#ifndef _LINUX_JIFFIES_H

#define _LINUX_JIFFIES_H

#include <linux/math64.h>

#include <linux/kernel.h>

#include <linux/types.h>

#include <linux/time.h>

#include <linux/timex.h>

#include <asm/param.h>			/* for HZ */

/*

 * The following defines establish the engineering parameters of the PLL

 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz

 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the

 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the

 * nearest power of two in order to avoid hardware multiply operations.

 */

#if HZ >= 12 && HZ < 24

# define SHIFT_HZ	4

#elif HZ >= 24 && HZ < 48

# define SHIFT_HZ	5

#elif HZ >= 48 && HZ < 96

# define SHIFT_HZ	6

#elif HZ >= 96 && HZ < 192

# define SHIFT_HZ	7

#elif HZ >= 192 && HZ < 384

# define SHIFT_HZ	8

#elif HZ >= 384 && HZ < 768

# define SHIFT_HZ	9

#elif HZ >= 768 && HZ < 1536

# define SHIFT_HZ	10

#elif HZ >= 1536 && HZ < 3072

# define SHIFT_HZ	11

#elif HZ >= 3072 && HZ < 6144

# define SHIFT_HZ	12

#elif HZ >= 6144 && HZ < 12288

# define SHIFT_HZ	13

#else

# error Invalid value of HZ.

#endif

/* LATCH is used in the interval timer and ftape setup. */

#define LATCH  ((CLOCK_TICK_RATE + HZ/2) / HZ)	/* For divider */

/* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, then 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))

/* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */

#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))

/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */

#define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8))

/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */

#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)

/* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and	*/

/* a value TUSEC for TICK_USEC (can be set bij adjtimex)		*/

#define TICK_USEC_TO_NSEC(TUSEC) (SH_DIV (TUSEC * USER_HZ * 1000, ACTHZ, 8))

/* some arch's have a small-data section that can be accessed register-relative

 * but that can only take up to, say, 4-byte variables. jiffies being part of

 * an 8-byte variable may not be correctly accessed unless we force the issue

 */

#define __jiffy_data  __attribute__((section(".data")))

/*

 * The 64-bit value is not atomic - 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 __jiffy_data jiffies_64;

extern unsigned long volatile __jiffy_data 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)

#define time_in_range(a,b,c) \

	(time_after_eq(a,b) && \

	 time_before_eq(a,c))

/* Same as above, but does so with platform independent 64bit types.

 * These must be used when utilizing jiffies_64 (i.e. return value of

 * get_jiffies_64() */

#define time_after64(a,b)	\

	(typecheck(__u64, a) &&	\

	 typecheck(__u64, b) && \

	 ((__s64)(b) - (__s64)(a) < 0))

#define time_before64(a,b)	time_after64(b,a)

#define time_after_eq64(a,b)	\

	(typecheck(__u64, a) && \

	 typecheck(__u64, b) && \

	 ((__s64)(a) - (__s64)(b) >= 0))

#define time_before_eq64(a,b)	time_after_eq64(b,a)

/*

 * These four macros compare jiffies and 'a' for convenience.

 */

/* time_is_before_jiffies(a) return true if a is before jiffies */

#define time_is_before_jiffies(a) time_after(jiffies, a)

/* time_is_after_jiffies(a) return true if a is after jiffies */

#define time_is_after_jiffies(a) time_before(jiffies, a)

/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/

#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)

/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/

#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, 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))

/*

 * Change timeval to jiffies, trying to avoid the

 * most obvious overflows..

 *

 * And some not so obvious.

 *

 * Note that we don't want to return LONG_MAX, because

 * for various timeout reasons we often end up having

 * to wait "jiffies+1" in order to guarantee that we wait

 * at _least_ "jiffies" - so "jiffies+1" had better still

 * be positive.

 */

#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)

extern unsigned long preset_lpj;

/*

 * We want to do realistic conversions of time so we need to use the same

 * values the update wall clock code uses as the jiffies size.  This value

 * is: TICK_NSEC (which is defined in timex.h).  This

 * is a constant and is in nanoseconds.  We will use scaled math

 * with a set of scales defined here as SEC_JIFFIE_SC,  USEC_JIFFIE_SC and

 * NSEC_JIFFIE_SC.  Note that these defines contain nothing but

 * constants and so are computed at compile time.  SHIFT_HZ (computed in

 * timex.h) adjusts the scaling for different HZ values.

 * Scaled math???  What is that?

 *

 * Scaled math is a way to do integer math on values that would,

 * otherwise, either overflow, underflow, or cause undesired div

 * instructions to appear in the execution path.  In short, we "scale"

 * up the operands so they take more bits (more precision, less

 * underflow), do the desired operation and then "scale" the result back

 * by the same amount.  If we do the scaling by shifting we avoid the

 * costly mpy and the dastardly div instructions.

 * Suppose, for example, we want to convert from seconds to jiffies

 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE.  The

 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We

 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we

 * might calculate at compile time, however, the result will only have

 * about 3-4 bits of precision (less for smaller values of HZ).

 *

 * So, we scale as follows:

 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);

 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;

 * Then we make SCALE a power of two so:

 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;

 * Now we define:

 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))

 * jiff = (sec * SEC_CONV) >> SCALE;

 *

 * Often the math we use will expand beyond 32-bits so we tell C how to

 * do this and pass the 64-bit result of the mpy through the ">> SCALE"

 * which should take the result back to 32-bits.  We want this expansion

 * to capture as much precision as possible.  At the same time we don't

 * want to overflow so we pick the SCALE to avoid this.  In this file,

 * that means using a different scale for each range of HZ values (as

 * defined in timex.h).

 *

 * For those who want to know, gcc will give a 64-bit result from a "*"

 * operator if the result is a long long AND at least one of the

 * operands is cast to long long (usually just prior to the "*" so as

 * not to confuse it into thinking it really has a 64-bit operand,

 * which, buy the way, it can do, but it takes more code and at least 2

 * mpys).

 * We also need to be aware that one second in nanoseconds is only a

 * couple of bits away from overflowing a 32-bit word, so we MUST use

 * 64-bits to get the full range time in nanoseconds.

 */

/*

 * Here are the scales we will use.  One for seconds, nanoseconds and

 * microseconds.

 *

 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and

 * check if the sign bit is set.  If not, we bump the shift count by 1.

 * (Gets an extra bit of precision where we can use it.)

 * We know it is set for HZ = 1024 and HZ = 100 not for 1000.

 * Haven't tested others.

 * Limits of cpp (for #if expressions) only long (no long long), but

 * then we only need the most signicant bit.

 */

#define SEC_JIFFIE_SC (31 - SHIFT_HZ)

#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)

#undef SEC_JIFFIE_SC

#define SEC_JIFFIE_SC (32 - SHIFT_HZ)

#endif

#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)

#define USEC_JIFFIE_SC (SEC_JIFFIE_SC + 19)

#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\

                                TICK_NSEC -1) / (u64)TICK_NSEC))

#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\

                                        TICK_NSEC -1) / (u64)TICK_NSEC))

#define USEC_CONVERSION  \

                    ((unsigned long)((((u64)NSEC_PER_USEC << USEC_JIFFIE_SC) +\

                                        TICK_NSEC -1) / (u64)TICK_NSEC))

/*

 * USEC_ROUND is used in the timeval to jiffie conversion.  See there

 * for more details.  It is the scaled resolution rounding value.  Note

 * that it is a 64-bit value.  Since, when it is applied, we are already

 * in jiffies (albit scaled), it is nothing but the bits we will shift

 * off.

 */

#define USEC_ROUND (u64)(((u64)1 << USEC_JIFFIE_SC) - 1)

/*

 * The maximum jiffie value is (MAX_INT >> 1).  Here we translate that

 * into seconds.  The 64-bit case will overflow if we are not careful,

 * so use the messy SH_DIV macro to do it.  Still all constants.

 */

#if BITS_PER_LONG < 64

# define MAX_SEC_IN_JIFFIES \

	(long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)

#else	/* take care of overflow on 64 bits machines */

# define MAX_SEC_IN_JIFFIES \

	(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)

#endif

/*

 * Convert various time units to each other:

 */

extern unsigned int jiffies_to_msecs(const unsigned long j);

extern unsigned int jiffies_to_usecs(const unsigned long j);

extern unsigned long msecs_to_jiffies(const unsigned int m);

extern unsigned long usecs_to_jiffies(const unsigned int u);

extern unsigned long timespec_to_jiffies(const struct timespec *value);

extern void jiffies_to_timespec(const unsigned long jiffies,

				struct timespec *value);

extern unsigned long timeval_to_jiffies(const struct timeval *value);

extern void jiffies_to_timeval(const unsigned long jiffies,

			       struct timeval *value);

extern clock_t jiffies_to_clock_t(long x);

extern unsigned long clock_t_to_jiffies(unsigned long x);

extern u64 jiffies_64_to_clock_t(u64 x);

extern u64 nsec_to_clock_t(u64 x);

#define TIMESTAMP_SIZE	30

#endif