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#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
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