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bits 32 ; nasm 32-bit mode
section .text
; multiboot header
align 4
dd 0x1BADB002
dd 0x00
dd - (0x1BADB002 + 0x00) ; checksum
global flush_gdt
global read_port
global write_port
global load_idt
global keyboard_handler
global start
extern kernel_entrypoint
extern handle_keypress
extern gdt_pointer
flush_gdt:
lgdt [gdt_pointer]
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp 0x08:flush
flush:
ret
read_port:
mov edx, [esp + 4]
in al, dx
ret
write_port:
mov edx, [esp + 4]
mov al, [esp + 4 + 4]
out dx, al
ret
load_idt:
mov edx, [esp + 4]
lidt [edx]
sti
ret
keyboard_handler:
call handle_keypress
iretd
start:
cli
mov esp, stack_space
call kernel_entrypoint
hlt
section .bss
resb 8192
stack_space:
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