.model tiny
    .386
    locals
    .code
    org 100h

include macro.asm

Start:

    mov dl, 0
    jmp Main

table1  db 32 dup (13), 0, 12 dup (13), 1, 26 dup (13), 2, 3, 13, 4, 7 dup (13), 5, 13, 6, 6 dup (13), 7, 11 dup (13), 8, 9, 13, 10, 7 dup (13), 11, 13, 12, 138 dup (13)
table2  db 1, 14 dup (8), 2, 5 dup (8), 2, 8 dup (8), 3, 4, 5, 6, 7, 8, 3, 4, 5, 6, 7, 8, 1, 13 dup (8), 1, 13 dup (8), 1, 13 dup (8), 1, 13 dup (8), 1, 13 dup (8)

usageMess   db 'r1 [\h] [\i] [\k] [\s] [\u]', 24h
helpMess    db 'This program is for interrupt handler installation for int 2Fh', 24h
installed   db 'Installed', 24h
notInstall  db 'Not installed', 24h
intHandled  db 'Interrupt handled', 24h
notAuthorized   db 'Not authorized', 24h
authorCode  db 'SM', 24h
oldHandler  dd ?

HandleInterrupt proc

;   +-------------------------------------------
;   | The main interruption handler procedure
;   |
;   | On entry:
;   |   dx - shold contain auth-code
;   |
;   | Returns:
;   |   bx - a place where is the resident
;   +-------------------------------------------

    pushf
    push ds
    push cs
    pop ds

    cmp dx, offset authorCode
    jne @@1

    mov bx, cs

@@1:

    pop ds
    jmp oldHandler
    iret

HandleInterrupt endp

Main:

    mov si, 80h
    lodsb
    mov cl, al

Automata:

    lodsb
    dec cl
    cmp cl, 0
    jl Usage

    lea bx, table1
    xlat
    mov ch, al
    mov al, dl
    mov bl, 14
    mul bl
    mov bl, ch
    add al, bl

    lea bx, table2
    xlat

    cmp al, 8
    je Usage
    cmp al, 3
    je PrintHelp
    cmp al, 4
    je InstallRes
    cmp al, 5
    je KillRes
    cmp al, 6
    je Stat
    cmp al, 7
    je UninstallRes
    mov dl, al

    jmp Automata
    ret

Usage:

    printf usageMess
    ret

PrintHelp:

    printf helpMess
    ret

InMemory:

    printf installed
    ret

NotInMemory:

    printf notInstall
    ret

InstallRes:

    xor bx, bx
    mov ax, bx
    lea dx, authorCode
    int 2Fh
    cmp ax, bx
    jne InMemory

    mov ah, 35h
    mov al, 2Fh
    int 21h
    mov word ptr oldHandler, bx
    mov word ptr oldHandler+2, es

    mov ah, 25h
    mov al, 2Fh
    mov dx, offset HandleInterrupt
    int 21h

    mov ah, 31h
    mov al, 0
    mov dx, 17
    int 21h
    ret

KillRes:

    xor bx, bx
    mov ax, bx
    lea dx, authorCode
    int 2Fh

    mov ah, 25h
    mov al, 2Fh
    mov dx, word ptr oldHandler
    mov ds, [word ptr oldHandler+2]
    int 21h

    cmp ax, bx
    jne CleanMemory
    ret

CleanMemory:

;   +------------------------------------------------
;   | Releases 17 paragraphs from a set segment
;   |
;   | On entry:
;   | bx - segment address of memory to be released
;   +------------------------------------------------

    mov ds, bx

    mov ah, 49h
    mov ds, ds:110h
    int 21h
    ret

Stat:

    xor bx, bx
    mov ax, bx
    lea dx, authorCode
    int 2Fh
    cmp ax, bx
    jne InMemory
    je NotInMemory
    ret

UninstallRes:

    xor bx, bx
    mov ax, bx
    lea dx, authorCode
    int 2Fh
    cmp ax, bx
    je NotInMemory

    mov ah, 25h
    mov al, 2Fh
    mov dx, word ptr oldHandler
    mov ds, [word ptr oldHandler+2]
    int 21h

    jmp CleanMemory
    ret

end Start