81 lines
1.9 KiB
JavaScript
81 lines
1.9 KiB
JavaScript
/**
|
|
* @author Imantas Lukenskas [imantas@lukenskas.dev]
|
|
* @copyright Imantas Lukenskas 2026
|
|
* @license Apache-2.0
|
|
*/
|
|
|
|
/**
|
|
* COBS-encode a byte array
|
|
* @param {Uint8Array} data
|
|
* @return {Uint8Array}
|
|
*/
|
|
export function toCobs(data) {
|
|
if (!data || data.length === 0) {
|
|
return new Uint8Array();
|
|
}
|
|
|
|
const output = [];
|
|
data = [0, ...data];
|
|
|
|
while (data.length > 0) {
|
|
const endIndex = data.findIndex((value, index) => value === 0 && index > 0);
|
|
|
|
if ((endIndex < 0 || endIndex > 254) && data.length > 254) {
|
|
output.push(255);
|
|
output.push(...data.slice(1, 255));
|
|
data = [...data.slice(255)];
|
|
if (data.length !== 0) {
|
|
data = [0, ...data];
|
|
}
|
|
} else if (endIndex < 0) {
|
|
output.push(data.length);
|
|
output.push(...data.slice(1));
|
|
data = [];
|
|
} else {
|
|
output.push(endIndex);
|
|
output.push(...data.slice(1, endIndex));
|
|
data = data.slice(endIndex);
|
|
}
|
|
}
|
|
|
|
return output;
|
|
}
|
|
|
|
/**
|
|
* COBS-decode a byte array
|
|
* @param {Uint8Array} data
|
|
* @return {Uint8Array}
|
|
*/
|
|
export function fromCobs(data) {
|
|
if (!data || data.length === 0) {
|
|
return new Uint8Array();
|
|
}
|
|
|
|
const output = [];
|
|
|
|
while (data.length > 0) {
|
|
if (data[0] === 0xFF) {
|
|
output.push(...data.slice(1, 255));
|
|
data = data.slice(255);
|
|
} else {
|
|
const nextZeroIndex = data[0];
|
|
output.push(...data.slice(1, nextZeroIndex));
|
|
data = data.slice(nextZeroIndex);
|
|
|
|
let blockSize = data[0];
|
|
while (data.length > 0) {
|
|
output.push(0, ...data.slice(1, blockSize));
|
|
data = data.slice(blockSize);
|
|
|
|
if (blockSize === 0xFF) {
|
|
break;
|
|
}
|
|
|
|
blockSize = data[0];
|
|
}
|
|
}
|
|
}
|
|
|
|
return output;
|
|
}
|