pd.if.org Git - zos/blob - spinlock.s

   1 global spinlock_acquire:function
   2 global spinlock_release:function
   3 global spinlock_init:function
   4
   5 ; spinlock addr in rdi
   6 ; low four bytes is ticket number
   7 ; high four bytes is turn counter
   8
   9 spinlock_init:
  10         mov rax, 0
  11         mov [rdi], rax
  12         ret
  13
  14 spinlock_acquire:
  15         mov eax, 1
  16         lock xadd [rdi], eax   ; eax = my ticket number
  17
  18         cmp [rdi+4], eax        ; is it my turn?
  19         je .acquired             ; yes
  20
  21 .retry:
  22         pause
  23         cmp [rdi+4], eax        ; is it my turn?
  24         jne .retry                ; keep waiting
  25 .acquired:
  26         ret
  27
  28 spinlock_release:
  29         lock inc dword [rdi+4]
  30         ret