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/*
* $OpenBSD: _atomic_lock.S,v 1.1 1998/11/09 03:13:14 d Exp $
*/
#include "SYS.h"
/*
* Atomicly lock a location with an identifier provided the location
* is not currently locked.
*
* long _atomic_lock(long *a0);
* v0 will contain the return value (zero if lock obtained).
*/
/*
* XXXXXX THIS IS LOCK FUNCTION IS TOTALLY BOGUS XXXXXXXXX
* pefo@ says that for R4000 processors, there is a way to do this
* atomically, but for R3000 you will need to context switch.
* Specifically he says the 'll' and 'sc' instructions can be used for mips2.
*/
LEAF(_atomic_lock)
.set noreorder
.set nomacro
/* Get the existing lock value and lock memory: */
ori t0,zero,1
lw v0,0(a0)
sw t0,0(a0)
j ra
nop
.set macro
.set reorder
END(_atomic_lock)
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