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48 lines
1.0 KiB
48 lines
1.0 KiB
[org 0x7c00]
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mov ah, 0x0e
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; attempt 1
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; Will fail again regardless of 'org' because we are still addressing the pointer
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; and not the data it points to
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mov al, "1"
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int 0x10
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mov al, the_secret
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int 0x10
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; attempt 2
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; Having solved the memory offset problem with 'org', this is now the correct answer
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mov al, "2"
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int 0x10
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mov al, [the_secret]
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int 0x10
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; attempt 3
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; As you expected, we are adding 0x7c00 twice, so this is not going to work
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mov al, "3"
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int 0x10
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mov bx, the_secret
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add bx, 0x7c00
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mov al, [bx]
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int 0x10
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; attempt 4
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; This still works because there are no memory references to pointers, so
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; the 'org' mode never applies. Directly addressing memory by counting bytes
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; is always going to work, but it's inconvenient
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mov al, "4"
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int 0x10
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mov al, [0x7c2d]
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int 0x10
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jmp $ ; infinite loop
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the_secret:
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; ASCII code 0x58 ('X') is stored just before the zero-padding.
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; On this code that is at byte 0x2d (check it out using 'xxd file.bin')
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db "X"
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; zero padding and magic bios number
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times 510-($-$$) db 0
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dw 0xaa55
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