Introduce a way to return to text mode. Clean up the handling of

mode transitions.

1 files changed, 65 insertions, 52 deletions

diff --git a/ldlinux.asm b/ldlinux.asm
index d8c717c9..78329f8b 100644
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -2940,25 +2940,7 @@ dir_success:
 		mov bx,ax
 		or bx,dx		; Sets ZF iff DX:AX is zero
 dir_return:
-		ret
-
-;
-; adjust_screen: Set the internal variables associated with the screen size.
-;		This is a subroutine in case we're loading a custom font.
-;
-adjust_screen:
-                mov al,[BIOS_vidrows]
-                and al,al
-                jnz vidrows_is_ok
-                mov al,24                       ; No vidrows in BIOS, assume 25
-						; (Remember: vidrows == rows-1)
-vidrows_is_ok:  mov [VidRows],al
-                mov ah,0fh
-                int 10h                         ; Read video state
-                mov [TextPage],bh
-                dec ah                          ; Store count-1 (same as rows)
-                mov [VidCols],ah
-bf_ret:		ret
+lf_ret:		ret
 
 ;
 ; loadfont:	Load a .psf font file and install it onto the VGA console
@@ -2972,43 +2954,42 @@ loadfont:
 
 		mov ax,[trackbuf]		; Magic number
 		cmp ax,0436h
-		jne bf_ret
+		jne lf_ret
 
 		mov al,[trackbuf+2]		; File mode
 		cmp al,5			; Font modes 0-5 supported
-		ja bf_ret
+		ja lf_ret
 
 		mov bh,byte [trackbuf+3]	; Height of font
 		cmp bh,2			; VGA minimum
-		jb bf_ret
+		jb lf_ret
 		cmp bh,32			; VGA maximum
-		ja bf_ret
+		ja lf_ret
 
 		; Copy to font buffer
 		mov si,trackbuf+4		; Start of font data
 		mov [VGAFontSize],bh
 		mov di,vgafontbuf
-		mov bp,di			; Address of font data for INT 10h
 		mov cx,(32*256) >> 2		; Maximum size
 		rep movsd
 
-		xor bl,bl			; Needed by both INT 10h calls
-		cmp [UsingVGA], byte 1		; Are we in graphics mode?
-		je .graphics
-
-		mov cx,256
-		xor dx,dx
-		mov ax,1110h
-		int 10h				; Load into VGA RAM
+		; Fall through to use_font
 
-		xor bl,bl
-		mov ax,1103h			; Select page 0
-		int 10h
+;
+; use_font:
+; 	This routine activates whatever font happens to be in the
+;	vgafontbuf, and updates the adjust_screen data.
+;
+use_font:
+		mov bp,vgafontbuf
+		mov bh,[VGAFontSize]
 
-		jmp short adjust_screen
+		xor bl,bl			; Needed by both INT 10h calls
+		cmp [UsingVGA], byte 1		; Are we in graphics mode?
+		jne .text
 
 .graphics:
-		; CX = 0 on entry
+		xor cx,bx
 		mov cl,bh			; CX = bytes/character
 		mov ax,480
 		div cl				; Compute char rows per screen
@@ -3017,9 +2998,40 @@ loadfont:
 		mov [VidRows],al
 		mov ax,1121h			; Set user character table
 		int 10h
-		; VidCols = 80, TextPage = 0 set by graphics mode select
+		mov [VidRows], byte 79		; Always 80 bytes/line
+		mov [TextPage], byte 0		; Always page 0
 		ret	; No need to call adjust_screen
 
+.text:
+		mov cx,256
+		xor dx,dx
+		mov ax,1110h
+		int 10h				; Load into VGA RAM
+
+		xor bl,bl
+		mov ax,1103h			; Select page 0
+		int 10h
+
+		; Fall through to adjust_screen
+
+;
+; adjust_screen: Set the internal variables associated with the screen size.
+;		This is a subroutine in case we're loading a custom font.
+;
+adjust_screen:
+                mov al,[BIOS_vidrows]
+                and al,al
+                jnz vidrows_is_ok
+                mov al,24                       ; No vidrows in BIOS, assume 25
+						; (Remember: vidrows == rows-1)
+vidrows_is_ok:  mov [VidRows],al
+                mov ah,0fh
+                int 10h                         ; Read video state
+                mov [TextPage],bh
+                dec ah                          ; Store count-1 (same as rows)
+                mov [VidCols],ah
+		ret
+
 ;
 ; loadkeys:	Load a LILO-style keymap; SI and DX:AX set by searchdir
 ;
@@ -3097,6 +3109,8 @@ msg_putchar:                                    ; Normal character
                 je msg_newline
                 cmp al,0Ch                      ; <FF> = clear screen
                 je msg_formfeed
+		cmp al,19h			; <EM> = return to text mode
+		je near msg_novga
 		cmp al,18h			; <CAN> = VGA filename follows
 		je near msg_vga
 		jnb .not_modectl
@@ -3200,6 +3214,10 @@ msg_setvgafileptr:
 		mov [VGAFilePtr],di
 msg_ret:	ret
 
+msg_novga:
+		call vgaclearmode
+		jmp short msg_initvars
+
 msg_viewimage:
 		push es
 		push ds
@@ -4085,19 +4103,7 @@ vgasetmode:
 		int 10h
 		mov [UsingVGA], byte 1
 
-		mov [VidCols], byte 79	; Always 80 chars/screen
-		mov [TextPage], byte 0	; Always page 0
-
-		mov cx,[VGAFontSize]
-		mov ax,480
-		div cl
-		mov dl,al
-		dec al			; VidRows is stored -1
-		mov [VidRows],al
-		mov bp,vgafontbuf
-		xor bx,bx
-		mov ax,1121h		; Set graphics font
-		int 10h
+		call use_font		; Set graphics font/data
 		mov byte [ScrollAttribute], 00h
 
 		xor ax,ax		; Set ZF
@@ -4109,17 +4115,24 @@ vgasetmode:
 ;	Disable VGA graphics.  It is not safe to assume any value for DS.
 ;
 vgaclearmode:
+		push ds
+		push cs
+		pop ds			; DS <- CS
 		pushad
-		cmp [cs:UsingVGA], byte 1
+		cmp [UsingVGA], byte 1
 		jne .done
 		mov ax,0003h		; Return to normal video mode
 		int 10h
 ;		mov dx,TextColorReg	; Restore color registers
 ;		mov ax,1002h
 ;		int 10h
+
+
+		call use_font		; Restore text font/data
 		mov byte [ScrollAttribute], 07h
 .done:
 		popad
+		pop ds
 		ret
 
 ;