/
equals.ts
44 lines (41 loc) · 1.42 KB
/
equals.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/** Check whether binary arrays are equal to each other using 8-bit comparisons.
* @private
* @param a first array to check equality
* @param b second array to check equality
*/
function equalsNaive(a: Uint8Array, b: Uint8Array): boolean {
for (let i = 0; i < b.length; i++) {
if (a[i] !== b[i]) return false;
}
return true;
}
/** Check whether binary arrays are equal to each other using 32-bit comparisons.
* @private
* @param a first array to check equality
* @param b second array to check equality
*/
function equals32Bit(a: Uint8Array, b: Uint8Array): boolean {
const len = a.length;
const compressible = Math.floor(len / 4);
const compressedA = new Uint32Array(a.buffer, 0, compressible);
const compressedB = new Uint32Array(b.buffer, 0, compressible);
for (let i = compressible * 4; i < len; i++) {
if (a[i] !== b[i]) return false;
}
for (let i = 0; i < compressedA.length; i++) {
if (compressedA[i] !== compressedB[i]) return false;
}
return true;
}
/** Check whether binary arrays are equal to each other.
* @param a first array to check equality
* @param b second array to check equality
*/
export function equals(a: Uint8Array, b: Uint8Array): boolean {
if (a.length !== b.length) {
return false;
}
return a.length < 1000 ? equalsNaive(a, b) : equals32Bit(a, b);
}