/* $Id: semaphore-helper.h,v 1.3 2001/03/26 15:00:33 orjanf Exp $
   *
   * SMP- and interrupt-safe semaphores helper functions. Generic versions, no
   * optimizations whatsoever... 
   *
   */
  
  #ifndef _ASM_SEMAPHORE_HELPER_H
  #define _ASM_SEMAPHORE_HELPER_H
  
  #include <asm/atomic.h>
  #include <linux/errno.h>
  
  #define read(a) ((a)->counter)
  #define inc(a) (((a)->counter)++)
  #define dec(a) (((a)->counter)--)
  
  #define count_inc(a) ((*(a))++)
  
  /*
   * These two _must_ execute atomically wrt each other.
   */
  extern inline void wake_one_more(struct semaphore * sem)
  {
  	atomic_inc(&sem->waking);
  }
  
  extern inline int waking_non_zero(struct semaphore *sem)
  {
  	unsigned long flags;
  	int ret = 0;
  
  	local_save_flags(flags);
  	local_irq_disable();
  	if (read(&sem->waking) > 0) {
  		dec(&sem->waking);
  		ret = 1;
  	}
  	local_irq_restore(flags);
  	return ret;
  }
  
  extern inline int waking_non_zero_interruptible(struct semaphore *sem,
  						struct task_struct *tsk)
  {
  	int ret = 0;
  	unsigned long flags;
  
  	local_save_flags(flags);
  	local_irq_disable();
  	if (read(&sem->waking) > 0) {
  		dec(&sem->waking);
  		ret = 1;
  	} else if (signal_pending(tsk)) {
  		inc(&sem->count);
  		ret = -EINTR;
  	}
  	local_irq_restore(flags);
  	return ret;
  }
  
  extern inline int waking_non_zero_trylock(struct semaphore *sem)
  {
          int ret = 1;
  	unsigned long flags;
  
  	local_save_flags(flags);
  	local_irq_disable();
  	if (read(&sem->waking) <= 0)
  		inc(&sem->count);
  	else {
  		dec(&sem->waking);
  		ret = 0;
  	}
  	local_irq_restore(flags);
  	return ret;
  }
  
  #endif /* _ASM_SEMAPHORE_HELPER_H */