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#include <u.h>
#include <libc.h>
#include <tos.h>
static uvlong order = 0x0001020304050607ULL;
static void
be2vlong(vlong *to, uchar *f)
{
uchar *t, *o;
int i;
t = (uchar*)to;
o = (uchar*)ℴ
for(i = 0; i < sizeof order; i++)
t[o[i]] = f[i];
}
static int
stillopen(int fd, char *name)
{
char buf[64];
return fd >= 0 && fd2path(fd, buf, sizeof(buf)) == 0 && strcmp(buf, name) == 0;
}
vlong
nsec(void)
{
static char name[] = "/dev/bintime";
static int *pidp = nil, *fdp = nil, fd = -1;
uchar b[8];
vlong t;
int f;
if(pidp != nil && *pidp == _tos->pid)
f = *fdp;
else{
Reopen:
f = fd;
if(fdp != nil && *fdp != f && stillopen(*fdp, name))
f = *fdp;
else if(!stillopen(f, name)){
if((f = open(name, OREAD|OCEXEC)) < 0)
return 0;
}
fd = f;
if(fdp == nil){
fdp = (int*)privalloc();
pidp = (int*)privalloc();
}
*fdp = f;
*pidp = _tos->pid;
}
if(pread(f, b, sizeof b, 0) != sizeof b){
if(!stillopen(f, name))
goto Reopen;
close(f);
return 0;
}
be2vlong(&t, b);
return t;
}
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