Sync/arch/uefi_x64/boot.s

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[BITS 32] ;... somehow.
[GLOBAL start]
start:
mov esp, _sys_stack ; Stack pointer!
jmp stublet ; This has a purpse. I don't know what it is, but there is one.
ALIGN 4 ; 4KB alignment, required by GRUB.
mboot: ; This is all magic, and all of it required for GRUB to see our stuff.
MULTIBOOT_ALIGN equ 1<<0
MULTIBOOT_MEM equ 1<<1
MULTIBOOT_AOUT equ 1<<16
MULTIBOOT_MAGIC equ 0x1BADB002
MULTIBOOT_FLAGS equ MULTIBOOT_ALIGN | MULTIBOOT_MEM | MULTIBOOT_AOUT
MULTIBOOT_CHECKSUM equ -(MULTIBOOT_MAGIC + MULTIBOOT_FLAGS)
EXTERN code, bss, end
dd MULTIBOOT_MAGIC
dd MULTIBOOT_FLAGS
dd MULTIBOOT_CHECKSUM
dd mboot
dd code
dd bss
dd end
dd start
stublet: ; Where the kernel stuff goes.
;=====================================
;===Priority: 32 bit Protected Mode===
;=====================================
cli ; Interrupts be gone!
xor cx, cx ; CX - GP, useful here.
kbempty:
in al, 64h ; Read keyboard status
test al, 02h ; Check if the buffer is full
loopnz kbempty ; Wait until it is
mov al, 0d1h ; Prepare a message
out 64h, al ; And then send it to the keyboard (controller)
kbempty2:
in al, 64h ; Read the status again
test al, 02h ; Check if it's processed our message
loopnz kbempty2 ; And wait until it has
mov al, 0dfh ; Prepare a different message, telling it to enable A20
out 60h, al ; Send the message
mov cx, 14h ; Restore the value of CX
wait_kb: ; Insinuate a 25uS delay to allow the processor to catch up
out 0edh, ax
loop wait_kb
mov eax, cr0 ; Read the control register
or al, 1 ; Set bit 1: protected mode
mov cr0, eax ; Set the control register back
jmp $+2 ; Clear the queue
nop ; (jump straight to kernel)
nop
;==================================
;===32-bit Protected Mode active===
;==================================
; Call the kernel
EXTERN kernel_main
call kernel_main
jmp $
[GLOBAL load_gdt]
[EXTERN gp]
load_gdt:
lgdt [gp] ; Load the new 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
[GLOBAL idt_load]
[EXTERN idtp]
idt_load:
lidt [idtp]
ret
SECTION .bss
resb 8192
_sys_stack: