Files
start-sdk/lib/esm/deps/deno.land/std@0.140.0/bytes/equals.js
2023-02-27 10:38:56 -07:00

48 lines
1.5 KiB
JavaScript

// Copyright 2018-2022 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
*/
export function equalsNaive(a, b) {
if (a.length !== b.length)
return false;
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
*/
export function equalsSimd(a, b) {
if (a.length !== b.length)
return false;
const len = a.length;
const compressable = Math.floor(len / 4);
const compressedA = new Uint32Array(a.buffer, 0, compressable);
const compressedB = new Uint32Array(b.buffer, 0, compressable);
for (let i = compressable * 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, b) {
if (a.length < 1000)
return equalsNaive(a, b);
return equalsSimd(a, b);
}