Function vm_page_bits

freebsd/vm/vm_page.c:4864–4883

* Mapping function for valid or dirty bits in a page. * * Inputs are required to range within a page. */

 * Inputs are required to range within a page.
 */
vm_page_bits_t
vm_page_bits(int base, int size)
{
	int first_bit;
	int last_bit;

	KASSERT(
	    base + size <= PAGE_SIZE,
	    ("vm_page_bits: illegal base/size %d/%d", base, size)
	);

	if (size == 0)		/* handle degenerate case */
		return (0);

	first_bit = base >> DEV_BSHIFT;
	last_bit = (base + size - 1) >> DEV_BSHIFT;

	return (((vm_page_bits_t)2 << last_bit) -
	    ((vm_page_bits_t)1 << first_bit));
}

void
vm_page_bits_set(vm_page_t m, vm_page_bits_t *bits, vm_page_bits_t set)