Subversion Repositories planix.SVN

#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*)&order;
        for(i = 0; i < sizeof order; i++)
                t[o[i]] = f[i];
}

static int fd = -1;
static struct {
        int     pid;
        int     fd;
} fds[64];

vlong
nsec(void)
{
        uchar b[8];
        vlong t;
        int pid, i, f, tries;

        /*
         * Threaded programs may have multiple procs
         * with different fd tables, so we may need to open
         * /dev/bintime on a per-pid basis
         */

        /* First, look if we've opened it for this particular pid */
        if((pid = _tos->pid) == 0)              /* 9vx bug, perhaps? */
                _tos->pid = pid = getpid();
        do{
                f = -1;
                for(i = 0; i < nelem(fds); i++)
                        if(fds[i].pid == pid){
                                f = fds[i].fd;
                                break;
                        }
                tries = 0;
                if(f < 0){
                        /* If it's not open for this pid, try the global pid */
                        if(fd >= 0)
                                f = fd;
                        else{
                                /* must open */
                                if((f = open("/dev/bintime", OREAD|OCEXEC)) < 0)
                                        return 0;
                                fd = f;
                                for(i = 0; i < nelem(fds); i++)
                                        if(fds[i].pid == pid || fds[i].pid == 0){
                                                fds[i].pid = pid;
                                                fds[i].fd = f;
                                                break;
                                        }
                        }
                }
                if(pread(f, b, sizeof b, 0) == sizeof b){
                        be2vlong(&t, b);
                        return t;
                }
                close(f);
                if(i < nelem(fds))
                        fds[i].fd = -1;
        }while(tries++ == 0);   /* retry once */
        USED(tries);
        return 0;
}