DeskTop: Preserve all 14 devices in ProDOS DEVLST table. Fixes #549

A buffer for preserving DEVCNT+DEVLST was too short. To support the maximum number of devices and the count, 15 bytes are needed. On restoration, this would cause the first entry in the next table to appear as a ProDOS device, e.g. Slot 0, Drive 1.
a2stuff · Aug 29, 2021 · 551d0b0 · 551d0b0 · c0mmander8 · Sep 2, 2021
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Showing 5 changed files with 14 additions and 9 deletions.
diff --git a/desktop/init.s b/desktop/init.s
@@ -201,9 +201,9 @@ end:
 
 .scope
         ;; Make a copy of the original device list
-        ldx     DEVCNT
-        inx
-:       lda     DEVLST-1,x
+        ldx     DEVCNT          ; number of devices
+        inx                     ; include DEVCNT itself
+:       lda     DEVLST-1,x      ; DEVCNT is at DEVLST-1
         sta     devlst_backup,x
         dex
         bpl     :-
@@ -905,8 +905,7 @@ cvi_result:
         dex
 :       inx
         copy    DEVLST+1,x, DEVLST,x
-        lda     device_to_icon_map+1,x
-        sta     device_to_icon_map,x
+        copy    device_to_icon_map+1,x, device_to_icon_map,x
         cpx     DEVCNT
         bne     :-
         dec     DEVCNT

diff --git a/desktop/internal.inc b/desktop/internal.inc
@@ -29,9 +29,13 @@ kDAFileAuxType  = $641           ; High bit set = don't show in Apple menu
 
 kMaxDeskAccCount        = 12
 
+;;; Maximum number of ProDOS devices (2 per slot 1-7). This is the
+;;; maximum size of DEVLST not counting DEVCNT itself.
+kMaxDevListSize = 14
+
 ;;; Maximum number of volumes displayed/tracked. This is two per slot,
 ;;; except S3,D2 is assumed to be /RAM which is disconnected.
-kMaxVolumes     = 13
+kMaxVolumes     = kMaxDevListSize - 1
 
 ;;; ============================================================
 ;;; Window/Icon Metrics

diff --git a/desktop/main.s b/desktop/main.s
@@ -1184,8 +1184,8 @@ filerecords_free_start:
 
 .proc restore_device_list
         ldx     devlst_backup
-        inx
-:       copy    devlst_backup,x, DEVLST-1,x
+        inx                     ; include the count itself
+:       copy    devlst_backup,x, DEVLST-1,x ; DEVCNT is at DEVLST-1
         dex
         bpl     :-
         rts

diff --git a/desktop/res.s b/desktop/res.s
@@ -938,7 +938,7 @@ entries_read_this_block:
 
 ;;; Backup copy of DEVLST made before detaching ramdisk
 devlst_backup:
-        .res    kMaxVolumes+1, 0 ; TODO: Why +1?
+        .res    kMaxDevListSize+1, 0 ; +1 for DEVCNT itself
 
         ;; index is device number (in DEVLST), value is icon number
 device_to_icon_map:

diff --git a/res/notes/testplan.txt b/res/notes/testplan.txt
@@ -300,3 +300,5 @@
 * Launch DeskTop. Select a folder. File > Open. Verify that the folder icon is no longer selected.
 * Launch DeskTop. Double-click a folder. Verify that the volume icon is no longer selected.
 * Launch DeskTop. Open a window containing a folder. Position the window so that the folder icon will not be obscured when opened. Select the folder. File > Open. Verify that the folder is no longer selected.
+
+* Configure a system with 14 devices. Launch and then exit DeskTop. Load another ProDOS app that enumerates devices. Verify that all expected devices are present, and that there's no "Slot 0, Drive 1" entry.