// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-3.0-or-later
#pragma once
#include "common/alignment.h"
#include "common/common_types.h"
namespace VideoCommon {
class UsageTracker {
static constexpr size_t BYTES_PER_BIT_SHIFT = 6;
static constexpr size_t PAGE_SHIFT = 6 + BYTES_PER_BIT_SHIFT;
static constexpr size_t PAGE_BYTES = 1 << PAGE_SHIFT;
public:
explicit UsageTracker(size_t size) {
const size_t num_pages = (size >> PAGE_SHIFT) + 1;
pages.resize(num_pages, 0ULL);
}
void Reset() noexcept {
std::ranges::fill(pages, 0ULL);
}
void Track(u64 offset, u64 size) noexcept {
const size_t page = offset >> PAGE_SHIFT;
const size_t page_end = (offset + size) >> PAGE_SHIFT;
if (page_end < page || page_end >= pages.size()) {
return;
}
TrackPage(page, offset, size);
if (page == page_end) {
return;
}
for (size_t i = page + 1; i < page_end; i++) {
pages[i] = ~u64{0};
}
const size_t offset_end = offset + size;
const size_t offset_end_page_aligned = Common::AlignDown(offset_end, PAGE_BYTES);
TrackPage(page_end, offset_end_page_aligned, offset_end - offset_end_page_aligned);
}
[[nodiscard]] bool IsUsed(u64 offset, u64 size) const noexcept {
const size_t page = offset >> PAGE_SHIFT;
const size_t page_end = (offset + size) >> PAGE_SHIFT;
if (page_end < page || page_end >= pages.size()) {
return false;
}
if (IsPageUsed(page, offset, size)) {
return true;
}
for (size_t i = page + 1; i < page_end; i++) {
if (pages[i] != 0) {
return true;
}
}
const size_t offset_end = offset + size;
const size_t offset_end_page_aligned = Common::AlignDown(offset_end, PAGE_BYTES);
return IsPageUsed(page_end, offset_end_page_aligned, offset_end - offset_end_page_aligned);
}
private:
void TrackPage(u64 page, u64 offset, u64 size) noexcept {
const size_t offset_in_page = offset % PAGE_BYTES;
const size_t first_bit = offset_in_page >> BYTES_PER_BIT_SHIFT;
const size_t num_bits = std::min<size_t>(size, PAGE_BYTES) >> BYTES_PER_BIT_SHIFT;
const size_t mask = ~u64{0} >> (64 - num_bits);
pages[page] |= (~u64{0} & mask) << first_bit;
}
bool IsPageUsed(u64 page, u64 offset, u64 size) const noexcept {
const size_t offset_in_page = offset % PAGE_BYTES;
const size_t first_bit = offset_in_page >> BYTES_PER_BIT_SHIFT;
const size_t num_bits = std::min<size_t>(size, PAGE_BYTES) >> BYTES_PER_BIT_SHIFT;
const size_t mask = ~u64{0} >> (64 - num_bits);
const size_t mask2 = (~u64{0} & mask) << first_bit;
return (pages[page] & mask2) != 0;
}
private:
std::vector<u64> pages;
};
} // namespace VideoCommon
