#include "kernel/prelude/kernel_prelude.hats"

#define ATS_DYNLOADFLAG 0

staload "./frame.sats"
staload "kernel/bootinfo/multiboot.sats"

staload UN = "prelude/SATS/unsafe.sats"

implement containing_address(address) : frame_t = 
  @{ 
    counter = $UN.cast{size_t}(address) / i2sz(PAGE_SIZE)
  }

fn choose_next_area{l,k : agz}(pf : !frame_allocator_t@l, bf : !boot_info_t @ k | p : ptr l, b : ptr k) : void = let 

in 

end 

implement allocate_frame(pf , bf | p,b) : frame_t = 
  if (p->current_area.length > 1) then  let
      val area = p->current_area
      val frame = @{ num = p->next_free_frame.num }

      // last frame of current area
      val last_frame_area = containing_address(ptr_add<uint8>(area.base_addr,area.length - i2sz(1)))
    in
      if (frame.num > last_frame_area.num) then (
        // all frames of current area are used, switch to next area
        choose_next_area(pf, bf | p,b);
        allocate_frame(pf,bf | p,b)
      ) else if (frame.num > p->kernel_start.num && frame.num <= p->kernel_end.num) then (
        // frame is used by kernel
        p->next_free_frame := @{num = p->kernel_end.num + 1};
        allocate_frame(pf,bf | p,b)
      ) else if (frame.num > p->multiboot_start.num && frame.num <= p->multiboot_end.num) then (
        // frame is used by multiboot info structure
        p->next_free_frame := @{num = p->multiboot_end.num + 1};
        allocate_frame(pf,bf | p,b)
      ) else (
        // frame is unused, increment `next_free_frame` and return it
        p->next_free_frame.num := succ(p->next_free_frame.num);
        frame
      );
    end
  else
    @{num = i2sz(0)} // No free frames left
    


implement deallocate_frame(p) : void = let

in
 
end