Tool to convert Gray code. Gray code, or reflected binary code, is a binary system which changes only one bit for each incrementation of one unity.

Gray Code - dCode

Tag(s) : Character Encoding, Electronics

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The **Gray code**, also called reflected binary, is a binary code having the property of modifying only one bit when a number is increased (or decreased) by one unit.

__Example:__

Number | Binary | Gray |
---|---|---|

0 | 0000 | 0000 |

1 | 0001 | 0001 |

2 | 0010 | 0011 |

3 | 0011 | 0010 |

4 | 0100 | 0110 |

5 | 0101 | 0111 |

6 | 0110 | 0101 |

7 | 0111 | 0100 |

8 | 1000 | 1100 |

This property can have several interesting practical applications, and the **gray code** appears in Baudot code, in Hanoi towers resolution, or position encoders.

To transform binary into reflected binary (**Gray code**), the algorithm consists in calculating the exclusive OR (XOR) between the binary value and itself but shifted by a row to the right (the last bit is deleted).

__Example:__ $$ \begin{align} 1 0 1 1 & \\ \oplus \rightarrow 1 0 1 & (1) \\ = 1 1 1 0 & \end{align} $$ The binary code 1011 has for value 1110 in its reflected version in **Gray code**.

The algorithm implementation in computers languages is done in one line and uses binary operators xor and shift: `function bin2gray(n) return n ^ (n >> 1)`

An algorithm for converting an integer to **Gray code** (binary) uses successive divisions by powers of 2 and looks at the parity of the rounded quotient. (Thanks G. Plousos)

__Example:__ $$ \begin{align} 29 / 2 = 14.5 \approx 15 & \Rightarrow 1 \\ 29 / 4 = 7.25 \approx 7 & \Rightarrow 1 \\ 29 / 8 = 3.625 \approx 4 & \Rightarrow 0 \\ 29 / 16 = 1.8125 \approx 2 & \Rightarrow 0 \\ 29 / 32 = 0.90625 \approx 1 & \Rightarrow 1 \end{align} $$ The decimal value 29 has the binary value 10011 in **Gray code**.

Another conversion method, more visual, is described by this image (Thanks G. Plousos) :

**Gray code** conversion can be done bit by bit. Given a number $ G = {g_0,g_1,\dots,g_n} $ with $ g_i $ each of its bits, then $ B = {b_0,b_1,\dots,b_n} $ is calculated as: $$ b_0 = g_0 \\ b_1 = g_0 \oplus g_1 \\ b_2 = g_0 \oplus g_1 \oplus g_2 \\ b_n = g_0 \oplus g_1 \oplus \dots \oplus g_n $$

In **gray code**, the most significant bit ($ g_0 $, often on the left) is always the same as the binary one ($ b_0 $).

The implementation of the conversion calculation also uses the xor and shift binary operators: `function gray2bin(n1) {`

n2 = n1;

while (n1 >>= 1) n2 ^= n1;

return n2;

}

**Gray Code** allow to count in binary but, to increment of one, only one bit changes. Here are the 16 first characters.

0000, 0001, 0011, 0010, 0110, 0111, 0101, 0100, 1100, 1101, 1111, 1110, 1010, 1011, 1001, 1000

The first equivalent decimal values are: 0, 1, 3, 2, 6, 7, 5, 4, 12, 13, 15, 14, 10, 11, 9, 8, 24, 25, 27, 26, 30, 31 , 29, 28, 20, 21, 23, 22, 18, 19, 17, 16, etc. here (link)

**Gray code** is modified only one bit at once when incrementing, with simplifies calculations and speed them up in some cases.

**Gray code** is modified only one bit at once when incrementing, with simplifies calculations and speed them up in some cases.

The color gray (also written *grey*) is a clue.

The **Gray code** is protected by a patent from 1953

dCode retains ownership of the online 'Gray Code' tool source code. Except explicit open source licence (indicated CC / Creative Commons / free), any 'Gray Code' algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any 'Gray Code' function (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and no data download, script, copy-paste, or API access for 'Gray Code' will be for free, same for offline use on PC, tablet, iPhone or Android ! dCode is free and online.

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- Code Gray Decoder
- Code Gray Encoder
- What is the gray code? (Definition)
- How to convert binary to Gray code?
- How to convert a decimal to Gray code?
- How to convert Gray code to binary?
- What are the first values in Gray Code?
- What are the advantages of Gray Code?
- how to recognize Gray Code?
- When Gray Code have been invented?

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