[client] implemented better clock drift correction

common/include/common/time.h

@@ -66,6 +66,42 @@ static inline void nsleep(uint64_t ns)
   };
   nanosleep(&ts, NULL);
 }
+
+static inline void tsDiff(struct timespec *diff, const struct timespec *left,
+              const struct timespec *right)
+{
+  diff->tv_sec = left->tv_sec - right->tv_sec;
+  diff->tv_nsec = left->tv_nsec - right->tv_nsec;
+  if (diff->tv_nsec < 0)
+  {
+    --diff->tv_sec;
+    diff->tv_nsec += 1000000000;
+  }
+}
+
+static inline uint32_t __iter_div_u64_rem(uint64_t dividend, uint32_t divisor, uint64_t *remainder)
+{
+  uint32_t ret = 0;
+
+  while (dividend >= divisor) {
+    /* The following asm() prevents the compiler from
+       optimising this loop into a modulo operation.  */
+    asm("" : "+rm"(dividend));
+
+    dividend -= divisor;
+    ret++;
+  }
+
+  *remainder = dividend;
+
+  return ret;
+}
+
+static inline void tsAdd(struct timespec *a, uint64_t ns)
+{
+  a->tv_sec  += __iter_div_u64_rem(a->tv_nsec + ns, 1000000000L, &ns);
+  a->tv_nsec = ns;
+}
 #endif
 
 typedef bool (*LGTimerFn)(void * udata);