coap/dist/lib/block.js

A CoAP library for node modelled after 'http'

"use strict";
/*
 * Copyright (c) 2013-2021 node-coap contributors.
 *
 * node-coap is licensed under an MIT +no-false-attribs license.
 * All rights not explicitly granted in the MIT license are reserved.
 * See the included LICENSE file for more details.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.generateBlockOption = generateBlockOption;
exports.parseBlockOption = parseBlockOption;
exports.exponentToByteSize = exponentToByteSize;
exports.byteSizeToExponent = byteSizeToExponent;
const TwoPowTwenty = 1048575;
/**
 *
 * @param numOrBlockState The block sequence number or a block state object.
 * @param more Can indicate if more blocks are to follow.
 * @param size The block size.
 */
function generateBlockOption(numOrBlockState, more, size) {
    let num;
    if (typeof numOrBlockState === 'object') {
        num = numOrBlockState.num;
        more = numOrBlockState.more;
        size = numOrBlockState.size;
    }
    else {
        num = numOrBlockState;
    }
    if (num == null || more == null || size == null) {
        throw new Error('Invalid parameters');
    }
    if (num > TwoPowTwenty) {
        throw new Error('Sequence number out of range');
    }
    let buff = Buffer.alloc(4);
    const value = (num << 4) | (more << 3) | (size & 7);
    buff.writeInt32BE(value);
    if (num >= 4096) {
        buff = buff.slice(1, 4);
    }
    else if (num >= 16) {
        buff = buff.slice(2, 4);
    }
    else {
        buff = buff.slice(3, 4);
    }
    return buff;
}
function parseBlockOption(buff) {
    if (buff.length === 1) {
        buff = Buffer.concat([Buffer.alloc(3), buff]);
    }
    else if (buff.length === 2) {
        buff = Buffer.concat([Buffer.alloc(2), buff]);
    }
    else if (buff.length === 3) {
        buff = Buffer.concat([Buffer.alloc(1), buff]);
    }
    else {
        throw new Error(`Invalid block option buffer length. Must be 1, 2 or 3. It is ${buff.length}`);
    }
    const value = buff.readInt32BE();
    const num = (value >> 4) & TwoPowTwenty;
    const more = (value & 8) === 8 ? 1 : 0;
    const size = value & 7;
    return {
        num,
        more,
        size
    };
}
function exponentToByteSize(expo) {
    return Math.pow(2, expo + 4);
}
function byteSizeToExponent(byteSize) {
    return Math.round(Math.log(byteSize) / Math.log(2) - 4);
}
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