/*
* 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)
{
if (fl->num_vals++ > fl->max_val)
return 1;
do {
if (fl->cycle_length && !--fl->cycle_length) {
__lfsr_next(fl, fl->spin + 1);
fl->cycle_length = fl->cached_cycle_length;
} else
__lfsr_next(fl, fl->spin);
} while (fio_unlikely(fl->last_val > fl->max_val));
*off = fl->last_val;
return 0;
}
/*
* 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, uint64_t last)
{
if (fl->num_vals++ > fl->max_val)
return 1;
do {
if (fl->cycle_length && !--fl->cycle_length) {
__lfsr_next(fl, fl->spin + 1);
fl->cycle_length = fl->cached_cycle_length;
goto check;
}
__lfsr_next(fl, fl->spin);
check:
;
} while (fl->last_val > fl->max_val);
*off = fl->last_val;
return 0;
}
/*
* 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.
*/
uint64_t lfsr_next(struct bench_lfsr *lfsr)
{
lfsr->num_vals++;
do {
if (lfsr->cycle_length) {
lfsr->cycle_length--;
if (!lfsr->cycle_length) {
__lfsr_next(lfsr, lfsr->spin + 1);
lfsr->cycle_length = lfsr->cached_cycle_length;
goto check;
}
}
__lfsr_next(lfsr, lfsr->spin);
check: ;
} while (lfsr->last_val > lfsr->max_val);
return lfsr->last_val;
}
