jiffies.h

来自「Linux Kernel 2.6.9 for OMAP1710」· C头文件 代码 · 共 54 行

#ifndef _LINUX_JIFFIES_H
#define _LINUX_JIFFIES_H

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <asm/system.h>
#include <asm/param.h>			/* for HZ */

/*
 * The 64-bit value is not volatile - you MUST NOT read it
 * without sampling the sequence number in xtime_lock.
 * get_jiffies_64() will do this for you as appropriate.
 */
extern u64 jiffies_64;
extern unsigned long volatile jiffies;

#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void);
#else
static inline u64 get_jiffies_64(void)
{
	return (u64)jiffies;
}
#endif

/*
 *	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 won't have to
 *	   alter your driver code.
 *
 * time_after(a,b) returns true if the time a is after time b.
 *
 * 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)		\
	(typecheck(unsigned long, a) && \
	 typecheck(unsigned long, b) && \
	 ((long)(b) - (long)(a) < 0))
#define time_before(a,b)	time_after(b,a)

#define time_after_eq(a,b)	\
	(typecheck(unsigned long, a) && \
	 typecheck(unsigned long, b) && \
	 ((long)(a) - (long)(b) >= 0))
#define time_before_eq(a,b)	time_after_eq(b,a)

#endif