69 lines
2.6 KiB
JavaScript
69 lines
2.6 KiB
JavaScript
/*---------------------------------------------------------------------------------------------
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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import { Lazy } from './lazy.js';
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const hasBuffer = (typeof Buffer !== 'undefined');
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const indexOfTable = new Lazy(() => new Uint8Array(256));
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let textDecoder;
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export class VSBuffer {
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/**
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* When running in a nodejs context, if `actual` is not a nodejs Buffer, the backing store for
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* the returned `VSBuffer` instance might use a nodejs Buffer allocated from node's Buffer pool,
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* which is not transferrable.
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*/
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static wrap(actual) {
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if (hasBuffer && !(Buffer.isBuffer(actual))) {
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// https://nodejs.org/dist/latest-v10.x/docs/api/buffer.html#buffer_class_method_buffer_from_arraybuffer_byteoffset_length
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// Create a zero-copy Buffer wrapper around the ArrayBuffer pointed to by the Uint8Array
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actual = Buffer.from(actual.buffer, actual.byteOffset, actual.byteLength);
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}
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return new VSBuffer(actual);
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}
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constructor(buffer) {
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this.buffer = buffer;
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this.byteLength = this.buffer.byteLength;
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}
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toString() {
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if (hasBuffer) {
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return this.buffer.toString();
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}
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else {
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if (!textDecoder) {
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textDecoder = new TextDecoder();
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}
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return textDecoder.decode(this.buffer);
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}
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}
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}
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export function readUInt16LE(source, offset) {
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return (((source[offset + 0] << 0) >>> 0) |
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((source[offset + 1] << 8) >>> 0));
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}
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export function writeUInt16LE(destination, value, offset) {
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destination[offset + 0] = (value & 0b11111111);
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value = value >>> 8;
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destination[offset + 1] = (value & 0b11111111);
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}
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export function readUInt32BE(source, offset) {
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return (source[offset] * Math.pow(2, 24)
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+ source[offset + 1] * Math.pow(2, 16)
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+ source[offset + 2] * Math.pow(2, 8)
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+ source[offset + 3]);
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}
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export function writeUInt32BE(destination, value, offset) {
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destination[offset + 3] = value;
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value = value >>> 8;
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destination[offset + 2] = value;
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value = value >>> 8;
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destination[offset + 1] = value;
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value = value >>> 8;
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destination[offset] = value;
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}
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export function readUInt8(source, offset) {
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return source[offset];
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}
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export function writeUInt8(destination, value, offset) {
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destination[offset] = value;
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}
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