ltcode/dist/app/encode.js

Luby Transform Code implementation.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Encoder = void 0;
const utils_1 = require("./utils");
const prng_1 = require("./prng");
class Encoder {
    constructor(size = 100, seed) {
        this.seed = seed || this.randomSeed(1073741824);
        this.blockSize = size;
    }
    randomSeed(max) {
        const min = 0;
        const number = Math.random() * (max - min) + min;
        return Math.floor(number);
    }
    splitToBlocks(data) {
        const blocks = [];
        for (let i = 0; i < data.length; i += this.blockSize) {
            let block = data.subarray(i, i + this.blockSize);
            const n = (0, utils_1.intFromBytes)(block, "little");
            blocks.push(n);
        }
        return blocks;
    }
    generateEncodedBlock(data, blocks, prng) {
        const [blockseed, sampledBlocks] = prng.sample_source_blocks(null);
        let blockData = BigInt(0);
        for (const x of sampledBlocks) {
            blockData ^= blocks[x];
        }
        return JSON.stringify({
            length: data.length,
            size: this.blockSize,
            seed: blockseed,
            data: blockData.toString()
        });
    }
    *encode(data) {
        const blocks = this.splitToBlocks(new TextEncoder().encode(data));
        const prng = new prng_1.PRNG(blocks.length, this.seed);
        while (true) {
            yield this.generateEncodedBlock(data, blocks, prng);
        }
    }
}
exports.Encoder = Encoder;