jiffies.h

这是leon3处理器的交叉编译链

#ifndef _LINUX_JIFFIES_H
#define _LINUX_JIFFIES_H

#include <asm-leon/types.h>
#include <asm-leon/clock.h>
#include <asm-leon/linkage.h>

/* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, the we can
 * improve accuracy by shifting LSH bits, hence calculating:
 *     (NOM << LSH) / DEN
 * This however means trouble for large NOM, because (NOM << LSH) may no
 * longer fit in 32 bits. The following way of calculating this gives us
 * some slack, under the following conditions:
 *   - (NOM / DEN) fits in (32 - LSH) bits.
 *   - (NOM % DEN) fits in (32 - LSH) bits.
 */
#define SH_DIV(NOM,DEN,LSH) (   ((NOM / DEN) << LSH)                    \
                             + (((NOM % DEN) << LSH) + DEN / 2) / DEN)

/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */
#define TICK_NSEC (SH_DIV (1000000UL * 1000, (HZ<<8), 8))

/*
 * The 64-bit value is not volatile - you MUST NOT read it
 * without sampling the sequence number in xtime_lock.
 */
extern u64 jiffies_64;
extern struct timespec xtime __attribute__ ((aligned (16)));
#define jiffies (*((unsigned long *)(((unsigned long)(&jiffies_64))+4)))

/*
 *	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)

/*
 * Have the 32 bit jiffies value wrap 5 minutes after boot
 * so jiffies wrap bugs show up earlier.
 */
#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))

static inline void
set_normalized_timespec (struct timespec *ts, time_t sec, long nsec)
{
	while (nsec > NSEC_PER_SEC) {
		nsec -= NSEC_PER_SEC;
		++sec;
	}
	while (nsec < 0) {
		nsec += NSEC_PER_SEC;
		--sec;
	}
	ts->tv_sec = sec;
	ts->tv_nsec = nsec;
}

#endif