shithub: npe

ref: ac5e2726dfed47e8aec9ca165323c26bdbc9d926
dir: /libnpe/_plan9.c/

#include "plan9.h"
#include <tos.h>

enum {
	Nsec = 1000000000ULL,
};

/*
 * nsec() is wallclock and can be adjusted by timesync
 * so need to use cycles() instead, but fall back to
 * nsec() in case we can't
 */
uvlong
npe_nanosec(void)
{
	static uvlong fasthz, xstart;
	uvlong x, div;

	if(fasthz == ~0ULL)
		return nsec() - xstart;

	if(fasthz == 0){
		if(_tos->cyclefreq){
			cycles(&xstart);
			fasthz = _tos->cyclefreq;
		} else {
			xstart = nsec();
			fasthz = ~0ULL;
			fprint(2, "cyclefreq not available, falling back to nsec()\n");
			fprint(2, "you might want to disable aux/timesync\n");
			return 0;
		}
	}
	cycles(&x);
	x -= xstart;

	/* this is ugly */
	for(div = Nsec; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

	return x / (fasthz / div);
}

void
npe_nsleep(uvlong ns)
{
	uvlong start, end;

	start = npe_nanosec();
	end = start + ns;
	ns = start;
	do{
		if(end - ns > 750000000ULL)
			sleep(70);
		else if (end - ns > 25000000ULL)
			sleep(20);
		else if (end - ns > 10000000ULL)
			sleep(1);
		else
			break;
		ns = npe_nanosec();
	}while(ns < end);
}