@polkadot/util
Version:
A collection of useful utilities for @polkadot
31 lines (30 loc) • 1.52 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.hexFixLength = hexFixLength;
const addPrefix_js_1 = require("./addPrefix.js");
const stripPrefix_js_1 = require("./stripPrefix.js");
/**
* @name hexFixLength
* @summary Shifts a hex string to a specific bitLength
* @description
* Returns a `0x` prefixed string with the specified number of bits contained in the return value. (If bitLength is -1, length checking is not done). Values with more bits are trimmed to the specified length. Input values with less bits are returned as-is by default. When `withPadding` is set, shorter values are padded with `0`.
* @example
* <BR>
*
* ```javascript
* import { hexFixLength } from '@polkadot/util';
*
* console.log('fixed', hexFixLength('0x12', 16)); // => 0x12
* console.log('fixed', hexFixLength('0x12', 16, true)); // => 0x0012
* console.log('fixed', hexFixLength('0x0012', 8)); // => 0x12
* ```
*/
function hexFixLength(value, bitLength = -1, withPadding = false) {
const strLength = Math.ceil(bitLength / 4);
const hexLength = strLength + 2;
return (0, addPrefix_js_1.hexAddPrefix)((bitLength === -1 || value.length === hexLength || (!withPadding && value.length < hexLength))
? (0, stripPrefix_js_1.hexStripPrefix)(value)
: (value.length > hexLength)
? (0, stripPrefix_js_1.hexStripPrefix)(value).slice(-1 * strLength)
: `${'0'.repeat(strLength)}${(0, stripPrefix_js_1.hexStripPrefix)(value)}`.slice(-1 * strLength));
}