315 lines
7.2 KiB
NASM
315 lines
7.2 KiB
NASM
;Copyright (c) 1998 - 1999 Microsoft Corporation
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page 85,132
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;*****************************************************************************
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;
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; yielddos.asm
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; DOS TSR to yield when too many get time request float by
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;
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; Copyright Citrix Systems Inc. 1993
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;
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;
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;*****************************************************************************
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TEXT segment public 'CODE'
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assume CS:TEXT,DS:TEXT,ES:TEXT,SS:Nothing
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.286p
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ORG 100h
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main proc far
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jmp init
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main endp
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;**************************************************************************
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; Int21Hook
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;
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; Function: Int 21 Handler for yielddos
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;
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;**************************************************************************
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Int21Hook proc far
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; move current cmd to previous cmd
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push ax
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mov ah,cs:CurrCmd
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mov cs:PrevCmd,ah
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pop ax
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; save current cmd
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mov cs:CurrCmd,ah
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; is request get time?
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cmp ah,2ch
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jne short NotMine
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; move current time to previous time
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push ax
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mov ax,cs:CurrHourMin
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mov cs:PrevHourMin,ax
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mov ax,cs:CurrSec
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mov cs:PrevSec,ax
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pop ax
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; get the current time
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pushf
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call dword ptr cs:[OldInt21]
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pushf
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; save the current time
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push dx
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and dl,0f0h ; look for changes within 16/100 sec
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mov cs:CurrHourMin,cx
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mov cs:CurrSec,dx
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pop dx
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; was the previous cmd Get Time?
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cmp cs:PrevCmd,2ch
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jne short NoYield
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; are the times the same?
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push ax
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mov ax,cs:CurrHourMin
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cmp ax,cs:PrevHourMin
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pop ax
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jne short NoYield
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push ax
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mov ax,cs:CurrSec
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cmp ax,cs:PrevSec
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pop ax
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jne short NoYield
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; yielding if time the same and command repeated
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push ax
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push cx
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mov cx, cs:YieldCount
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kbdJ:
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mov ax,1680h
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int 2fh
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dec cx
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jnz kbdJ
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pop cx
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pop ax
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NoYield:
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popf
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retf 2
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NotMine: ; send to previous Int 21 handler
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jmp dword ptr cs:[OldInt21]
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Int21Hook endp
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;**************************************************************************
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; Int33Hook
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;
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; Function: Int 33 Handler for yielddos
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;
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;**************************************************************************
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Int33Hook proc far
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; is request get button status and mouse position
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cmp ax,0003h
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jne short NotMine33
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; get the mouse information
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pushf
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call dword ptr cs:[OldInt33]
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pushf
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; Count Int33 func 0003
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inc cs:Int33Func3
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push ax
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push cx
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mov cx, cs:YieldCount
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mouseJ:
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mov ax,1680h
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int 2fh
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dec cx
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jnz mouseJ
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pop cx
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pop ax
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popf
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retf 2
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NotMine33: ; send to previous Int 21 handler
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jmp dword ptr cs:[OldInt33]
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Int33Hook endp
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OldInt21 dd 0 ; Old int 21 handler
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OldInt33 dd 0 ; Old int 33 handler
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Int33Func3 dw 0 ; Int33Func3 count
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CurrCmd db 0 ; Current Int 21
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PrevCmd db 0 ; Old Int 21
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CurrHourMin dw 0 ; Current Hour/minutes
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CurrSec dw 0 ; Current Sec/100th Sec
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PrevHourMin dw 0 ; Previous Hour/minutes
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PrevSec dw 0 ; Previous Sec/100th Sec
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YieldCount dw 20 ; Yeild Loop Counter
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ORG $ + 15
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;*
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;* End of resident code and data
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;*
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ResidentMark label byte
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;*
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;* Start of init code and data
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;*
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init:
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; save regs
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push ax
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push bx
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push cx
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push dx
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push si
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; command line arg?
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mov cl, byte ptr ds:[80h]
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cmp cl, 0
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je no_arg
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; set up pointer and counter
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mov si, 81h
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xor bx, bx
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jmp short getfirst
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getnum:
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dec cl
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jz done
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getfirst:
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lodsb
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sub al, "0"
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jb not_int
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cmp al, 9
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ja not_int
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cbw
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xchg ax, bx
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mov dx, 10
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mul dx
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add bx, ax
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jmp getnum
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not_int:
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cmp bx, 0
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je getnum
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done:
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cmp bx, 0
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je no_arg
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mov YieldCount, bx
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no_arg:
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pop si
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pop dx
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pop cx
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pop bx
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pop ax
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; Hook Interrupt 21
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call HookInt21
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; Hook Interrupt 33
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call HookInt33
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StayRes:
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; Free the environment
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xor ax, ax
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xchg ax, word ptr ds:[2ch] ; get env from PSP
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or ax, ax
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jz short skipenv
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push es
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mov es, ax
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mov ah, 49h
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int 21h
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pop es
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skipenv:
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; Keep program running to catch Int 21 Func 3D requests
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mov ax, 3100h
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mov dx, offset ResidentMark
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shr dx,4
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int 21h
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;*****************************************************************************
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;* HookInt21
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;*
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;* Function: Hook Interrupt 21 for yielddos
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;*
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;* Notes:
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;* Saves the Old Int 21 handler for restoring and calling
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;*****************************************************************************
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HookInt21 proc near
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push es
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push bx
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push dx
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mov ax,3521h ; get int 21 value
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int 21h
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mov word ptr [OldInt21],bx
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mov word ptr [OldInt21]+2,es
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mov ax,ds
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mov es,ax
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mov ax,2521h
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mov dx, offset Int21Hook
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int 21h
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pop dx
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pop bx
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pop es
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ret
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HookInt21 endp
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;*****************************************************************************
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;* HookInt33
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;*
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;* Function: Hook Interrupt 33 for yielddos
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;*
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;* Notes:
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;* Saves the Old Int 33 handler for restoring and calling
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;*****************************************************************************
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HookInt33 proc near
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push es
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push bx
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push dx
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mov ax,3533h ; get int 21 value
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int 21h
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mov word ptr [OldInt33],bx
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mov word ptr [OldInt33]+2,es
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mov ax,ds
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mov es,ax
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mov ax,2533h
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mov dx, offset Int33Hook
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int 21h
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pop dx
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pop bx
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pop es
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ret
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HookInt33 endp
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;*
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;* Init DATA
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;* messages and temporary storage discarded after init
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;*
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TEXT ends
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end main
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