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plan 9: simpler and more precise(?) nanosec_monotonic

--- a/src/plan9/sys.c

+++ b/src/plan9/sys.c

@@ -2,14 +2,16 @@

 #include "timefuncs.h"

 #include <tos.h>

+#define Nsec 1000000000ULL

+

 double D_PNAN, D_PINF;

 double

 sec_realtime(void)

 {

-	vlong t = nsec();

-	vlong ns = t % 1000000000LL;

-	vlong s = (t - ns) / 1000000000LL;

+	uvlong t = nsec();

+	uvlong ns = t % Nsec;

+	uvlong s = (t - ns) / Nsec;

 	return (double)s + (double)ns/1.0e9;

 }

@@ -18,11 +20,11 @@

  * so need to use cycles() instead, but fall back to

  * nsec() in case we can't

  */

-uint64_t

+u64int

 nanosec_monotonic(void)

 {

-	static uint64_t fasthz, xstart;

-	uint64_t x, div;

+	static u64int fasthz, xstart;

+	u64int x;

 	if(fasthz == ~0ULL)

 		return nsec() - xstart;

@@ -40,10 +42,10 @@

 	cycles(&x);

 	x -= xstart;

-	/* this is ugly */

-	for(div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

+	u64int q = x / fasthz;

+	u64int r = x % fasthz;

-	return x / (fasthz / div);

+	return q*Nsec + r*Nsec/fasthz;

 }

 void