/** Add 'n' bytes to the number of bytes in b for second 'when'.
*/
static INLINE void add_obs(bw_array_t *b, time_t when, int n) {
- /* If we're currently adding observations for an earlier second than 'when',
- * advance 'when' by an appropriate number of seconds. */
- while (when<b->cur_obs_time)
+ /* Don't record data in the past. */
+ if (when<b->cur_obs_time)
+ return;
+ /* If we're currently adding observations for an earlier second than
+ * 'when', advance b->cur_obs_time and b->cur_obs_idx by an
+ * appropriate number of seconds, and do all the other housekeeping */
+ while (when>b->cur_obs_time)
advance_obs(b);
+
b->obs[b->cur_obs_idx] += n;
}