#if !defined(_RESEARCH_SOURCE) && !defined(_PLAN9_SOURCE)   This header file is an extension of ANSI/POSIX#endif #ifndef __LOCK_H#define __LOCK_H#pragma lib "/$M/lib/ape/libap.a" #include <u.h> typedef struct{	int	val;} Lock; #ifdef __cplusplusextern "C" {#endif extern	void	lock(Lock*);extern	void	unlock(Lock*);extern	int	canlock(Lock*);extern	int	tas(int*); #ifdef __cplusplus}#endif #endif