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//! Create Kagami
const common = @import("../../../common/common.zig");
const pmm = @import("../../pmm/pmm.zig");
const types = @import("../types/types.zig");
const state = @import("../state.zig");
const tables = @import("../tables/tables.zig");
const AllocationError = common.errors.memory.AllocationError;
const Kagami = types.Kagami;
const Table = types.Table;
var kagami_pool: [256]Kagami = undefined;
var kagami_pool_bitmap: [32]u8 = [_]u8{0} ** 32;
pub fn create() AllocationError!*Kagami {
const pml4_physical = try pmm.allocate_page_zeroed();
const kagami = allocate_kagami_struct() orelse {
pmm.free_page(pml4_physical);
return AllocationError.OutOfMemory;
};
kagami.* = Kagami{
.pml4_physical = pml4_physical,
.reference_count = 1,
.resident_pages = 0,
.wired_pages = 0,
.table_pages = 1,
.lock = false,
};
const kernel_kagami = state.get_kernel_kagami();
const new_pml4 = tables.get_pml4(pml4_physical);
const kernel_pml4 = tables.get_pml4(kernel_kagami.pml4_physical);
new_pml4.copy_kernel_entries(kernel_pml4);
return kagami;
}
fn allocate_kagami_struct() ?*Kagami {
var index: usize = 0;
while (index < 256) : (index += 1) {
const byte_index = index / 8;
const bit_index: u3 = @truncate(index % 8);
if ((kagami_pool_bitmap[byte_index] & (@as(u8, 1) << bit_index)) == 0) {
kagami_pool_bitmap[byte_index] |= (@as(u8, 1) << bit_index);
return &kagami_pool[index];
}
}
return null;
}
pub fn free_kagami_struct(kagami: *Kagami) void {
const base_ptr: usize = @intFromPtr(&kagami_pool[0]);
const kagami_ptr: usize = @intFromPtr(kagami);
if (kagami_ptr < base_ptr) return;
const offset = kagami_ptr - base_ptr;
const index = offset / @sizeOf(Kagami);
if (index >= 256) return;
const byte_index = index / 8;
const bit_index: u3 = @truncate(index % 8);
kagami_pool_bitmap[byte_index] &= ~(@as(u8, 1) << bit_index);
}
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