+/*
+ * lfsr_next does the following:
+ *
+ * a. Return if the number of max values has been exceeded.
+ * b. Check if we have a spin value that produces a repeating subsequence.
+ * This is previously calculated in `prepare_spin` and cycle_length should
+ * be > 0. If we do have such a spin:
+ *
+ * i. Decrement the calculated cycle.
+ * ii. If it reaches zero, add "+1" to the spin and reset the cycle_length
+ * (we have it cached in the struct fio_lfsr)
+ *
+ * In either case, continue with the calculation of the next value.
+ * c. Check if the calculated value exceeds the desirable range. In this case,
+ * go back to b, else return.
+ */
+int lfsr_next(struct fio_lfsr *fl, uint64_t *off)