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