global spinlock_acquire:function
global spinlock_release:function
global spinlock_init:function

; spinlock addr in rdi
; low four bytes is ticket number
; high four bytes is turn counter

spinlock_init:
	mov rax, 0
	mov [rdi], rax
	ret

spinlock_acquire:
	mov eax, 1
	lock xadd [rdi], eax   ; eax = my ticket number

	cmp [rdi+4], eax        ; is it my turn?
	je .acquired             ; yes

.retry:
	pause
	cmp [rdi+4], eax        ; is it my turn?
	jne .retry                ; keep waiting
.acquired:
	ret

spinlock_release:
	lock inc dword [rdi+4]
	ret