9os

Experimental kernel using plan9 ideas for embedded device
git clone git://git.simple-cc.org/9os
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lock.s (408B)

      1 	.file	"lock.s"
      2 /*
      3  * Those functions are currently not used for two reasons:
      4  * 1- We don't have caches and mmu enabled
      5  * 2- We are executing only one execution thread.
      6  */
      7 
      8 	.TEXT
      9 	.GLOBL	lock
     10 
     11 lock:
     12 	MOV	W2,#1
     13 	SEVL
     14 1:
     15 	WFE
     16 	MOV	W1,WZR
     17 	CASA	W1,W2,[x0]
     18 	CBNZ	W1,1B
     19 	RET
     20 
     21 	.TEXT
     22 	.GLOBL	unlock
     23 
     24 unlock:
     25 	STLR	WZR,[X0]
     26 	SEV
     27 	RET
     28 
     29 	.TEXT
     30 	.GLOBL	trylock
     31 
     32 trylock:	// TODO: implement trylock
     33 	MOV	W0,#1
     34 	RET