UefiPoolAllocator

const UefiPoolAllocator = struct

File

Code

const UefiPoolAllocator = struct {
    fn getHeader(ptr: [*]u8) *[*]align(8) u8 {
        return @as(*[*]align(8) u8, @ptrFromInt(@intFromPtr(ptr) - @sizeOf(usize)));
    }

    fn alloc(
        _: *anyopaque,
        len: usize,
        alignment: mem.Alignment,
        ret_addr: usize,
    ) ?[*]u8 {
        _ = ret_addr;

        assert(len > 0);

        const ptr_align = alignment.toByteUnits();

        const metadata_len = mem.alignForward(usize, @sizeOf(usize), ptr_align);

        const full_len = metadata_len + len;

        const unaligned_slice = uefi.system_table.boot_services.?.allocatePool(
            uefi.efi_pool_memory_type,
            full_len,
        ) catch return null;

        const unaligned_addr = @intFromPtr(unaligned_slice.ptr);
        const aligned_addr = mem.alignForward(usize, unaligned_addr + @sizeOf(usize), ptr_align);

        const aligned_ptr = unaligned_slice.ptr + (aligned_addr - unaligned_addr);
        getHeader(aligned_ptr).* = unaligned_slice.ptr;

        return aligned_ptr;
    }

    fn resize(
        _: *anyopaque,
        buf: []u8,
        alignment: mem.Alignment,
        new_len: usize,
        ret_addr: usize,
    ) bool {
        _ = ret_addr;
        _ = alignment;

        if (new_len > buf.len) return false;
        return true;
    }

    fn remap(
        _: *anyopaque,
        buf: []u8,
        alignment: mem.Alignment,
        new_len: usize,
        ret_addr: usize,
    ) ?[*]u8 {
        _ = alignment;
        _ = ret_addr;

        if (new_len > buf.len) return null;
        return buf.ptr;
    }

    fn free(
        _: *anyopaque,
        buf: []u8,
        alignment: mem.Alignment,
        ret_addr: usize,
    ) void {
        _ = alignment;
        _ = ret_addr;
        uefi.system_table.boot_services.?.freePool(getHeader(buf.ptr).*) catch unreachable;
    }
}