Skip to main content

Module iota::hex

HEX (Base16) encoding utility.

use std::vector;

Constants​

const EInvalidHexLength: u64 = 0;
const ENotValidHexCharacter: u64 = 1;

Vector of Base16 values from 00 to FF

const HEX: vector<vector<u8>> = vector[vector[48, 48], vector[48, 49], vector[48, 50], vector[48, 51], vector[48, 52], vector[48, 53], vector[48, 54], vector[48, 55], vector[48, 56], vector[48, 57], vector[48, 97], vector[48, 98], vector[48, 99], vector[48, 100], vector[48, 101], vector[48, 102], vector[49, 48], vector[49, 49], vector[49, 50], vector[49, 51], vector[49, 52], vector[49, 53], vector[49, 54], vector[49, 55], vector[49, 56], vector[49, 57], vector[49, 97], vector[49, 98], vector[49, 99], vector[49, 100], vector[49, 101], vector[49, 102], vector[50, 48], vector[50, 49], vector[50, 50], vector[50, 51], vector[50, 52], vector[50, 53], vector[50, 54], vector[50, 55], vector[50, 56], vector[50, 57], vector[50, 97], vector[50, 98], vector[50, 99], vector[50, 100], vector[50, 101], vector[50, 102], vector[51, 48], vector[51, 49], vector[51, 50], vector[51, 51], vector[51, 52], vector[51, 53], vector[51, 54], vector[51, 55], vector[51, 56], vector[51, 57], vector[51, 97], vector[51, 98], vector[51, 99], vector[51, 100], vector[51, 101], vector[51, 102], vector[52, 48], vector[52, 49], vector[52, 50], vector[52, 51], vector[52, 52], vector[52, 53], vector[52, 54], vector[52, 55], vector[52, 56], vector[52, 57], vector[52, 97], vector[52, 98], vector[52, 99], vector[52, 100], vector[52, 101], vector[52, 102], vector[53, 48], vector[53, 49], vector[53, 50], vector[53, 51], vector[53, 52], vector[53, 53], vector[53, 54], vector[53, 55], vector[53, 56], vector[53, 57], vector[53, 97], vector[53, 98], vector[53, 99], vector[53, 100], vector[53, 101], vector[53, 102], vector[54, 48], vector[54, 49], vector[54, 50], vector[54, 51], vector[54, 52], vector[54, 53], vector[54, 54], vector[54, 55], vector[54, 56], vector[54, 57], vector[54, 97], vector[54, 98], vector[54, 99], vector[54, 100], vector[54, 101], vector[54, 102], vector[55, 48], vector[55, 49], vector[55, 50], vector[55, 51], vector[55, 52], vector[55, 53], vector[55, 54], vector[55, 55], vector[55, 56], vector[55, 57], vector[55, 97], vector[55, 98], vector[55, 99], vector[55, 100], vector[55, 101], vector[55, 102], vector[56, 48], vector[56, 49], vector[56, 50], vector[56, 51], vector[56, 52], vector[56, 53], vector[56, 54], vector[56, 55], vector[56, 56], vector[56, 57], vector[56, 97], vector[56, 98], vector[56, 99], vector[56, 100], vector[56, 101], vector[56, 102], vector[57, 48], vector[57, 49], vector[57, 50], vector[57, 51], vector[57, 52], vector[57, 53], vector[57, 54], vector[57, 55], vector[57, 56], vector[57, 57], vector[57, 97], vector[57, 98], vector[57, 99], vector[57, 100], vector[57, 101], vector[57, 102], vector[97, 48], vector[97, 49], vector[97, 50], vector[97, 51], vector[97, 52], vector[97, 53], vector[97, 54], vector[97, 55], vector[97, 56], vector[97, 57], vector[97, 97], vector[97, 98], vector[97, 99], vector[97, 100], vector[97, 101], vector[97, 102], vector[98, 48], vector[98, 49], vector[98, 50], vector[98, 51], vector[98, 52], vector[98, 53], vector[98, 54], vector[98, 55], vector[98, 56], vector[98, 57], vector[98, 97], vector[98, 98], vector[98, 99], vector[98, 100], vector[98, 101], vector[98, 102], vector[99, 48], vector[99, 49], vector[99, 50], vector[99, 51], vector[99, 52], vector[99, 53], vector[99, 54], vector[99, 55], vector[99, 56], vector[99, 57], vector[99, 97], vector[99, 98], vector[99, 99], vector[99, 100], vector[99, 101], vector[99, 102], vector[100, 48], vector[100, 49], vector[100, 50], vector[100, 51], vector[100, 52], vector[100, 53], vector[100, 54], vector[100, 55], vector[100, 56], vector[100, 57], vector[100, 97], vector[100, 98], vector[100, 99], vector[100, 100], vector[100, 101], vector[100, 102], vector[101, 48], vector[101, 49], vector[101, 50], vector[101, 51], vector[101, 52], vector[101, 53], vector[101, 54], vector[101, 55], vector[101, 56], vector[101, 57], vector[101, 97], vector[101, 98], vector[101, 99], vector[101, 100], vector[101, 101], vector[101, 102], vector[102, 48], vector[102, 49], vector[102, 50], vector[102, 51], vector[102, 52], vector[102, 53], vector[102, 54], vector[102, 55], vector[102, 56], vector[102, 57], vector[102, 97], vector[102, 98], vector[102, 99], vector[102, 100], vector[102, 101], vector[102, 102]];

Function encode​

Encode bytes in lowercase hex

public fun encode(bytes: vector<u8>): vector<u8>
Implementation
public fun encode(bytes: vector<u8>): vector<u8> {
let (mut i, mut r, l) = (0, vector[], bytes.length());
let hex_vector = HEX;
while (i < l) {
r.append(hex_vector[bytes[i] as u64]);
i = i + 1;
};
r
}

Function decode​

Decode hex into bytes Takes a hex string (no 0x prefix) (e.g. b"0f3a") Returns vector of bytes that represents the hex string (e.g. x"0f3a") Hex string can be case insensitive (e.g. b"0F3A" and b"0f3a" both return x"0f3a") Aborts if the hex string does not have an even number of characters (as each hex character is 2 characters long) Aborts if the hex string contains non-valid hex characters (valid characters are 0 - 9, a - f, A - F)

public fun decode(hex: vector<u8>): vector<u8>
Implementation
public fun decode(hex: vector<u8>): vector<u8> {
let (mut i, mut r, l) = (0, vector[], hex.length());
assert!(l % 2 == 0, EInvalidHexLength);
while (i < l) {
let decimal = decode_byte(hex[i]) * 16 + decode_byte(hex[i + 1]);
r.push_back(decimal);
i = i + 2;
};
r
}

Function decode_byte​

fun decode_byte(hex: u8): u8
Implementation
fun decode_byte(hex: u8): u8 {
if (/* 0 .. 9 / 48 <= hex && hex < 58) {
hex - 48
} else if (/ A .. F / 65 <= hex && hex < 71) {
10 + hex - 65
} else if (/ a .. f */ 97 <= hex && hex < 103) {
10 + hex - 97
} else {
abort ENotValidHexCharacter
}
}