Subversion Repositories aysalia

; 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