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- #include <u.h>
- #include <libc.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 < 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.
- */
- vlong
- nsec(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;
- }
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