times.h

来自「Linux Kernel 2.6.9 for OMAP1710」· C头文件 代码 · 共 86 行

#ifndef _LINUX_TIMES_H
#define _LINUX_TIMES_H

#ifdef __KERNEL__
#include <linux/timex.h>
#include <asm/div64.h>
#include <asm/types.h>
#include <asm/param.h>

static inline clock_t jiffies_to_clock_t(long x)
{
#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
	return x / (HZ / USER_HZ);
#else
	u64 tmp = (u64)x * TICK_NSEC;
	do_div(tmp, (NSEC_PER_SEC / USER_HZ));
	return (long)tmp;
#endif
}

static inline unsigned long clock_t_to_jiffies(unsigned long x)
{
#if (HZ % USER_HZ)==0
	if (x >= ~0UL / (HZ / USER_HZ))
		return ~0UL;
	return x * (HZ / USER_HZ);
#else
	u64 jif;

	/* Don't worry about loss of precision here .. */
	if (x >= ~0UL / HZ * USER_HZ)
		return ~0UL;

	/* .. but do try to contain it here */
	jif = x * (u64) HZ;
	do_div(jif, USER_HZ);
	return jif;
#endif
}

static inline u64 jiffies_64_to_clock_t(u64 x)
{
#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
	do_div(x, HZ / USER_HZ);
#else
	/*
	 * There are better ways that don't overflow early,
	 * but even this doesn't overflow in hundreds of years
	 * in 64 bits, so..
	 */
	x *= TICK_NSEC;
	do_div(x, (NSEC_PER_SEC / USER_HZ));
#endif
	return x;
}
#endif

static inline u64 nsec_to_clock_t(u64 x)
{
#if (NSEC_PER_SEC % USER_HZ) == 0
	do_div(x, (NSEC_PER_SEC / USER_HZ));
#elif (USER_HZ % 512) == 0
	x *= USER_HZ/512;
	do_div(x, (NSEC_PER_SEC / 512));
#else
	/*
         * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
         * overflow after 64.99 years.
         * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
         */
	x *= 9;
	do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2))
	                          / USER_HZ));
#endif
	return x;
}

struct tms {
	clock_t tms_utime;
	clock_t tms_stime;
	clock_t tms_cutime;
	clock_t tms_cstime;
};

#endif