277 lines
7.6 KiB
Plaintext
277 lines
7.6 KiB
Plaintext
## Copyright (C) 2016 Jeremiah Orians
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## This file is part of stage0.
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##
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## stage0 is free software: you an redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation, either version 3 of the License, or
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## (at your option) any later version.
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##
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## stage0 is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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## You should have received a copy of the GNU General Public License
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## along with stage0. If not, see <http://www.gnu.org/licenses/>.
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# start:
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# Let us first setup our stack
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BC0001 # mov sp,0x100
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B8007E # mov ax,0x7e00
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8ED0 # mov ss,ax
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# Setup segment to shove input
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B80010 # mov ax,0x1000
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8EC0 # mov es,ax
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BD0000 # mov bp,0x0
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# Initialize variables
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B80000 # mov ax,0x0
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BF0100 # mov di,0x1
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BE0000 # mov si,0x0
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# loop:
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E85100 # call read_char
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# Check for C-d
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3C04 # cmp al,0x4
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7505 # jnz 0x25 [Skip over next 2 instructions]
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E8E400 # call execute_code
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EBF4 # jmp loop
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# Check for C-l
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3C0C # cmp al,0xc
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7505 # jnz 0x2e [Skip over next 2 instructions]
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E84600 # call clear_screen
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EBEB # jmp loop
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# Check for [Enter]
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3C0D # cmp al,0xd
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7505 # jnz 0x37 [Skip over next 2 instructions]
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E85800 # call display_newline
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EBE2 # jmp loop
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# Otherwise just print the char
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E82E00 # call print_char
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E88D00 # call hex
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3C00 # cmp al,0x0 [Check if is hex char]
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7CD8 # jl loop
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83FF00 # cmp di,byte +0x0 [Check if toggled]
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740A # jz 0x50 [Skip over next 4 instructions]
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# Process first nibble of pair
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BE0F00 # mov si,0xf
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21C6 # and si,ax
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BF0000 # mov di,0x0
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EBC9 # jmp loop
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# Process second nibble of pair
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C1E604 # shl si,byte 0x4
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83E00F # and ax,byte +0xf
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01F0 # add ax,si
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BF0100 # mov di,0x1
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89EB # mov bx,bp
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# Write out byte
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268807 # mov [es:bx],al
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# Update our pointer
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83C501 # add bp,byte +0x1
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E8C900 # call insert_spacer
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EBB1 # jmp loop
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# print_char:
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B40E # mov ah,0xe
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CD10 # int 0x10
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C3 # ret
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# read_char:
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B400 # mov ah,0x0
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CD16 # int 0x16
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C3 # ret
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# clear_screen:
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# The actual clearing of the screen
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B000 # mov al,0x0
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B406 # mov ah,0x6
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B707 # mov bh,0x7
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B100 # mov cl,0x0
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B500 # mov ch,0x0
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B250 # mov dl,0x50
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B618 # mov dh,0x18
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CD10 # int 0x10
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# The resetting of the cursor
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B402 # mov ah,0x2
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B700 # mov bh,0x0
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B600 # mov dh,0x0
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B200 # mov dl,0x0
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CD10 # int 0x10
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C3 # ret
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# display_newline:
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E81B00 # call get_cursor_position
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80FC0C # cmp ah,0xc
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7E04 # jng 0x99 [Skip over next 2 instructions]
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E81C00 # call word 0xb4
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C3 # ret
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# Move the cursor down if required
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B601 # mov dh,0x1
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00E6 # add dh,ah
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B402 # mov ah,0x2
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B700 # mov bh,0x0
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B200 # mov dl,0x0
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CD10 # int 0x10
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B00D # mov al,0xd
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E8BEFF # call print_char
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C3 # ret
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# get_cursor_position:
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B403 # mov ah,0x3
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B700 # mov bh,0x0
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CD10 # int 0x10
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89D0 # mov ax,dx
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C3 # ret
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# scroll_window:
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B001 # mov al,0x1
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B406 # mov ah,0x6
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B707 # mov bh,0x7
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B100 # mov cl,0x0
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B500 # mov ch,0x0
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B250 # mov dl,0x50
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B618 # mov dh,0x18
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CD10 # int 0x10
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B00D # mov al,0xd
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E89FFF # call print_char
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C3 # ret
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# hex:
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# Deal with line comments starting with #
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3C23 # cmp al,0x23
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742A # jz ascii_comment
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# Deal with line comments starting with ;
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3C3B # cmp al,0x3b
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7426 # jz ascii_comment
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# Deal with all ascii less than '0'
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3C30 # cmp al,0x30
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7C1F # jl ascii_other
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# Deal with '0' through '9'
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3C3A # cmp al,0x3a
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7C12 # jl ascii_num
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# Deal with all ascii less than 'A'
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3C41 # cmp al,0x41
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7C17 # jl ascii_other
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# Deal with 'A' through 'F'
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3C47 # cmp al,0x47
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7C10 # jl ascii_high
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# Deal with all ascii less than 'a'
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3C61 # cmp al,0x61
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7C0F # jl ascii_other
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# Deal with 'a' through 'f'
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3C67 # cmp al,0x67
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7C05 # jl ascii_low
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# Deal with everything else
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EB09 # jmp ascii_other
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# ascii_num:
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2C30 # sub al,0x30
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C3 # ret
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# ascii_low:
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2C57 # sub al,0x57
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C3 # ret
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# ascii_high:
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2C37 # sub al,0x37
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C3 # ret
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# ascii_other:
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B0FF # mov al,0xff
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C3 # ret
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# ascii_comment:
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E872FF # call read_char
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E86AFF # call print_char
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3C0D # cmp al,0xd
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75F6 # jnz ascii_comment
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E8AFFF # call scroll_window
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EBEE # jmp ascii_other
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# execute_code:
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# Clear the screen to be nice
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E868FF # call clear_screen
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# Zero all registers and segments before jump
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B80000 # mov ax,0x0
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BB0000 # mov bx,0x0
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B90000 # mov cx,0x0
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BA0000 # mov dx,0x0
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BE0000 # mov si,0x0
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BF0000 # mov di,0x0
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BD0000 # mov bp,0x0
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8ED8 # mov ds,ax
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8ED0 # mov ss,ax
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8EC0 # mov es,ax
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8EE0 # mov fs,ax
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8EE8 # mov gs,ax
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# Load the code that we input by hand
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680010 # push word 0x1000
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6A00 # push byte +0x0
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# Using intersegment return
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CF # iretw
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# insert_spacer:
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B020 # mov al,0x20
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E834FF # call word 0x68
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C3 # ret
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# done:
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F4 # hlt
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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90 90 90 90 # 4 nops
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55AA # Magic Number
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