#include <kernaux/pfa.h>

#include <assert.h>

// Create PFA in some static memory area because typically you don't have memory
// management in kernel without PFA.
struct KernAux_PFA pfa;

int main()
{
    // In the earliest stage of kernel initialization mark all pages as
    // unavailable because you don't have memory map yet.
    KernAux_PFA_initialize(&pfa);

    // Let's assume that you have the following memory map now:
    // * [0 B; 64 KiB)
    // * [1 MiB; 4 MiB)
    // * [6 MiB; 128 MiB)
    // Mark these pages as available. Note that page is identified by any
    // address inside it. This is why you can subtract 1, not only
    // KERNAUX_PFA_PAGE_SIZE.
    KernAux_PFA_mark_available(&pfa, 0,               1024        * 64  - 1);
    KernAux_PFA_mark_available(&pfa, 1024 * 1024,     1024 * 1024 * 4   - 1);
    KernAux_PFA_mark_available(&pfa, 1024 * 1024 * 6, 1024 * 1024 * 128 - 1);

    // You can test page availability.
    assert(KernAux_PFA_is_available(&pfa,  1024 * 32));      // 32 KiB
    assert(!KernAux_PFA_is_available(&pfa, 1024 * 64));      // 64 KiB
    assert(KernAux_PFA_is_available(&pfa,  1024 * 1024));    // 1 MiB
    assert(!KernAux_PFA_is_available(&pfa, 1024 * 1024 * 6   // 6 MiB - 4 KiB
                                           - KERNAUX_PFA_PAGE_SIZE));
    assert(KernAux_PFA_is_available(&pfa,  1024 * 1024 * 128 // 128 MiB - 4 KiB
                                           - KERNAUX_PFA_PAGE_SIZE));
    assert(!KernAux_PFA_is_available(&pfa, 1024 * 1024 * 128)); // 128 MiB

    // When you have configured PFA, you can use it to allocate and free pages.
    const size_t page_addr = KernAux_PFA_alloc_page(&pfa);
    assert(!KernAux_PFA_is_available(&pfa, page_addr));
    KernAux_PFA_free_page(&pfa, page_addr);
    assert(KernAux_PFA_is_available(&pfa, page_addr));

    return 0;
}