morse-pro-cw.js

/*!
This code is © Copyright Stephen C. Phillips, 2018.
Email: steve@scphillips.com
*/
/*
Licensed under the EUPL, Version 1.2 or – as soon they will be approved by the European Commission - subsequent versions of the EUPL (the "Licence");
You may not use this work except in compliance with the Licence.
You may obtain a copy of the Licence at: https://joinup.ec.europa.eu/community/eupl/
Unless required by applicable law or agreed to in writing, software distributed under the Licence is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the Licence for the specific language governing permissions and limitations under the Licence.
*/

import * as WPM from './morse-pro-wpm';
import MorseMessage from './morse-pro-message';

/**
 * Class to create the on/off timings needed by e.g. sound generators. Timings are in milliseconds; "off" timings are negative.
 *
 * @example
 * import MorseCW from 'morse-pro-cw';
 * var morseCW = new MorseCW();
 * morseCW.translate("abc");
 * var timings = morseCW.getTimings();
 */
export default class MorseCW extends MorseMessage {
    /**
     * @param {boolean} [prosigns=true] - whether or not to include prosigns in the translations
     * @param {number} [wpm=20] - the speed in words per minute using PARIS as the standard word
     * @param {number} [fwpm=wpm] - the Farnsworth speed in words per minute (defaults to wpm)
     */
    constructor(useProsigns = true, wpm = 20, fwpm = wpm) {
        super(useProsigns);
        /** @type {number} */
        this.wpm = wpm;
        /** @type {number} */
        this.fwpm = fwpm;
    }

    /** 
     * Set the WPM speed. Ensures that Farnsworth WPM is no faster than WPM.
     * @type {number} */
    set wpm(wpm) {
        this._wpm = wpm;
        if (wpm < this._fwpm) {
            this._fwpm = wpm;
        }
    }

    /** @type {number} */
    get wpm() {
        return this._wpm;
    }

    /**
     * Set the Farnsworth WPM speed. Ensures that WPM is no slower than Farnsworth WPM.
     *  @type {number} */
    set fwpm(fwpm) {
        this._fwpm = fwpm;
        if (fwpm > this._wpm) {
            this._wpm = fwpm;
        }
    }

    /** @type {number} */
    get fwpm() {
        return this._fwpm;
    }

    /** 
     * Get the length of the space between words in ms.
     * @type {number} */
    get wordSpace() {
        return WPM.wordSpace(this._wpm, this._fwpm);
    }

    /**
     * Return an array of millisecond timings.
     * With the Farnsworth method, the morse characters are played at one
     * speed and the spaces between characters at a slower speed.
     * @return {number[]}
     */
    getTimings() {
        return MorseCW.getTimingsGeneral(
            WPM.ditLength(this._wpm),
            WPM.dahLength(this._wpm),
            WPM.ditSpace(this._wpm),
            WPM.charSpace(this._wpm, this._fwpm),
            WPM.wordSpace(this._wpm, this._fwpm),
            this.morse
        );
    }

    /**
     * Return an array of millisecond timings.
     * Each sound and space has a duration. The durations of the spaces are distinguished by being negative.
     * @param {number} dit - the length of a dit in milliseconds
     * @param {number} dah - the length of a dah in milliseconds (normally 3 * dit)
     * @param {number} ditSpace - the length of an intra-character space in milliseconds (1 * dit)
     * @param {number} charSpace - the length of an inter-character space in milliseconds (normally 3 * dit)
     * @param {number} wordSpace - the length of an inter-word space in milliseconds (normally 7 * dit)
     * @param {string} morse - the (canonical) morse code string (matching [.-/ ]*)
     * @return {number[]}
     */
    static getTimingsGeneral(dit, dah, ditSpace, charSpace, wordSpace, morse) {
        //console.log("Morse: " + morse);
        morse = morse.replace(/ \/ /g, '/');  // this means that a space is only used for inter-character
        morse = morse.replace(/([\.\-])(?=[\.\-])/g, "$1+");  // put a + in between all dits and dahs
        var times = [];
        for (var i = 0; i < morse.length; i++) {
            switch (morse[i]) {
                case '.':
                    times.push(dit);
                    break;
                case '-':
                    times.push(dah);
                    break;
                case '+':
                    times.push(-ditSpace);
                    break;
                case " ":
                    times.push(-charSpace);
                    break;
                case "/":
                    times.push(-wordSpace);
                    break;
            }
        }
        //console.log("Timings: " + times);
        return times;
    }

    /**
     * Get the total duration of the message in ms
     8 @return {number}
     */
    getDuration() {
        var times = this.getTimings();
        var t = 0;
        for (var i = 0; i < times.length; i++) {
            t += Math.abs(times[i]);
        }
        return t;
    }
}