#include <u.h>#include <libc.h> static uvlong order = (uvlong) 0x0001020304050607ULL; static voidbe2vlong(vlong *to, uchar *f){	uchar *t, *o;	int i; 	t = (uchar*)to;	o = (uchar*)&order;	for(i = 0; i < 8; i++)		t[o[i]] = f[i];} /* *  After a fork with fd's copied, both fd's are pointing to *  the same Chan structure.  Since the offset is kept in the Chan *  structure, the seek's and read's in the two processes can *  compete at moving the offset around.  Hence the retry loop. * *  Since the bintime version doesn't need a seek, it doesn't *  have the loop. */vlongnsec(void){	char b[12+1];	static int f = -1;	static int usebintime;	int retries;	vlong t; 	if(f < 0){		usebintime = 1;		f = open("/dev/bintime", OREAD|OCEXEC);		if(f < 0){			usebintime = 0;			f = open("/dev/nsec", OREAD|OCEXEC);			if(f < 0)				return 0;		}	} 	if(usebintime){		if(read(f, b, sizeof(uvlong)) < 0)			goto error;		be2vlong(&t, (uchar*)b);		return t;	} else {		for(retries = 0; retries < 100; retries++){			if(seek(f, 0, 0) >= 0 && read(f, b, sizeof(b)-1) >= 0){				b[sizeof(b)-1] = 0;				return strtoll(b, 0, 0);			}		}	} error:	close(f);	f = -1;	return 0;}