mutex_trylock.h

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/* PROLOG END TAG zYx                                              */
#ifndef _PPU_MUTEX_TRYLOCK_H_
#define _PPU_MUTEX_TRYLOCK_H_

#include <ppu_intrinsics.h>
#include "sync_utils.h"
#include "mutex.h"
#include "trace_libsync.h"

/**
 * mutex_trylock - acquire a lock, or return immediately.
 * @lock: handle to effective address of lock variable.
 *
 * Description: Acquire a lock, or return immediately 
 * without polling for availability.
 *
 * Context: The application should not call this interface 
 * from a tight loop!!  Use spin_lock() instead.
 *
 * Attempt to immediately aquire a lock at a location in system memory,
 * and return 1 if the lock was aquired or 0 otherwise.
 */
static __inline int _mutex_trylock (mutex_ea_t lock)
{
  int val;
  int ret = 0;
  void *p;

  SYNC_ULL_TO_PTR(lock, p);

  do {
    val = (int)__lwarx(p);
    if (val) break;
  } while ((ret = __stwcx(p, (unsigned int)1)) == 0);
  __isync();

  TRACE_MUTEX_TRYLOCK(lock,ret);

  return (ret);
}

#endif /* _PPU_MUTEX_TRYLOCK_H_ */