Category : A Collection of Games for DOS and Windows
Archive   : KAOSHIDE.ZIP
Filename : KAOSHIDE.ASM

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ ÛÛ
;ÛÛ Hidden Kaos v1.0 ÛÛ
;ÛÛ ÛÛ
;ÛÛ Copyright (C) 1990 Philip Maland All Rights Reserved ÛÛ
;ÛÛ ÛÛ
;ÛÛ Created: June 3, 1990 ÛÛ
;ÛÛ ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ


Seg_a Segment
Assume cs:Seg_A, ds:Seg_A


org 100h

Start:
jmp Install ; Go to installation routine

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ Int 09h - New Handler ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

Int_09:
push ax ; Save the world
push bx
push cx
push dx
push es
pushf

in al,60h ; Get scan of code key pressed
; into AL
mov bl,32h ; High char to check ('Z')
mov bh,10h ; Low char to check ('A')
call ChrRang ; Is AL between 'Z' and 'A'?
jc End_09 ; No, it isn't an alpha key

mov bl,1Dh ; High char
mov bh,1Ah ; Low char
call ChrRang ; Since we are using scan codes
; there are some keys between
; 'A' and 'Z' that aren't alpha
; keys. This check for one
; set of non-alpha keys.

jnc End_09 ; Yes, it isn't an alpha key

mov bl,2Bh ; High char
mov bh,27h ; Low char
call ChrRang ; This checks for the other set
; of non-alpha keys.

jnc End_09 ; Yes, it is in this set, so it
; isn't an alpha key.

mov ax,10 ; Get random number between 1
push ax ; and 10 and push it on the stack
call Random ; Random number between 1 and
; 10 is returned in AX
cmp ax,5 ; Is the number greater than 5?
jg End_09 ; Yes, so leave the key alone

mov ax,0 ; Point ES to low memory (0000)
mov es,ax
mov al,byte ptr es:[417h] ; Get shift flags
test al,3 ; Are any of the shift keys pressed?
jz SetShift ; If not, turn on the shift flag
; for the right shift key.
;Û
; Here we know a shift key is pressed.
;Û
mov cs:SaveShift,al ; Save the shift flags

and byte ptr es:[417h],11111100b ; Clear the shift key
; flags.
jmp CallRest

SetShift:
mov cs:SaveShift,al ; Save the shift flags
or byte ptr es:[417h],01 ; Set the right shift key flag
jmp CallRest

CallRest:
popf ; Restore all registers
pop es ; and call the Int 09h handler
pop dx
pop cx
pop bx
pop ax
pushf
call dword ptr cs:[Old_09_Ofs]

push ax ; Save the regs were gonna use
push es
pushf

mov ax,0 ; Point ES to low memory again
mov es,ax
mov al,cs:SaveShift ; Get the saved flags
mov byte ptr es:[417h],al ; Restore them back to the
; flag status byte in low memory.

popf ; Restore the registers
pop es
pop ax
iret ; Return from the interrupt

End_09:
popf ; Restore all registers
pop es
pop dx
pop cx
pop bx
pop ax
; Jump to the old Int 09
; handler
db 0EAh
Old_09_Ofs dw 0
Old_09_Seg dw 0

SaveShift db 0 ; Byte to save flags to

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ ÛÛ
;ÛÛ Procedure: ChrRang ÛÛ
;ÛÛ ÛÛ
;ÛÛ Call to test if a character is between or included by two characters ÛÛ
;ÛÛ ÛÛ
;ÛÛ To Call: AL = Char to check ÛÛ
;ÛÛ BL = upper match char ÛÛ
;ÛÛ BH = low match char ÛÛ
;ÛÛ Exit: CF clear if valid match ÛÛ
;ÛÛ BL = undefined ÛÛ
;ÛÛ all other registers unchanged ÛÛ
;ÛÛ ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

ChrRang:
cmp al,bh ; Is the char < BH
jc ChrRng1 ; Yes, no match, return with carry
inc bl ; Is the char > BL
cmp al,bl ; Compare with upper limit
cmc ; Invert the carry flag
ChrRng1:
ret

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ ÛÛ
;ÛÛ Procedure: Random ÛÛ
;ÛÛ ÛÛ
;ÛÛ To Call: SP + 4 = High number for random generator ÛÛ
;ÛÛ ÛÛ
;ÛÛ Exit: AX = Random number between 0 and AX ÛÛ
;ÛÛ ÛÛ
;ÛÛ (Taken from Turbo Pascal Random() function) ÛÛ
;ÛÛ ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

Random:
call Rnd2
xor ax,ax
mov bx,sp
mov bx,ss:[bx+2]
or bx,bx
jz RndEnd
xchg ax,dx
div bx
xchg ax,dx

RndEnd:
ret 2

Rnd2:
mov ax,cs:Data_3
mov bx,cs:Data_4
mov cx,ax
mul cs:data_29
shl cx,1
shl cx,1
shl cx,1
add ch,cl
add dx,cx
add dx,bx
shl bx,1
shl bx,1
add dx,bx
add dh,bl
mov cl,5
shl bx,cl
add dh,bl
add ax,1

adc dx,0
mov cs:Data_3,ax
mov cs:Data_4,dx
ret

Data_29 dw 8405h

Data_3 dw 0
Data_4 dw 0

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ Int 2Fh - New Handler ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

Int_2F:
cmp ah,0E0h ; Is this call for us?
jne Continue ; No, Continue with old Int 2Fh
cmp al,00h ; Yes, Is it an installation
jne Continue ; check? No, Continue.
mov al,0FFh ; Yes, set al to FFh
iret ; Interrupt Return

Continue:
; If not for us, go on
; to old Int 2Fh.
db 0EAh
Old_2F_Ofs dw ? ; Old Int 2Fh Offset
Old_2F_Seg dw ? ; Old Int 2Fh Segment


;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ Installation Routine ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

Install:
mov ax,0E000h ; Call Int 2F to check for
int 2Fh ; re-installation
cmp al,0FFh ; Is it already installed?
je Installed ; Yes, Print message and quit
mov ax,352Fh ; No, Get old Int 2F to point
int 21h ; to our Int 2F handler.
mov Old_2F_Ofs,bx ; Save Old Offset
mov Old_2F_Seg,es ; Save Old Segment

mov ax,3509h ; Get old Int 09 vector
int 21h
mov Old_09_Ofs,bx ; Save Old Offset
mov Old_09_Seg,es ; Save Old Segment

call Randomize ; Get random number seed
; (based on the time)

mov ax,cs ; Point ES to the memory
sub ax,0001 ; control block for this
mov es,ax ; program (KaosKeys).

mov ax,word ptr es:[0003] ; Get the size of the memory
sub ax,25h ; block (in paragraphs), and
; subtract 25h paragraphs from
; it (592 bytes).

mov word ptr es:[0003],ax ; Replace block size with
; the smaller value

mov si,word ptr es:[0012h] ; Get amount of memory in the
; machine (in paragraphs).
; A000 is 640k

sub si,25h ; Subtract 25h paragraphs from
; it.
mov es,si ; Make that the ES
mov si,0 ; Point SI and DI to Offset 0
mov di,0

mov cx,500h ; Move 500h bytes to ES:DI
rep movsb ; which is (A000-25:0) from
; DS:SI which is CS:0

push es ; Set DS equal to ES (which
pop ds ; points to the segment where
; we just moved the entire
; program to)

mov ax,252Fh ; Set Int 2F vector to point
mov dx,offset Int_2F ; to our handler at Int_2F
; up towards the top of memory
int 21h ; Set it.

mov ax,2509h ; Set keyboard vector to point
mov dx,offset Int_09 ; to our handler up towards the
; top of memory
int 21h ; Set it.

int 20h ; And quit normally.

Installed:
mov ah,09 ; Print string until '$' or 24h
mov dx,offset Message ; Print data at Message.
int 21h ; Print it
int 20h ; Quit

Randomize:
mov ah,2Ch
int 21h ; DOS Services ah=function 2Ch
; get time, cx=hrs/min, dh=sec
mov cs:Data_3,cx
mov cs:Data_4,dx
ret

Message db 'Hidden Kaos - Copyright (C) 1990 - By Philip Maland',00h
db 0Ah,0Dh,0Ah,0Dh,'Already installed.',0Ah,0Dh,24h

Seg_A ends



end Start