timer.h

基于组件方式开发操作系统的OSKIT源代码

#ifndef _LINUX_TIMER_H
#define _LINUX_TIMER_H

/*
 * Old-style timers. Please don't use for any new code.
 *
 * Numbering of these timers should be consecutive to minimize
 * processing delays. [MJ]
 */

#define BLANK_TIMER	0	/* Console screen-saver */
#define BEEP_TIMER	1	/* Console beep */
#define RS_TIMER	2	/* RS-232 ports */
#define SWAP_TIMER	3	/* Background pageout */
#define BACKGR_TIMER    4	/* io_request background I/O */
#define HD_TIMER	5	/* Old IDE driver */
#define FLOPPY_TIMER	6	/* Floppy */
#define QIC02_TAPE_TIMER 7	/* QIC 02 tape */
#define MCD_TIMER	8	/* Mitsumi CDROM */
#define GSCD_TIMER	9	/* Goldstar CDROM */
#define COMTROL_TIMER	10	/* Comtrol serial */
#define DIGI_TIMER	11	/* Digi serial */
#define GDTH_TIMER	12	/* Ugh - gdth scsi driver */

#define COPRO_TIMER	31	/* 387 timeout for buggy hardware (boot only) */

struct timer_struct {
	unsigned long expires;
	void (*fn)(void);
};

extern unsigned long timer_active;
extern struct timer_struct timer_table[32];

/*
 * This is completely separate from the above, and is the
 * "new and improved" way of handling timers more dynamically.
 * Hopefully efficient and general enough for most things.
 *
 * The "hardcoded" timers above are still useful for well-
 * defined problems, but the timer-list is probably better
 * when you need multiple outstanding timers or similar.
 *
 * The "data" field is in case you want to use the same
 * timeout function for several timeouts. You can use this
 * to distinguish between the different invocations.
 */
struct timer_list {
	struct timer_list *next; /* MUST be first element */
	struct timer_list *prev;
	unsigned long expires;
	unsigned long data;
	void (*function)(unsigned long);
};

extern void add_timer(struct timer_list * timer);
extern int  del_timer(struct timer_list * timer);

/*
 * mod_timer is a more efficient way to update the expire field of an
 * active timer (if the timer is inactive it will be activated)
 * mod_timer(a,b) is equivalent to del_timer(a); a->expires = b; add_timer(a)
 */
void mod_timer(struct timer_list *timer, unsigned long expires);

extern void it_real_fn(unsigned long);

extern inline void init_timer(struct timer_list * timer)
{
	timer->next = NULL;
	timer->prev = NULL;
}

extern inline int timer_pending(struct timer_list * timer)
{
	return timer->prev != NULL;
}

/*
 *	These inlines deal with timer wrapping correctly. You are 
 *	strongly encouraged to use them
 *	1. Because people otherwise forget
 *	2. Because if the timer wrap changes in future you wont have to
 *	   alter your driver code.
 *
 * Do this with "<0" and ">=0" to only test the sign of the result. A
 * good compiler would generate better code (and a really good compiler
 * wouldn't care). Gcc is currently neither.
 */
#define time_after(a,b)		((long)(b) - (long)(a) < 0)
#define time_before(a,b)	time_after(b,a)

#define time_after_eq(a,b)	((long)(a) - (long)(b) >= 0)
#define time_before_eq(a,b)	time_after_eq(b,a)

#endif