158 lines
2.4 KiB
Plaintext
158 lines
2.4 KiB
Plaintext
section .realmode
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int_08_ticks_counter: dd 0
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int_08_callback: dd 0
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int_08_isr:
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bits 16
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pushf
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inc dword [cs:int_08_ticks_counter]
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popf
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jmp far [cs:int_08_callback]
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bits 32
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extern getchar_internal
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global _pit_sleep_and_quit_on_keypress
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_pit_sleep_and_quit_on_keypress:
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; Hook int 0x08
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mov edx, dword [0x08*4]
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mov dword [int_08_callback], edx
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mov dword [0x08*4], int_08_isr
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; pit_ticks in edx
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mov edx, dword [esp+4]
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mov dword [int_08_ticks_counter], 0
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; Save GDT in case BIOS overwrites it
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sgdt [.gdt]
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; Save IDT
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sidt [.idt]
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; Load BIOS IVT
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lidt [.rm_idt]
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; Save non-scratch GPRs
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push ebx
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push esi
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push edi
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push ebp
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; Jump to real mode
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jmp 0x08:.bits16
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.bits16:
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bits 16
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mov ax, 0x10
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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mov eax, cr0
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and al, 0xfe
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mov cr0, eax
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jmp 0x00:.cszero
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.cszero:
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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 fs, ax
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mov gs, ax
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mov ss, ax
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sti
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mov byte [.mods], 0
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mov byte [.ascii], 0
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mov byte [.scan], 0
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.loop:
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cmp dword [int_08_ticks_counter], edx
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je .done
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push ecx
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push edx
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mov ah, 0x01
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xor al, al
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int 0x16
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pop edx
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pop ecx
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jz .loop
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; on keypress
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xor ax, ax
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int 0x16
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mov byte [.ascii], al
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mov byte [.scan], ah
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mov ax, 0x0200
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int 0x16
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test al, 0x04
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jz .done
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; ctrl handling
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mov byte [.mods], 0x04
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add byte [.ascii], 0x60
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.done:
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cli
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; Restore GDT
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o32 lgdt [ss:.gdt]
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; Restore IDT
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o32 lidt [ss:.idt]
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; Jump back to pmode
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mov ebx, cr0
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or bl, 1
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mov cr0, ebx
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jmp 0x18:.bits32
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.bits32:
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bits 32
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mov bx, 0x20
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mov ds, bx
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mov es, bx
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mov fs, bx
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mov gs, bx
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mov ss, bx
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; Restore non-scratch GPRs
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pop ebp
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pop edi
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pop esi
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pop ebx
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; Dehook int 0x08
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mov edx, dword [int_08_callback]
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mov dword [0x08*4], edx
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cmp byte [.scan], 0
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je .fail
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push dword [.mods]
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push dword [.ascii]
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push dword [.scan]
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call getchar_internal
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add esp, 3*4
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ret
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.fail:
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xor eax, eax
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ret
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.gdt: dq 0
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.idt: dq 0
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.rm_idt: dw 0x3ff
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dd 0
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.mods: dd 0
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.ascii: dd 0
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.scan: dd 0
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section .note.GNU-stack noalloc noexec nowrite progbits
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