Collection of Tools & Utilities/Collection of Tools and Utilities.iso/system/bootslow.zip/SOURCE.ZIP/SLOW.ASM

Assembly Source File | 1991-08-06 | 7KB | 373 lines

;
;; SlowDown for self-booting software
;;
;; BOOTSLOW
;;
;; Copyright 1991 Alexander R. Pruss
;;
;; May be freely distributed, modified and used provided that no copyright
;; messages are removed, and this sentence together with the next two are
;; always included in unmodified form.  If you like this program a lot, you are
;; invited to show your appreciation by making a tax-deductible donation to
;; the Pro-Life or Anti-Abortion movement, but are under no obligation, moral
;; or otherwise to do so (especially if you disagree with the goals of this
;; movement.)  There is no warranty; use at own risk.
;
DefaultSlowdown = 200
StackSize = 1024

    include macros.inc

BiSeg segment at 0040h
    org 13h
    bios_memory dw ?
BiSeg ends

SillySeg segment at 0ABCDh
    org 80h
    CmdHead db ?
SillySeg ends

ZeroSeg segment at 0
    org 8h*4
Inter8 label dword
Inter8l dw ?
Inter8h dw ?
    org 13h*4
Inter13 label dword
Inter13l dw ?
Inter13h dw ?
ZeroSeg ends

c segment
    org 100h
    assume cs:c,ss:NOTHING

StartResident:

ResidentSize = offset EndResident - offset StartResident
ResInK = (ResidentSize+1023)/1024

TOP:
    jmp Install

disk_level dw 0
factor dw DefaultSlowdown

old8 label dword
o8l dw ?
o8h dw ?

old13 label dword
o13l dw ?
o13h dw ?

    assume ds:NOTHING, es:NOTHING, cs:c
i8h:
    cmp cs:disk_level,0
    jz SlowDown
GoThru8:
    jmp dword ptr cs:old8

SlowDown:
    push cx
    push ax
    mov al,3
    mov cx,cs:factor
LoopTop:
    mul al
    add ax,cs:o8h
    sub ax,cs:o8l
    mul al
    mul al
    mul al
    loop LoopTop
    pop ax
    pop cx
    jmp GoThru8

i13h:
    pushf
    inc cs:disk_level
    call dword ptr cs:old13
    pushf
    dec cs:disk_level
    popf
    retf 2

EndResident:

         assume ds:c, es:NOTHING, cs:c
getAXd proc near
    L1:  xor ax,ax
         xor bx,bx
         cmp si,cx
         jae R1
         mov bl,[si]
         inc si
         cmp bl,'0'
         jb L1
         cmp bl,'9'
         ja L1
         sub bl,'0'
         mov al,bl
    L2:  cmp si,cx
         jae R1
         mov bl,[si]
         inc si
         cmp bl,'0'
         jb R1
         cmp bl,'9'
         ja R1
         sub bl,'0'
         mov dx,10
         mul dx
         add ax,bx
         jmp L2
    R1:  ret
getAXd endp

         assume ds:c, es:NOTHING, cs:c
_puts proc near
top:
    mov bx,1
    mov dx,si
    mov ah,WriteHandle
    int 21h
    ret
_puts endp

DiskCheckNo:
    mov disk_check,0
    jmp parsetop

OutOfMemory:
    Puts NoMem
    mov ax,4c10h
    int 21h

;;
;; Installation
;;

Install:
    assume ds:c
    cld

    Puts copyright

    cmp sp,offset stack_bottom+StackSize
    jbe OutOfMemory

    mov sp,offset stack_bottom+StackSize
    assume es:ZeroSeg
    Clear ax
    mov es,ax
    mov ax,es:bios_memory
    sub ax,ResInK         ; subtract size of resident module in Kb
    mov NewMem,ax         ; save new total memory size
    mov bx,1024/16
    mul bx                ; ax is total memory in paragraphs
    mov bx,cs
    add bx,(stack_bottom-TOP+100h+StackSize+2+15)/16   ; paragraph of end of prog
    cmp ax,bx
    jb OutOfMemory
    sub ax,10h            ; resident starts now at ax:0100h
    mov NewSeg,ax         ; save resident segment

    assume ds:SillySeg, es:NOTHING
    Clear ch
    mov cl,CmdHead
    assume ds:c
    mov si,81h
    add cx,si
parsetop:
    cmp si,cx
    jae PARSER_DONE
    lodsb
    cmp al,'d'
    jz DiskCheckNo
    cmp al,'D'
    jz DiskCheckNo
    cmp al,'0'
    jb parsetop
    cmp al,'9'
    ja parsetop
    dec si
    call getAXd
    mov factor,AX
PARSER_DONE:

;; Load interrupt table now ;;

    mov ax,OpenRDOnly
    mov dx,offset filename
    int 21h
    jc _openerror
    mov bx,ax
    mov ah,ReadHandle
    mov cx,4*256
    mov dx,offset itable
    int 21h
    pushf
    mov ah,CloseHandle
    int 21h
    popf
    jnc Nopenerror

_openerror: jmp openerror
_Abort: jmp abort

Nopenerror:

;; Load boot sector ;;

    Puts drive_q
g1:
    DOSGetch
    cmp al,01bh
    jz _Abort
    or al,TOLOWER
    cmp al,'a'
    jb g1
    cmp al,'z'
    ja g1
    sub al,'a'
    mov bx,offset bootsec
    mov cx,1
    Clear dx
    int 25h
    jnc NLowLevelError

jmp LowLevelError

NLowLevelError:
    Puts booting

;;
;; We're unstoppable now!
;;

    Clear ax
    mov es,ax
    assume es:ZeroSeg

;; Copy interrupt table

    mov si,offset itable
    Clear di
    mov cx,256*4/2
    cli
rep movsw
    sti

;;
;; Copy boot sector (es=0000)
;;
    mov si,offset bootsec
    mov di,BootPos
    mov cx,512/2
rep movsw

;;
;; (es=0000)
;; Save original interrupts
;;
    push es
    pop ds
    assume ds:ZeroSeg, es:NOTHING

    les ax,dword ptr Inter8
    mov cs:o8l,ax
    mov cs:o8h,es
    les ax,dword ptr Inter13
    mov cs:o13l,ax
    mov cs:o13h,es

    push cs
    pop ds
    assume ds:c

;;
;; Copy to high memory, adjusting maximum memory available
;;

    Clear ax
    mov es,ax

    assume es:ZeroSeg
    mov ax,NewMem
    mov es:bios_memory,ax

    assume es:NOTHING
    mov es,NewSeg
    mov cx,(EndResident-StartResident+1)/2
    mov si,offset StartResident
    mov di,si
rep movsw      ; Copy to high memory

;; O.K.  The memory is all set up.  Just need to put in the interrupt
;; tables

;; es points to the new segment

    Clear ax
    mov ds,ax
    assume ds:ZeroSeg
    cli
    mov Inter8l,offset i8h
    mov Inter8h,es
    cmp cs:disk_check,0
    jz ND
    mov Inter13l,offset i13h
    mov Inter13h,es
ND:
    sti

;; Well, well, well.  All done, almost.  Just set the registers and jump.
    Clear ax
    cli
    mov ss,ax
    mov sp,BootPos-2
    sti
    db 0EAh  ; Far jump
    dw BootPos
    dw 0000
;; We're in! ;;


LowLevelError:
    Puts ll_error
    mov ax,4c01h
    int 21h

openerror:
    Puts cantopen
    mov ax,4c02h
    int 21h

abort:
    Puts aborted
    mov ax,4c00h
    int 21h

String   copyright, <'Self-Booting Disk Slowdown.', CR,LF, '(C) Copyright 1991 Alexander Pruss.', CR,LF>
String   NoMem, <'Not enough memory.', CR,LF>
String   cantopen, <'Error reading boot.itb.',CR,LF>
String   drive_q, <'Choose DOS drive to boot: (A,B,C,etc.), ESC to abort.', CR,LF>
String   aborted, <'Aborted.',CR,LF>
String   ll_error, <'Error reading boot sector.',CR,LF>
String   booting, <'Booting...',CR,LF>
filename db 'boot.itb',00
disk_check db 1
NewSeg   dw ?
NewMem   dw ?
bootsec label byte
itable = bootsec+512

stack_bottom = itable+1024+512   ; extra 512 for safety

c ends

end TOP