#ifndef _LINUX_TIME_H
#define _LINUX_TIME_H
+#include <asm/param.h>
#include <linux/types.h>
-#ifdef __KERNEL__
-#include <linux/seqlock.h>
-#endif
-
#ifndef _STRUCT_TIMESPEC
#define _STRUCT_TIMESPEC
struct timespec {
#ifdef __KERNEL__
+#include <linux/spinlock.h>
+#include <linux/seqlock.h>
+#include <linux/timex.h>
+#include <asm/div64.h>
+#ifndef div_long_long_rem
+
+#define div_long_long_rem(dividend,divisor,remainder) ({ \
+ u64 result = dividend; \
+ *remainder = do_div(result,divisor); \
+ result; })
+
+#endif
+
+/*
+ * Have the 32 bit jiffies value wrap 5 minutes after boot
+ * so jiffies wrap bugs show up earlier.
+ */
+#define INITIAL_JIFFIES ((unsigned long)(0))
+
+/*
+ * Change timeval to jiffies, trying to avoid the
+ * most obvious overflows..
+ *
+ * And some not so obvious.
+ *
+ * Note that we don't want to return MAX_LONG, 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 ((~0UL >> 1)-1)
+
/* Parameters used to convert the timespec values */
#ifndef USEC_PER_SEC
#define USEC_PER_SEC (1000000L)
#define NSEC_PER_USEC (1000L)
#endif
+/*
+ * 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 used 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 take 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 jiffies to milliseconds and back.
+ *
+ * Avoid unnecessary multiplications/divisions in the
+ * two most common HZ cases:
+ */
+static inline unsigned int jiffies_to_msecs(const unsigned long j)
+{
+#if HZ <= 1000 && !(1000 % HZ)
+ return (1000 / HZ) * j;
+#elif HZ > 1000 && !(HZ % 1000)
+ return (j + (HZ / 1000) - 1)/(HZ / 1000);
+#else
+ return (j * 1000) / HZ;
+#endif
+}
+
+static inline unsigned int jiffies_to_usecs(const unsigned long j)
+{
+#if HZ <= 1000 && !(1000 % HZ)
+ return (1000000 / HZ) * j;
+#elif HZ > 1000 && !(HZ % 1000)
+ return (j*1000 + (HZ - 1000))/(HZ / 1000);
+#else
+ return (j * 1000000) / HZ;
+#endif
+}
+
+static inline unsigned long msecs_to_jiffies(const unsigned int m)
+{
+ if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
+ return MAX_JIFFY_OFFSET;
+#if HZ <= 1000 && !(1000 % HZ)
+ return (m + (1000 / HZ) - 1) / (1000 / HZ);
+#elif HZ > 1000 && !(HZ % 1000)
+ return m * (HZ / 1000);
+#else
+ return (m * HZ + 999) / 1000;
+#endif
+}
+
+/*
+ * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
+ * that a remainder subtract here would not do the right thing as the
+ * resolution values don't fall on second boundries. I.e. the line:
+ * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
+ *
+ * Rather, we just shift the bits off the right.
+ *
+ * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
+ * value to a scaled second value.
+ */
+static __inline__ unsigned long
+timespec_to_jiffies(const struct timespec *value)
+{
+ unsigned long sec = value->tv_sec;
+ long nsec = value->tv_nsec + TICK_NSEC - 1;
+
+ if (sec >= MAX_SEC_IN_JIFFIES){
+ sec = MAX_SEC_IN_JIFFIES;
+ nsec = 0;
+ }
+ return (((u64)sec * SEC_CONVERSION) +
+ (((u64)nsec * NSEC_CONVERSION) >>
+ (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
+
+}
+
+static __inline__ void
+jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
+{
+ /*
+ * Convert jiffies to nanoseconds and separate with
+ * one divide.
+ */
+ u64 nsec = (u64)jiffies * TICK_NSEC;
+ value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec);
+}
+
+/* Same for "timeval"
+ *
+ * Well, almost. The problem here is that the real system resolution is
+ * in nanoseconds and the value being converted is in micro seconds.
+ * Also for some machines (those that use HZ = 1024, in-particular),
+ * there is a LARGE error in the tick size in microseconds.
+
+ * The solution we use is to do the rounding AFTER we convert the
+ * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
+ * Instruction wise, this should cost only an additional add with carry
+ * instruction above the way it was done above.
+ */
+static __inline__ unsigned long
+timeval_to_jiffies(const struct timeval *value)
+{
+ unsigned long sec = value->tv_sec;
+ long usec = value->tv_usec;
+
+ if (sec >= MAX_SEC_IN_JIFFIES){
+ sec = MAX_SEC_IN_JIFFIES;
+ usec = 0;
+ }
+ return (((u64)sec * SEC_CONVERSION) +
+ (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
+ (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
+}
+
+static __inline__ void
+jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
+{
+ /*
+ * Convert jiffies to nanoseconds and separate with
+ * one divide.
+ */
+ u64 nsec = (u64)jiffies * TICK_NSEC;
+ value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_usec);
+ value->tv_usec /= NSEC_PER_USEC;
+}
+
static __inline__ int timespec_equal(struct timespec *a, struct timespec *b)
{
return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
#define CURRENT_TIME (current_kernel_time())
+#endif /* __KERNEL__ */
+
+#define NFDBITS __NFDBITS
+
+#ifdef __KERNEL__
extern void do_gettimeofday(struct timeval *tv);
extern int do_settimeofday(struct timespec *tv);
extern int do_sys_settimeofday(struct timespec *tv, struct timezone *tz);
ts->tv_sec = sec;
ts->tv_nsec = nsec;
}
-
-#endif /* __KERNEL__ */
-
-#define NFDBITS __NFDBITS
+#endif
#define FD_SETSIZE __FD_SETSIZE
#define FD_SET(fd,fdsetp) __FD_SET(fd,fdsetp)
#define CLOCK_REALTIME_HR 4
#define CLOCK_MONOTONIC_HR 5
-/*
- * The IDs of various hardware clocks
- */
-
-
-#define CLOCK_SGI_CYCLE 10
-#define MAX_CLOCKS 16
+#define MAX_CLOCKS 6
#define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC | \
CLOCK_REALTIME_HR | CLOCK_MONOTONIC_HR)
#define CLOCKS_MONO (CLOCK_MONOTONIC & CLOCK_MONOTONIC_HR)
git://git.onelab.eu / linux-2.6.git / blobdiff