timecounting: add FRAC_TO_NSEC(), BINTIME_TO_NSEC()

Refactor the fraction-to-nanosecond conversion from BINTIME_TO_TIMESPEC()
into a dedicated routine, FRAC_TO_NSEC(), so we can reuse it elsewhere.

Then add a new BINTIME_TO_NSEC() function to sys/time.h to deduplicate
conversion code in nsecuptime(), getnsecuptime(), and tc_setclock().

Thread: https://marc.info/?l=openbsd-tech&m=162376993926751&w=2

ok dlg@

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index f56ed18..69a4a3b 100644 (file)
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_tc.c,v 1.73 2021/06/15 05:24:46 dlg Exp $ */
+/*     $OpenBSD: kern_tc.c,v 1.74 2021/06/19 13:49:39 cheloha Exp $ */
 
 /*
  * Copyright (c) 2000 Poul-Henning Kamp <phk@FreeBSD.org>
@@ -254,28 +254,18 @@ uint64_t
 nsecuptime(void)
 {
        struct bintime bt;
-       uint64_t nsec;
 
        binuptime(&bt);
-
-       nsec = (1000000000ULL * (bt.frac >> 32)) >> 32;
-       nsec += bt.sec * 1000000000ULL;
-
-       return (nsec);
+       return BINTIME_TO_NSEC(&bt);
 }
 
 uint64_t
 getnsecuptime(void)
 {
        struct bintime bt;
-       uint64_t nsec;
 
        getbinuptime(&bt);
-
-       nsec = (1000000000ULL * (bt.frac >> 32)) >> 32;
-       nsec += bt.sec * 1000000000ULL;
-
-       return (nsec);
+       return BINTIME_TO_NSEC(&bt);
 }
 
 void
@@ -567,8 +557,7 @@ tc_setclock(const struct timespec *ts)
 #ifndef SMALL_KERNEL
        /* convert the bintime to ticks */
        bintimesub(&new_naptime, &old_naptime, &elapsed);
-       adj_ticks = (uint64_t)hz * elapsed.sec +
-           (((uint64_t)1000000 * (uint32_t)(elapsed.frac >> 32)) >> 32) / tick;
+       adj_ticks = BINTIME_TO_NSEC(&elapsed) / tick_nsec;
        if (adj_ticks > 0) {
                if (adj_ticks > INT_MAX)
                        adj_ticks = INT_MAX;

diff --git a/sys/sys/time.h b/sys/sys/time.h
index 7f1b016..ac0eb2f 100644 (file)
--- a/sys/sys/time.h
+++ b/sys/sys/time.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: time.h,v 1.60 2021/06/15 05:24:47 dlg Exp $   */
+/*     $OpenBSD: time.h,v 1.61 2021/06/19 13:49:39 cheloha Exp $       */
 /*     $NetBSD: time.h,v 1.18 1996/04/23 10:29:33 mycroft Exp $        */
 
 /*
@@ -222,11 +222,17 @@ bintimesub(const struct bintime *bt, const struct bintime *ct,
  *   time_second ticks after N.999999999 not after N.4999999999
  */
 
+static inline uint32_t
+FRAC_TO_NSEC(uint64_t frac)
+{
+       return ((frac >> 32) * 1000000000ULL) >> 32;
+}
+
 static inline void
 BINTIME_TO_TIMESPEC(const struct bintime *bt, struct timespec *ts)
 {
        ts->tv_sec = bt->sec;
-       ts->tv_nsec = (long)(((uint64_t)1000000000 * (uint32_t)(bt->frac >> 32)) >> 32);
+       ts->tv_nsec = FRAC_TO_NSEC(bt->frac);
 }
 
 static inline void
@@ -412,6 +418,12 @@ TIMESPEC_TO_NSEC(const struct timespec *ts)
        return ts->tv_sec * 1000000000ULL + ts->tv_nsec;
 }
 
+static inline uint64_t
+BINTIME_TO_NSEC(const struct bintime *bt)
+{
+       return bt->sec * 1000000000ULL + FRAC_TO_NSEC(bt->frac);
+}
+
 #else /* !_KERNEL */
 #include <time.h>