index 0'
if n:
bits = []
while n:
n,remainder = divmod(n, 2)
bits.insert(0, remainder)
return bits
else: return [0]
>>> def bin2int(bits):
'From binary bits, msb at index 0 to integer'
i = 0
for bit in bits:
i = i * 2 + bit
return i
ビン<>グレー変換：
>>> def bin2gray(bits):
return bits[:1] + [i ^ ishift for i, ishift in zip(bits[:-1], bits[1:])]
>>> def gray2bin(bits):
b = [bits[0]]
for nextb in bits[1:]: b.append(b[-1] ^ nextb)
return b
ルビー
class Integer
# Converts a normal integer to a Gray code.
def to_gray
raise Math::DomainError, "integer is negative" if self < 0
self ^ (self >> 1)
end
# Converts a Gray code to a normal integer.
def from_gray
raise Math::DomainError, "integer is negative" if self < 0
recurse = proc do |i|
next 0 if i == 0
o = recurse[i >> 1] << 1
o | (i[0] ^ o[1])
end
recurse[self]
end
end
(0..31).each do |number|
encoded = number.to_gray
decoded = encoded.from_gray
printf "%2d : %5b => %5b => %5b : %2d\n",
number, number, encoded, decoded, decoded
end
