41 lines
509 B
NASM
41 lines
509 B
NASM
section .bss
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; drive selected for I/O
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dsknum: resb 1
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; current sector number
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dskseek: resd 1
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; disk buffer for I/O operations
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dskbuf: resb 512
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section .text
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ret: ret
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; select drive
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; IN dl drive number
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dsksel: cmp dl, 1
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jnc ret
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mov al, dl
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and al, 0x02
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ror dl, 1
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ror dl, 1
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cmp dl, byte [dsknum]
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je ret
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call dskrst
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int 3
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ret
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dskrst: call flush
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mov ax, 0xFFFF
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mov [dsknum], al
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mov [dskseek], ax
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mov [dskseek+2], ax
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ret
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; flush buffer if dirty
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flush: ret
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