posix-timers.h

来自「Linux Kernel 2.6.9 for OMAP1710」· C头文件 代码 · 共 99 行

#ifndef _linux_POSIX_TIMERS_H
#define _linux_POSIX_TIMERS_H

#include <linux/spinlock.h>
#include <linux/list.h>

struct k_clock_abs {
	struct list_head list;
	spinlock_t lock;
};
struct k_clock {
	int res;		/* in nano seconds */
	struct k_clock_abs *abs_struct;
	int (*clock_set) (struct timespec * tp);
	int (*clock_get) (struct timespec * tp);
	int (*nsleep) (int flags,
		       struct timespec * new_setting,
		       struct itimerspec * old_setting);
	int (*timer_set) (struct k_itimer * timr, int flags,
			  struct itimerspec * new_setting,
			  struct itimerspec * old_setting);
	int (*timer_del) (struct k_itimer * timr);
	void (*timer_get) (struct k_itimer * timr,
			   struct itimerspec * cur_setting);
};

#if defined(CONFIG_HIGH_RES_TIMERS)

struct now_struct {
	unsigned long jiffies;
	long sub_jiffie;
};

/*
 * The following locking assumes that irq off.
 */
static inline void
posix_get_now (struct now_struct *now)
{
	unsigned long seq;
	
	(now)->jiffies = jiffies;
	do {
		seq = read_seqbegin(&xtime_lock);
		(now)->sub_jiffie = get_arch_cycles((now)->jiffies);
	} while (read_seqretry(&xtime_lock, seq));
	
	while (unlikely(((now)->sub_jiffie - arch_cycles_per_jiffy) > 0)) {
		(now)->sub_jiffie = (now)->sub_jiffie - arch_cycles_per_jiffy;
		(now)->jiffies++;
	}
}

static inline int
posix_time_before (const struct timer_list* t, const struct now_struct* now)
{
	const long diff = (long)t->expires - (long)now->jiffies;

	return (diff < 0) 
		|| ((diff == 0) && (t->sub_expires < now->sub_jiffie)); 
}

static inline void 
posix_bump_timer (struct k_itimer* t, const struct now_struct now) 
{
	t->it_timer.expires += t->it_incr;
	t->it_timer.sub_expires += t->it_sub_incr;
	if ((t->it_timer.sub_expires - arch_cycles_per_jiffy) >= 0) {
		t->it_timer.sub_expires -= arch_cycles_per_jiffy;
		t->it_timer.expires++;
	}
	t->it_overrun++;
}

#else /* defined(CONFIG_HIGH_RES_TIMERS) */

struct now_struct {
	unsigned long jiffies;
};

#define posix_get_now(now) (now)->jiffies = jiffies;
#define posix_time_before(timer, now) \
                      time_before((timer)->expires, (now)->jiffies)

#define posix_bump_timer(timr, now)					\
         do {								\
              long delta, orun;						\
	      delta = now.jiffies - (timr)->it_timer.expires;		\
              if (delta >= 0) {						\
	           orun = 1 + (delta / (timr)->it_incr);		\
	          (timr)->it_timer.expires += orun * (timr)->it_incr;	\
                  (timr)->it_overrun += orun;				\
              }								\
            }while (0)
            
#endif /* defined(CONFIG_HIGH_RES_TIMERS) */

#endif