#include <socks/vm.h>
#include <socks/memblock.h>
#include <socks/printk.h>

/* array of pages, one for each physical page frame present in RAM */
static vm_page_t *page_array = NULL;

/* number of pages stored in page_array */
static size_t page_array_count = 0;

void vm_flat_init()
{
	printk("vm: using flat memory model");
	size_t pmem_size = 0;

	memblock_iter_t it;
	for_each_free_mem_range (&it, 0x0, UINTPTR_MAX) {
		if (pmem_size < it.it_limit + 1) {
			pmem_size = it.it_limit + 1;
		}
	}

	size_t nr_pages = pmem_size / VM_PAGE_SIZE;
	if (pmem_size % VM_PAGE_SIZE) {
		nr_pages++;
	}

	page_array = memblock_alloc(sizeof(vm_page_t) * nr_pages, 8);
	page_array_count = nr_pages;

	size_t nr_reserved = nr_pages;

	for (size_t i = 0; i < nr_pages; i++) {
		page_array[i].p_flags = VM_PAGE_RESERVED;
	}

	for_each_free_mem_range(&it, 0x0, UINTPTR_MAX) {
		for (uintptr_t i = it.it_base; i < it.it_limit; i += VM_PAGE_SIZE) {
			size_t pfn = i / VM_PAGE_SIZE;

			page_array[pfn].p_flags = 0;
			nr_reserved--;
		}
	}

	printk("vm: page array has %zu pages, %zu reserved", nr_pages, nr_reserved);
}

vm_page_t *vm_page_get_flat(phys_addr_t addr)
{
	size_t pfn = addr / VM_PAGE_SIZE;
	return pfn < page_array_count ? &page_array[pfn] : NULL;
}

size_t vm_page_get_pfn_flat(vm_page_t *pg)
{
	return ((uintptr_t)pg - (uintptr_t)page_array) / sizeof *pg;
}