2.9BSD - /usr/src/lib/c/sys/lock.s

   1: / error	= lock(flag)
   2: 
   3: .globl  _lock, cerror
   4: 
   5: _lock:
   6:         mov     r5,-(sp)
   7:         mov     sp,r5
   8:         mov     4(r5),0f
   9:         sys     0; 9f
  10:         .data
  11: 9:
  12:         sys     lock; 0:..
  13:         .text
  14:         bec     1f
  15:         jmp     cerror
  16: 1:
  17:         mov     (sp)+,r5
  18:         rts     pc

Defined functions