Atmosphere/libraries/libmesosphere/include/mesosphere/kern_k_page_heap.hpp
2020-01-30 15:29:51 -08:00

61 lines
2.8 KiB
C++

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <mesosphere/kern_common.hpp>
namespace ams::kern {
class KPageHeap {
private:
class Block {
private:
class Bitmap {
/* TODO: This is a four-level bitmap tracking page usage. */
private:
static constexpr s32 GetRequiredDepth(size_t region_size) {
s32 depth = 0;
while (true) {
region_size /= BITSIZEOF(u64);
depth++;
if (region_size == 0) {
return depth;
}
}
}
public:
static constexpr size_t CalculateMetadataOverheadSize(size_t region_size) {
size_t overhead_bits = 0;
for (s32 depth = GetRequiredDepth(region_size) - 1; depth >= 0; depth--) {
region_size = util::AlignUp(region_size, BITSIZEOF(u64)) / BITSIZEOF(u64);
overhead_bits += region_size;
}
return overhead_bits * sizeof(u64);
}
};
public:
static constexpr size_t CalculateMetadataOverheadSize(size_t region_size, size_t cur_block_shift, size_t next_block_shift) {
const size_t cur_block_size = (1ul << cur_block_shift);
const size_t next_block_size = (1ul << next_block_shift);
const size_t align = (next_block_shift != 0) ? next_block_size : cur_block_size;
return Bitmap::CalculateMetadataOverheadSize((align * 2 + util::AlignUp(region_size, align)) / cur_block_size);
}
};
public:
static size_t CalculateMetadataOverheadSize(size_t region_size, const size_t *block_shifts, size_t num_block_shifts);
};
}