node-djiparsetxt/dist/services/ScrambleTableService.js

command-line application that reads a DJI '.txt' file and outputs a json.

"use strict";
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    };
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.ScrambleTableService = void 0;
var BaseService_1 = __importDefault(require("./BaseService"));
var RecordTypes_1 = require("./RecordTypes");
var ScrambleTable_1 = require("./ScrambleTable");
var ScrambleTableService = /** @class */ (function (_super) {
    __extends(ScrambleTableService, _super);
    function ScrambleTableService() {
        var _this = _super !== null && _super.apply(this, arguments) || this;
        _this._scrambleTable = [];
        return _this;
    }
    Object.defineProperty(ScrambleTableService.prototype, "scrambleTable", {
        get: function () {
            if (this._scrambleTable.length === 0) {
                this._scrambleTable = ScrambleTable_1.scrambleTable;
            }
            return this._scrambleTable;
        },
        enumerable: false,
        configurable: true
    });
    ScrambleTableService.prototype.unscramble_record = function (record) {
        var data;
        if (record.type === RecordTypes_1.RecordTypes.JPEG) {
            data = record.data;
        }
        else {
            var uscrm = this.unscramble_buffer(record.data[0], record.type);
            if (uscrm == null) {
                data = record.data;
            }
            else {
                data = uscrm;
            }
        }
        return {
            type: record.type,
            length: record.length,
            data: data,
        };
    };
    ScrambleTableService.prototype.unscramble_buffer = function (buf, type) {
        var firstByte = buf.readUInt8(0);
        var scrambleKey = ((type - 1) << 8) | firstByte;
        var scrambleBytes = this.scrambleTable[scrambleKey];
        if (scrambleBytes === undefined) {
            return null;
        }
        var unscrambledBuf = Buffer.alloc(buf.length - 1);
        for (var writeOffset = 1; writeOffset < buf.length; writeOffset++) {
            var scrambleEntry = scrambleBytes[(writeOffset - 1) % 8];
            var val = buf.readUInt8(writeOffset) ^ scrambleEntry;
            unscrambledBuf.writeUInt8(val, writeOffset - 1);
        }
        return [unscrambledBuf];
    };
    return ScrambleTableService;
}(BaseService_1.default));
exports.ScrambleTableService = ScrambleTableService;
//# sourceMappingURL=ScrambleTableService.js.map