72 lines
1.0 KiB
NASM
72 lines
1.0 KiB
NASM
org 0x7C00
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xor ax, ax
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov sp, 0x7C00
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mov si, 0x400
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loop: mov dx, si
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call dmpdx
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mov al, 0x20
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int 0x10
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int 0x10
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push si
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mov cx, 8
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wloop: lodsw
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xchg al, ah
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mov dx, ax
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push cx
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call dmpdx
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mov al, 0x20
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int 0x10
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pop cx
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loop wloop
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pop si
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mov al, 0x20
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int 0x10
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mov cx, 16
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aloop: lodsb
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cmp al, 0x20
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jnc noadj
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mov al, '.'
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noadj: int 0x10
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loop aloop
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mov al, 0x0A
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int 0x10
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mov al, 0x0D
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int 0x10
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cmp si, 0x500
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jc loop
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hlt: hlt
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jmp hlt
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dmpdx: ; setup bx and ah for int 10h call
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xor bx, bx
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mov ah, 0x0e
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mov cl, 4
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; this double-call is essentially a 4 times repeating loop
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call dmpdx1
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dmpdx1: call dmpdx2
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dmpdx2: ; grab highest nibble from dx
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mov al, dh
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; remove highest nibble from dx
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shl dx, cl
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; shift away second-highest nibble that we accidentally copied
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shr al, cl
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; map 0-9 to ascii codes for '0' to '9'
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add al, 0x30
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; if result is larger than '9', ...
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cmp al, 0x3a
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jl dmpdx3
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; ... add 7 so we continue at 'A'
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add al, 7
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dmpdx3: int 0x10
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ret
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