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.set ALIGN, 1<<0
.set MEMINFO, 1<<1
.set FLAGS, ALIGN | MEMINFO
.set MAGIC, 0x1BADB002
.set CHECKSUM, -(MAGIC + FLAGS)
.section .multiboot
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM
.global _start
.global load_gdt
.global load_idt
.global enable_interrupts
.global ioport_in
.global ioport_out
load_gdt:
movl 4(%esp), %edx
lgdt (%edx)
ret
load_idt:
movl 4(%esp), %edx
lidt (%edx)
sti
ret
ioport_in:
movl 4(%esp),%edx
in %dx,%al
ret
ioport_out:
movl 4(%esp),%edx
movl 8(%esp),%eax
outb %al,%dx
ret
.set CODE_SEGMENT, 0x08
.set DATA_SEGMENT, 0x10
.section .bss
.align 16
stack_bottom:
.skip 16384
stack_top:
.section .text
.type _start, @function
_start:
call init_gdt_table
ljmp $CODE_SEGMENT, $code
code:
movw $DATA_SEGMENT, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
movl $stack_top, %esp
cli
call _init
call kernel_main
hlt
.size _start, . - _start
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