Support for ADFS 640K (.adl) disk image files (mattgodbolt#357)

* initial pass

* Reworked interval timing

Reworked interval timing to resolve an occasional hang after a BREAK.

* Correcting utils to prev version

Correcting utils to prev version

* Add or update the Azure App Service build and deployment workflow config

* Music 5000 support

* Add or update the Azure App Service build and deployment workflow config

* CD fix

* added M5000 master SSD

* updated README

* tidy-up #1

* tidyup #2

* tidyup #3

* Amendments from inital PR review

Removed .DS_Store
Put back discs/.gitignore
Image files renamed to lower case
Removed my intro text in README.md

* Improved audio worklet design pattern

Taken inspiration from another pending branch (which uses audio worklets for the main sound recorder).

* alignment of the 'fix' for the left/right channel swap

I had previously chosen to address this by swapping over the speaker channels at output, but now will align with what the Beebem devs did and re-map the stereo generator array instead

* Typo in stereo array ... oops

* Updates as part of Matt code review

* conversion of music 5000 / teletext functions to classes

+ replacement of tabs with 4 x spaces (yuk!) :) :)

* Support for ADFS (640K) disk images (.adl)

* Avoid repetition of the 16 : 10 logic with the addition of sectorsPerTrack

* Added ability to download the current drive 0 image

This allows any local changes made to disks to be persisted

* Largely cosmetic changes following a run by prettier

fdc.js

@@ -78,6 +78,7 @@ export function BaseDisc(fdc, name, data, flusher) {
     if (data === null || data === undefined) throw new Error("Bad disc data");
     let nameDetails = utils.discImageSize(name);
     let isDsd = nameDetails.isDsd;
+    let sectorsPerTrack = nameDetails.isDoubleDensity ? 16 : 10;
     let byteSize = nameDetails.byteSize;
     if (data.length > byteSize && !isDsd) {
         // For safety, if SSD is too big, assume it's a mis-named DSD.
@@ -90,6 +91,7 @@ export function BaseDisc(fdc, name, data, flusher) {
     this.fdc = fdc;
     this.name = name;
     this.isDsd = isDsd;
+    this.sectorsPerTrack = sectorsPerTrack;
     this.flusher = flusher;
     this.data = data;
     this.byteWithinSector = 0;
@@ -146,7 +148,7 @@ export function BaseDisc(fdc, name, data, flusher) {
             case 6:
                 this.fdc.discFinishRead();
                 this.rsector++;
-                if (this.rsector === 10) this.rsector = 0;
+                if (this.rsector === this.sectorsPerTrack) this.rsector = 0;
                 return;
         }
         this.byteWithinSector++;
@@ -161,7 +163,7 @@ export function BaseDisc(fdc, name, data, flusher) {
         if (++this.byteWithinSector === 256) {
             this.byteWithinSector = 0;
             this.sectorOffset += 256;
-            if (++this.formatSector === 10) {
+            if (++this.formatSector === this.sectorsPerTrack) {
                 this.fdc.discFinishRead();
                 this.flush();
                 return;
@@ -174,49 +176,49 @@ export function BaseDisc(fdc, name, data, flusher) {
         if (this.flusher) this.flusher();
     };
     BaseDisc.prototype.seek = (track) => {
-        this.seekOffset = track * 10 * 256;
+        this.seekOffset = track * this.sectorsPerTrack * 256;
         if (this.isDsd) this.seekOffset <<= 1;
         const oldTrack = this.track;
         this.track = track;
         return this.track - oldTrack;
     };
-    BaseDisc.prototype.check = (track, side, density) => {
-        if (this.track !== track || density || (side && !this.isDsd)) {
+    BaseDisc.prototype.check = (track, side) => {
+        if (this.track !== track || (side && !this.isDsd)) {
             this.notFoundTask.reschedule(500 * DiscTimeSlice);
             return false;
         }
         return true;
     };
-    BaseDisc.prototype.read = (sector, track, side, density) => {
-        if (!this.check(track, side, density)) return;
+    BaseDisc.prototype.read = (sector, track, side) => {
+        if (!this.check(track, side)) return;
         this.side = side;
         this.readTask.reschedule(DiscTimeSlice);
-        this.sectorOffset = sector * 256 + (side ? 10 * 256 : 0);
+        this.sectorOffset = sector * 256 + (side ? this.sectorsPerTrack * 256 : 0);
         this.byteWithinSector = 0;
     };
-    BaseDisc.prototype.write = (sector, track, side, density) => {
-        if (!this.check(track, side, density)) return;
+    BaseDisc.prototype.write = (sector, track, side) => {
+        if (!this.check(track, side)) return;
         this.side = side;
         // NB in old code this used to override "time" to be -1000, which immediately forced a write.
         // I'm not sure why that was required. So I'm ignoring it here. Any funny disc write bugs might be
         // traceable to this change.
         this.writeTask.reschedule(DiscTimeSlice);
-        this.sectorOffset = sector * 256 + (side ? 10 * 256 : 0);
+        this.sectorOffset = sector * 256 + (side ? this.sectorsPerTrack * 256 : 0);
         this.byteWithinSector = 0;
     };
-    BaseDisc.prototype.address = (track, side, density) => {
-        if (!this.check(track, side, density)) return;
+    BaseDisc.prototype.address = (track, side) => {
+        if (!this.check(track, side)) return;
         this.side = side;
         this.readAddrTask.reschedule(DiscTimeSlice);
         this.byteWithinSector = 0;
         this.rsector = 0;
     };
-    BaseDisc.prototype.format = (track, side, density) => {
-        if (!this.check(track, side, density)) return;
+    BaseDisc.prototype.format = (track, side) => {
+        if (!this.check(track, side)) return;
         this.side = side;
         this.formatTask.reschedule(DiscTimeSlice);
         this.formatSector = 0;
-        this.sectorOffset = side ? 10 * 256 : 0;
+        this.sectorOffset = side ? this.sectorsPerTrack * 256 : 0;
         this.byteWithinSector = 0;
     };
 }

index.html

@@ -78,6 +78,10 @@
                 <li class="if-drive-available">
                   <a href="#google-drive" class="dropdown-item" id="open-drive-link">From Google Drive</a>
                 </li>
+                <hr />
+                <li class="if-drive-available">
+                  <a href="#download-drive" class="dropdown-item" id="download-drive-link">Download drive 0 image</a>
+                </li>
               </ul>
             </li>
             <li class="nav-item dropdown embed-hide">
@@ -445,14 +449,14 @@ <h5 class="modal-title" id="discModalLabel">Load disc image</h5>
                 <a href="#"><span class="name"></span></a> - <span class="description"></span>
               </li>
             </ul>
-            To load a custom disc image, get an SSD or DSD file and load it below. Search the web, or check somewhere
-            like
+            To load a custom disc image, get an SSD, DSD or ADL file and load it below. Search the web, or check
+            somewhere like
             <a href="http://www.bbcmicrogames.com/GettingStarted.html">here</a> for these. Be aware the images are
             usually stored in a ZIP file, and you'll need to unzip first.
             <div class="disc">
               <label
-                >Load local SSD or DSD file:
-                <input type="file" id="disc_load" accept=".ssd,.dsd,application/binary" />
+                >Load local SSD, DSD or ADL file:
+                <input type="file" id="disc_load" accept=".ssd,.dsd,.adl,application/binary" />
               </label>
             </div>
           </div>

main.js

@@ -1103,6 +1103,19 @@ $("#google-drive form").on("submit", function (e) {
     );
 });
 
+$("#download-drive-link").on("click", function () {
+    var a = document.createElement("a");
+    document.body.appendChild(a);
+    a.style = "display: none";
+
+    var blob = new Blob([processor.fdc.drives[0].data], { type: "application/octet-stream" }),
+        url = window.URL.createObjectURL(blob);
+    a.href = url;
+    a.download = processor.fdc.drives[0].name;
+    a.click();
+    window.URL.revokeObjectURL(url);
+});
+
 $("#hard-reset").click(function (event) {
     processor.reset(true);
     event.preventDefault();

models.js

@@ -70,7 +70,7 @@ export const allModels = [
         false
     ),
     new Model(
-        "BBC B with Teletext",
+        "BBC B (with Teletext)",
         ["BTeletext"],
         ["os.rom", "BASIC.ROM", "b/DFS-0.9.rom", "ats-3.0.rom"],
         true,
@@ -81,7 +81,7 @@ export const allModels = [
         true
     ),
     new Model(
-        "BBC B with Music 5000",
+        "BBC B (with Music 5000)",
         ["BMusic5000"],
         ["os.rom", "BASIC.ROM", "b/DFS-0.9.rom", "ample.rom"],
         true,

utils.js

@@ -1025,6 +1025,7 @@ var knownDiscExtensions = {
     uef: true,
     ssd: true,
     dsd: true,
+    adl: true,
 };
 
 var knownRomExtensions = {
@@ -1078,13 +1079,21 @@ export function discImageSize(name) {
     // - 10 sectors per track.
     // - 256 bytes per sector.
     var isDsd = false;
+    var isDoubleDensity = false;
     var byteSize = 80 * 10 * 256;
     // DSD, aka. double-sided disc is twice the size.
     if (name.toLowerCase().endsWith(".dsd")) {
         byteSize *= 2;
         isDsd = true;
     }
-    return { isDsd: isDsd, byteSize: byteSize };
+    if (name.toLowerCase().endsWith(".adl")) {
+        // ADFS (Large) disks are:
+        // double density, double sided, 80 track, 16 sectors per track, 256 bytes per sector (640K)
+        byteSize = 2 * 80 * 16 * 256;
+        isDsd = true;
+        isDoubleDensity = true;
+    }
+    return { isDsd: isDsd, isDoubleDensity: isDoubleDensity, byteSize: byteSize };
 }
 
 export function setDiscName(data, name) {