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#ifndef _LINUX_JIFFIES_H |
#define _LINUX_JIFFIES_H |
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//#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 */ |
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#define HZ 100 |
#define CLOCK_TICK_RATE 1193182ul |
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/* |
* 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 |
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/* LATCH is used in the interval timer and ftape setup. */ |
#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ |
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/* Suppose we want to divide 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)) |
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/* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */ |
#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8)) |
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/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */ |
#define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8)) |
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/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ |
#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) |
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/* 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)) |
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#define jiffies GetTimerTicks() |
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#if (BITS_PER_LONG < 64) |
u64 get_jiffies_64(void); |
#else |
static inline u64 get_jiffies_64(void) |
{ |
return (u64)jiffies; |
} |
#endif |
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/* |
* 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) |
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#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) |
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/* |
* Calculate whether a is in the range of [b, c]. |
*/ |
#define time_in_range(a,b,c) \ |
(time_after_eq(a,b) && \ |
time_before_eq(a,c)) |
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/* |
* Calculate whether a is in the range of [b, c). |
*/ |
#define time_in_range_open(a,b,c) \ |
(time_after_eq(a,b) && \ |
time_before(a,c)) |
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/* 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) |
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#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) |
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/* |
* These four macros compare jiffies and 'a' for convenience. |
*/ |
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/* time_is_before_jiffies(a) return true if a is before jiffies */ |
#define time_is_before_jiffies(a) time_after(jiffies, a) |
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/* time_is_after_jiffies(a) return true if a is after jiffies */ |
#define time_is_after_jiffies(a) time_before(jiffies, a) |
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/* 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) |
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/* 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) |
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/* |
* 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)) |
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/* |
* 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) |
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extern unsigned long preset_lpj; |
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/* |
* 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. |
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* 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. |
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* 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). |
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* 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. |
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*/ |
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/* |
* 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. |
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* Limits of cpp (for #if expressions) only long (no long long), but |
* then we only need the most signicant bit. |
*/ |
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#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)) |
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#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) |
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#endif |
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/* |
* 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(unsigned 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); |
extern u64 nsecs_to_jiffies64(u64 n); |
extern unsigned long nsecs_to_jiffies(u64 n); |
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#define TIMESTAMP_SIZE 30 |
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#endif |