limine/common/lib/sleep.asm_bios_ia32

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