37 lines
615 B
NASM
37 lines
615 B
NASM
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[BITS 32]
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[ORG 0x400000]
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xchg bx,bx
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mov edi, 0xB8000
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mov ecx, 80*25
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mov eax, 0x2f00
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rep stosw
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mov edi, 0xB8000
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mov esi, str0
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mov ecx, str0_end - str0
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mov eax, 0x2f00
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.loop:
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lodsb
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stosw
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loop .loop
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mov edi, 0xB8000 + 160 - 2
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.key_loop:
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mov eax, 1 ; command = 01h, get scancode
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int 0x21 ; OS call
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cmp al, 0x3B ; F1
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je .exit
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cmp al, 0x3C ; F2
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je .crash
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cmp ah, 0x00
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je .key_loop
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mov byte [edi], ah ; ASCII value
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add edi, 2
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jmp .key_loop
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.exit:
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mov eax, 0x1337 ; Exit code/Return value
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int 0x30 ; Exit
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.crash:
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jmp 0x00000000
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str0: db "Running usermode program from disk! Press F1 to exit. Press F2 to crash."
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str0_end:
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