Add an out-of-memory error dialog to shell

shell.asm

@@ -8,6 +8,8 @@ struc window
 	.y resw 1
 	.data resw 1
 	.icon resb 1
+	.visible resb 1
+	.resizable resb 1
 	.mouse_released_inside resb 1
 	.status resb 1
 	.res_x resw 1
@@ -17,6 +19,7 @@ endstruc
 
 WINDOW_ID_ICON equ 0
 WINDOW_ID_FILE_WINDOW equ 1
+WINDOW_ID_OOM_ERROR equ 2
 
 WINDOW_MOVE equ 1
 WINDOW_RESIZE equ 2
@@ -58,16 +61,16 @@ initialize:
 	call set_wallpaper
 
 	; Create icon for the disk on the desktop
-	mov ax, cs
-	add ax, WINDOW_ID_ICON
-	xchg [es:GLOBAL_WINDOW_CHAIN_HEAD], ax
-	mov [windows + WINDOW_ID_ICON*window.size + window.next], ax
 	mov word [windows + WINDOW_ID_ICON*window.size + window.width], 5
 	mov word [windows + WINDOW_ID_ICON*window.size + window.height], 3
 	mov word [windows + WINDOW_ID_ICON*window.size + window.x], 1
 	mov word [windows + WINDOW_ID_ICON*window.size + window.y], 1
 	mov word [windows + WINDOW_ID_ICON*window.size + window.data], disk_icon
 	mov byte [windows + WINDOW_ID_ICON*window.size + window.icon], 1
+	mov ax, cs
+	add ax, WINDOW_ID_ICON
+	mov si, windows + WINDOW_ID_ICON*window.size
+	call show_window
 
 	; Initialize file window but don't show it
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.width], 40
@@ -75,8 +78,14 @@ initialize:
 	mov word [windows + WINDOW_ID_FILE_WINDOW*window.size + window.x], 10
 	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.icon], 0
-	mov byte [windows + WINDOW_ID_FILE_WINDOW*window.size + window.mouse_released_inside], 0
+	mov byte [windows + WINDOW_ID_FILE_WINDOW*window.size + window.resizable], 1
+
+	; Initialize error dialogs
+	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.width], 13
+	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.height], 2
+	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.x], 30
+	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.y], 10
+	mov word [windows + WINDOW_ID_OOM_ERROR*window.size + window.data], oom_error_dialog
 
 	call request_redraw
 
@@ -300,19 +309,30 @@ click:
 	cmp byte [si + window.icon], 0
 	je .file_window
 	.icon:
-		call show_file_window
+		mov ax, cs
+		add ax, WINDOW_ID_FILE_WINDOW
+		mov si, windows + WINDOW_ID_FILE_WINDOW*window.size
+		call show_window
+		call render_file_window
 		jmp .end
 
 	.file_window:
 		call raise_window
 
+		; Save window ID
+		mov bp, ax
+
 		cmp bx, [si + window.y]
 		jne .not_title_bar
 
-		; If clicked the window close button
+		; Resize button
 		mov ax, [si + window.x]
+		cmp byte [si + window.resizable], 0
+		je .not_resizable
 		cmp ax, cx
 		je .resize
+		.not_resizable:
+		; Window close button
 		add ax, [si + window.width]
 		dec ax
 		cmp ax, cx
@@ -332,7 +352,7 @@ click:
 			jmp .end
 
 		.close:
-			call hide_file_window
+			call hide_window
 			jmp .end
 		
 		
@@ -495,43 +515,6 @@ move:
 	pop dx
 	ret
 
-show_file_window:
-	cmp byte [file_window_visible], 0
-	jne .already_visible
-
-	push ax
-
-	mov ax, PONYDOS_SEG
-	mov es, ax
-
-	mov ax, cs
-	add ax, WINDOW_ID_FILE_WINDOW
-	xchg [es:GLOBAL_WINDOW_CHAIN_HEAD], ax
-	mov si, windows + WINDOW_ID_FILE_WINDOW*window.size
-	mov [si + window.next], ax
-
-	; Populate file window contents
-	call render_file_window
-
-	pop ax
-
-	mov byte [file_window_visible], 1
-
-	call request_redraw
-
-	.already_visible:
-	ret
-
-hide_file_window:
-	mov cx, cs
-	add cx, WINDOW_ID_FILE_WINDOW
-	call unhook_window
-
-	mov byte [file_window_visible], 0
-
-	call request_redraw
-	ret
-
 ; out:
 ;  clobbers everything
 launch:
@@ -591,7 +574,11 @@ launch:
 		jz .found_free_segment
 		inc si
 		loop .find_free_segment
-	; TODO: Display an alert on OOM error
+	; Display an error dialog if we can't allocate a segment
+	mov ax, cs
+	add ax, WINDOW_ID_OOM_ERROR
+	mov si, windows + WINDOW_ID_OOM_ERROR*window.size
+	call show_window
 	pop cx
 	pop ax
 	jmp .end
@@ -673,7 +660,7 @@ forward_event:
 ; in:
 ;  bx = valid window id for this process
 ; out:
-;  si = pointer to window's data block
+;  si = pointer to window structure
 get_window:
 	push bx
 
@@ -693,6 +680,62 @@ get_window:
 	pop bx
 	ret
 
+; in:
+;  ax = window ID
+;  si = pointer to window structure
+show_window:
+	push ax
+
+	cmp byte [si + window.visible], 0
+	je .not_yet_visible
+	call raise_window
+	jmp .end
+
+	.not_yet_visible:
+	call hook_window
+	mov [si + window.next], ax
+
+	mov byte [si + window.visible], 1
+
+	call request_redraw
+
+	.end:
+	pop ax
+	ret
+
+; in:
+;  bp = window ID
+;  si = pointer to window structure
+hide_window:
+	push cx
+
+	mov cx, bp
+	call unhook_window
+
+	mov byte [windows + WINDOW_ID_FILE_WINDOW*window.size + window.visible], 0
+
+	call request_redraw
+
+	pop cx
+	ret
+
+; in:
+;  ax = window ID to hook
+; out:
+;  ax = next window ID
+hook_window:
+	push bp
+	push es
+
+	mov bp, PONYDOS_SEG
+	mov es, bp
+
+	xchg [es:GLOBAL_WINDOW_CHAIN_HEAD], ax
+
+	pop es
+	pop bp
+	ret
+
 ; in:
 ;  cx = window ID to unhook
 unhook_window:
@@ -1025,9 +1068,16 @@ disk_icon:
 	db 0x00, 0x0f, 0x00, 0x0f, 0x09, 0x0f, 0x00, 0x0f, 0x00, 0x0f
 	db 0x00, 0x0f, 0x00, 0x0f, '|', 0x0f, 0x00, 0x0f, 0x00, 0x0f
 
+oom_error_dialog:
+	db 'E', 0x0f, 'r', 0x0f, 'r', 0x0f, 'o', 0x0f, 'r', 0x0f
+	times 13-5-1 db 0x00, 0x0f
+	db 'x', 0x0f
+	db 'O', 0xf0, 'u', 0xf0, 't', 0xf0, ' ', 0xf0, 'o', 0xf0, 'f', 0xf0, ' ', 0xf0, 'm', 0xf0, 'e', 0xf0, 'm', 0xf0, 'o', 0xf0, 'r', 0xf0, 'y', 0xf0
+
 windows:
 	times window.size db 0
 	times window.size db 0
+	times window.size db 0
 
 launch_filename times FS_DIRENT_NAME_SIZE db 0