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// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
/** Find first index of binary pattern from a. If not found, then return -1 **/
export function bytesFindIndex(a: Uint8Array, pat: Uint8Array): number {
const s = pat[0];
for (let i = 0; i < a.length; i++) {
if (a[i] !== s) continue;
const pin = i;
let matched = 1;
while (matched < pat.length) {
i++;
if (a[i] !== pat[i - pin]) {
break;
}
matched++;
}
if (matched === pat.length) {
return pin;
}
}
return -1;
}
/** Find last index of binary pattern from a. If not found, then return -1 **/
export function bytesFindLastIndex(a: Uint8Array, pat: Uint8Array) {
const e = pat[pat.length - 1];
for (let i = a.length - 1; i >= 0; i--) {
if (a[i] !== e) continue;
const pin = i;
let matched = 1;
while (matched < pat.length) {
i--;
if (a[i] !== pat[pat.length - 1 - (pin - i)]) {
break;
}
matched++;
}
if (matched === pat.length) {
return pin - pat.length + 1;
}
}
return -1;
}
/** Check whether binary arrays are equal to each other **/
export function bytesEqual(a: Uint8Array, match: Uint8Array): boolean {
if (a.length !== match.length) return false;
for (let i = 0; i < match.length; i++) {
if (a[i] !== match[i]) return false;
}
return true;
}
/** Check whether binary array has binary prefix **/
export function bytesHasPrefix(a: Uint8Array, prefix: Uint8Array): boolean {
for (let i = 0, max = prefix.length; i < max; i++) {
if (a[i] !== prefix[i]) return false;
}
return true;
}
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