LXR linux-old/include/linux/timer.h

   1#ifndef _LINUX_TIMER_H
   2#define _LINUX_TIMER_H
   3
   4#include <linux/config.h>
   5#include <linux/list.h>
   6
   7/*
   8 * In Linux 2.4, static timers have been removed from the kernel.
   9 * Timers may be dynamically created and destroyed, and should be initialized
  10 * by a call to init_timer() upon creation.
  11 *
  12 * The "data" field enables use of a common timeout function for several
  13 * timeouts. You can use this field to distinguish between the different
  14 * invocations.
  15 */
  16struct timer_list {
  17        struct list_head list;
  18        unsigned long expires;
  19        unsigned long data;
  20        void (*function)(unsigned long);
  21};
  22
  23extern void add_timer(struct timer_list * timer);
  24extern int del_timer(struct timer_list * timer);
  25
  26#ifdef CONFIG_SMP
  27extern int del_timer_sync(struct timer_list * timer);
  28extern void sync_timers(void);
  29#else
  30#define del_timer_sync(t)       del_timer(t)
  31#define sync_timers()           do { } while (0)
  32#endif
  33
  34/*
  35 * mod_timer is a more efficient way to update the expire field of an
  36 * active timer (if the timer is inactive it will be activated)
  37 * mod_timer(a,b) is equivalent to del_timer(a); a->expires = b; add_timer(a).
  38 * If the timer is known to be not pending (ie, in the handler), mod_timer
  39 * is less efficient than a->expires = b; add_timer(a).
  40 */
  41int mod_timer(struct timer_list *timer, unsigned long expires);
  42
  43extern void it_real_fn(unsigned long);
  44
  45static inline void init_timer(struct timer_list * timer)
  46{
  47        timer->list.next = timer->list.prev = NULL;
  48}
  49
  50static inline int timer_pending (const struct timer_list * timer)
  51{
  52        return timer->list.next != NULL;
  53}
  54
  55/*
  56 *      These inlines deal with timer wrapping correctly. You are 
  57 *      strongly encouraged to use them
  58 *      1. Because people otherwise forget
  59 *      2. Because if the timer wrap changes in future you wont have to
  60 *         alter your driver code.
  61 *
  62 * time_after(a,b) returns true if the time a is after time b.
  63 *
  64 * Do this with "<0" and ">=0" to only test the sign of the result. A
  65 * good compiler would generate better code (and a really good compiler
  66 * wouldn't care). Gcc is currently neither.
  67 */
  68#define time_after(a,b)         ((long)(b) - (long)(a) < 0)
  69#define time_before(a,b)        time_after(b,a)
  70
  71#define time_after_eq(a,b)      ((long)(a) - (long)(b) >= 0)
  72#define time_before_eq(a,b)     time_after_eq(b,a)
  73
  74#endif
  75