From f1ee23251e246d4aa665ecc332c7f3b0b4b78f6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juhani=20Krekel=C3=A4?= <juhani@krekelä.fi>
Date: Mon, 27 Mar 2023 14:45:39 +0300
Subject: [PATCH] Allow shell to be launched for another file window

---
 README.md |  1 -
 shell.asm | 62 +++++++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 53 insertions(+), 10 deletions(-)

diff --git a/README.md b/README.md
index 2f69887..346843b 100644
--- a/README.md
+++ b/README.md
@@ -69,5 +69,4 @@ installation option, for your safety.
 
 ### Nice to have
 
-* more file listing windows
 * ponysay
diff --git a/shell.asm b/shell.asm
index 0c3fc93..15e8500 100644
--- a/shell.asm
+++ b/shell.asm
@@ -48,16 +48,11 @@ initialize:
 	; Has shell been started already?
 	mov bp, PONYDOS_SEG
 	mov es, bp
+	xor bp, bp
 	cmp word [es:GLOBAL_WINDOW_CHAIN_HEAD], 0
 	je .not_relaunch
-	.relaunch:
-		; TODO: Display an alert if trying to re-run shell
-		; Clean up memory when exiting
-		mov bx, cs
-		mov cl, 12
-		shr bx, cl
-		mov byte [es:GLOBAL_MEMORY_ALLOCATION_MAP + bx], 0
-		jmp .end
+		mov bp, 1
+		jmp .skip_desktop
 	.not_relaunch:
 
 	; Set wallpaper
@@ -75,6 +70,7 @@ initialize:
 	mov si, windows + WINDOW_ID_ICON*window.size
 	call show_window
 
+	.skip_desktop:
 	; Initialize file window but don't show it
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.width], 40
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.height], 17
@@ -82,6 +78,17 @@ initialize:
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.y], 4
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.data], file_window
 	mov byte [windows + WINDOW_ID_FILE_WINDOW*window.size + window.resizable], 1
+	test bp, bp
+	jz .no_file_window_on_start
+	.file_window_on_start:
+		; Offset the window so that it's clearly another window
+		mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.x], 7
+		mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.y], 3
+		mov ax, cs
+		add ax, WINDOW_ID_FILE_WINDOW
+		mov si, windows + WINDOW_ID_FILE_WINDOW*window.size
+		call show_window
+	.no_file_window_on_start:
 
 	; Initialize error dialogs
 	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.width], 13
@@ -146,6 +153,11 @@ process_event:
 	.not_remove:
 
 	.end:
+	cmp byte [open_windows], 0
+	jne .windows_open
+	call deallocate_own_memory
+	.windows_open:
+
 	pop es
 	pop ds
 	pop bp
@@ -731,6 +743,8 @@ show_window:
 
 	call request_redraw
 
+	inc byte [open_windows]
+
 	.end:
 	pop ax
 	ret
@@ -744,10 +758,12 @@ hide_window:
 	mov cx, bp
 	call unhook_window
 
-	mov byte [windows + WINDOW_ID_FILE_WINDOW*window.size + window.visible], 0
+	mov byte [si + window.visible], 0
 
 	call request_redraw
 
+	dec byte [open_windows]
+
 	pop cx
 	ret
 
@@ -792,6 +808,7 @@ unhook_window:
 ; in:
 ;  ax = window ID to raise
 raise_window:
+	push ax
 	push bx
 	push cx
 	push si
@@ -819,6 +836,7 @@ raise_window:
 	pop si
 	pop cx
 	pop bx
+	pop ax
 	ret
 
 ; ------------------------------------------------------------------
@@ -1034,6 +1052,30 @@ copy_dirents:
 	pop cx
 	ret
 
+; ------------------------------------------------------------------
+; Memory management
+; ------------------------------------------------------------------
+
+deallocate_own_memory:
+	push bx
+	push cx
+	push es
+
+	mov bx, PONYDOS_SEG
+	mov es, bx
+
+	; Segment 0xn000 corresponds to slot n in the allocation table
+	mov bx, cs
+	mov cl, 12
+	shr bx, cl
+
+	mov byte [es:GLOBAL_MEMORY_ALLOCATION_MAP + bx], 0
+
+	pop es
+	pop cx
+	pop bx
+	ret
+
 ; ------------------------------------------------------------------
 ; String routines
 ; ------------------------------------------------------------------
@@ -1127,6 +1169,8 @@ windows:
 	times window.size db 0
 	times window.size db 0
 
+open_windows db 0
+
 launch_filename times FS_DIRENT_NAME_SIZE db 0
 
 section .bss