; Aysalia DOS Launcher
; Launches aydos1.gam and aydos2.gam
; Revision 2018-12-07
; (C) 2018 Daniel Marschall, ViaThinkSoft
.model small
.stack 100h
; -------------------------------------------------------
.data
exename1 db "AYDOS1.GAM", 0
exename2 db "AYDOS2.GAM", 0
cmdargs db 0, '', 0Dh
dummy_fcb db 36 dup(0)
paramblk dw 0 ; use environment of parent
dw cmdargs ; command line arguments
dw 0 ; cmdargs_seg
dw dummy_fcb ; fcb1
dw 0 ; fcb1_seg
dw dummy_fcb ; fcb2
dw 0 ; fcb2_seg
menu1 db 13, 10, \
13, 10, \
13, 10, \
13, 10, \
' Aysalia DOS', 13, 10, \
13, 10, \
13, 10, \
' Welches Spiel soll gestartet werden?', 13, 10, \
13, 10, \
' Dr', 81h, 'cke eine der folgenden Tasten:', 13, 10, \
13, 10, \
' 1 Aysalia DOS I', 13, 10, \
' 2 Aysalia DOS II', 13, 10, \
13, 10, \
' 9 Beenden', 13, 10, \
13, 10, \
13, 10, \
13, 10, 0
error1 db 13, 10, \
'Fehler: Spiel kann nicht gestartet werden. Fehlt eine Datei?', 13, 10, \
13, 10, 0
gameover1 db 13, 10, \
'Spiel zu Ende!', 13, 10, \
13, 10, 0
; -------------------------------------------------------
.code
clear_vga PROC
mov ax, 0A000h
mov es, ax
xor di, di
mov ax, 0
mov cx, 64000
rep stosb
ret
clear_vga ENDP
set_screen12 PROC
mov ah, 0 ; set screen mode
mov al, 12h ; graphic mode, 640x480 pixel, 16 colors (VGA)
int 10h
ret
set_screen12 ENDP
setup_paramblk PROC
mov ax, cs
mov [paramblk + 4], ax ; cmdargs_seg
mov [paramblk + 8], ax ; fcb1_seg
mov [paramblk + 12], ax ; fcb2_seg
ret
setup_paramblk ENDP
set_numlock_on PROC
push es
; In Windows 98+, we cannot access the BIOS Data Area,
; so we use this technique to check if we are inside Windows.
; This code was taken from http://www.fysnet.net/chkwin.htm
xor ax,ax ; point es:di to 0000:0000h
mov es,ax ;
mov di,ax ;
mov ax,1602h ; Get API entry point
int 2Fh ; call to multiplex interrupt
mov ax,es ;
or ax,ax ; if es:di doesn't point to 0000:0000h
jnz short is_win ; then Windows is running a DOS box
or di,di ; else
jnz short is_win ; we are in True DOS
; Now the actual code that sets numlock on
push ds
mov ax, 40h
mov ds, ax ; Go to BIOS Data Area ( http://stanislavs.org/helppc/bios_data_area.html )
mov bx, 17h ; Load Keyboard flag byte 0
mov al, [bx] ; Read
or al, 20h ; Set bit 5 (numlock) to 1
mov [bx], al ; Write
pop ds
is_win:
pop es
ret
set_numlock_on ENDP
flush_keyb_buf PROC
mov ah, 0Ch ; Flush input buffer and input
mov al, 0
int 21h
ret
flush_keyb_buf ENDP
exit_to_dos PROC
mov ah, 4Ch
mov al, 00h
int 21h
ret
exit_to_dos ENDP
sleep_5 PROC
mov ah, 00h
int 1Ah
cmp dx, 7FFFh
jg sleep_5_upperhalf
sleep_5_lowerhalf:
mov bx, dx
add bx, 91 ; 18.2 = 1 sec (therefore 91 = 5 sec)
sleep_5_lowerhalf_again:
int 1Ah
cmp dx, bx
jl sleep_5_lowerhalf_again
ret
sleep_5_upperhalf:
mov bx, dx
sub bx, 7FFFh
add bx, 91 ; 18.2 = 1 sec (therefore 91 = 5 sec)
sleep_5_upperhalf_again:
int 1Ah
sub dx, 7FFFh
cmp dx, bx
jl sleep_5_upperhalf_again
ret
sleep_5 ENDP
print_color_string PROC
; This function requires:
; dx = Pointer to zero terminated string
; cl = Color
mov ah, 0Eh
print_color_string_again:
mov bx, dx
mov al, [bx]
test al, al ; is the character zero? then we are done
jz print_color_string_end
mov bl, cl
int 10h
add dx, 1 ; go to next character
jmp print_color_string_again
print_color_string_end:
ret
print_color_string ENDP
set_bg_color PROC
; This function requires:
; bl = Color
mov ah, 0Bh
mov bh, 00h
int 10h
ret
set_bg_color ENDP
print_menu_screen PROC
; Clear screen
call clear_vga
; Set background color
mov bl, 8 ; dark green background
call set_bg_color
; Set text color
mov cl, 0Fh ; white font
lea dx, menu1
call print_color_string
ret
print_menu_screen ENDP
print_error_screen PROC
; Clear screen
call clear_vga
; Set background color
mov bl, 4 ; dark red background
call set_bg_color
; Set text color
mov cl, 0Fh ; white font
lea dx, error1
call print_color_string
ret
print_error_screen ENDP
print_gameover_message PROC
; Keep cursor position
; Set background color
mov bl, 4 ; dark red background
call set_bg_color
; Set text color
mov cl, 0Fh ; white font
lea dx, gameover1
call print_color_string
ret
print_gameover_message ENDP
; -------------------------------------------------------
start:
; Setup data segment
mov ax, @data ; moving base address of data to ax
mov ds, ax ; moving contents of ax into ds
; data section now gets initialized
; Preserve the original screen mode
mov ah, 0Fh ; Query screen mode
int 10h
push ax ; actually, we are only interested in register al (screen mode), not in ah (column count)
; Change numlock to ON
; DOSBox has a bug where the NumLock is not correctly set to the setting of the host system,
; so you have to press the NumLock key twice so that DOSBox recognizes the status.
; see: https://sourceforge.net/p/dosbox/bugs/71/
; https://superuser.com/questions/255102/is-there-a-way-to-use-the-numeric-keypad-in-dosbox/1146986
; Since the game uses number keys very often, we set NumLock to ON
call set_numlock_on
; Reduce size of own application to give the called applications more space
; see https://stackoverflow.com/a/10067627
mov ah, 4Ah
mov bx, 100 ; 100 paragraphs a 16 bytes = 1600 bytes
int 21h
menu:
; Video Mode VGA 12
call set_screen12
; Flush keyboard buffer
call flush_keyb_buf
; Print menu screen
call print_menu_screen
retry:
; Query keyboard input
mov ah, 07h ; Direct character input, without echo
int 21h
cmp al, '1'
je prog1
cmp al, '2'
je prog2
cmp al, '9'
je exit
; Invalid input
jmp retry
prog1:
; Clear screen
call clear_vga
; Setup parameter block for the EXEC command
call setup_paramblk
; Start game 1
mov ax, @data ; ds:dx = ASCIZ program name (must include extension)
mov ds, ax
lea dx, exename1
mov ax, @data ; es:bx = Parameter block
mov es, ax
mov bx, paramblk
mov ah, 4Bh ; execute
mov al, 00h ; load and execute
int 21h ; DOS API
; Is everything OK? Or is the GAM file missing?
jc error
; Notify the player that the game has finished
jmp gameover
prog2:
; Clear screen
call clear_vga
; Setup parameter block for the EXEC command
call setup_paramblk
; Start game 2
mov ax, @data ; ds:dx = ASCIZ program name (must include extension)
mov ds, ax
lea dx, exename2
mov ax, @data ; es:bx = Parameter block
mov es, ax
mov bx, paramblk
mov ah, 4Bh ; execute
mov al, 00h ; load and execute
int 21h ; DOS API
; Is everything OK? Or is the GAM file missing?
jc error
; Notify the player that the game has finished
jmp gameover
error:
; Video Mode VGA 12
call set_screen12
; Print error
call print_error_screen
; Give the player time to read the error message (approx 5 seconds)
call sleep_5
; Go back to the menu
jmp menu
gameover:
; Print gameover message
call print_gameover_message
; Give the player time to read the game over message (approx 5 seconds)
call sleep_5
; Go back to the menu
jmp menu
exit:
; Reset video mode to DOS default
pop ax ; the video mode we have preserved at program start
mov ah, 0 ; set screen mode
int 10h
; Return to DOS
call exit_to_dos
; -------------------------------------------------------
end start