Add static version of queue

[daveythacher]

I was looking into the queue API and I noticed that it works off the heap. It should be possible to implement this as static?

pico-sdk/src/common/pico_util/queue.c

Lines 11 to 18 in 6a7db34

	void queue_init_with_spinlock(queue_t *q, uint element_size, uint element_count, uint spinlock_num) {
	lock_init(&q->core, spinlock_num);
	q->data = (uint8_t *)calloc(element_count + 1, element_size);
	q->element_count = (uint16_t)element_count;
	q->element_size = (uint16_t)element_size;
	q->wptr = 0;
	q->rptr = 0;
	}

It is a little more risky, but for people that do not want to use heap they are probably stuck with that.

void static_queue_init_with_spinlock(queue_t *q, uint element_size, uint element_count, uint spinlock_num, uint8_t *storage) {
    lock_init(&q->core, spinlock_num);
    q->data = storage;
    q->element_count = (uint16_t)element_count;
    q->element_size = (uint16_t)element_size;
    q->wptr = 0;
    q->rptr = 0;
}

[peterharperuk]

Yes, that would be good

[lurch]

In your proposed new function, it might also be worth passing in a storage_size parameter, and then asserting that storage_size >= ((element_count + 1) * element_size) ?

[daveythacher]

Forgot about the assert. I had considered it but did not see the point in changing the return signature. (We can be mislead.)

Note there is no nullptr check.