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// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "common/alignment.h"
#include "core/file_sys/fssystem/fssystem_alignment_matching_storage_impl.h"
namespace FileSys {
namespace {
template <typename T>
constexpr size_t GetRoundDownDifference(T x, size_t align) {
return static_cast<size_t>(x - Common::AlignDown(x, align));
}
template <typename T>
constexpr size_t GetRoundUpDifference(T x, size_t align) {
return static_cast<size_t>(Common::AlignUp(x, align) - x);
}
template <typename T>
size_t GetRoundUpDifference(T* x, size_t align) {
return GetRoundUpDifference(reinterpret_cast<uintptr_t>(x), align);
}
} // namespace
size_t AlignmentMatchingStorageImpl::Read(VirtualFile base_storage, char* work_buf,
size_t work_buf_size, size_t data_alignment,
size_t buffer_alignment, s64 offset, u8* buffer,
size_t size) {
// Check preconditions.
ASSERT(work_buf_size >= data_alignment);
// Succeed if zero size.
if (size == 0) {
return size;
}
// Validate arguments.
ASSERT(buffer != nullptr);
// Determine extents.
u8* aligned_core_buffer;
s64 core_offset;
size_t core_size;
size_t buffer_gap;
size_t offset_gap;
s64 covered_offset;
const size_t offset_round_up_difference = GetRoundUpDifference(offset, data_alignment);
if (Common::IsAligned(reinterpret_cast<uintptr_t>(buffer) + offset_round_up_difference,
buffer_alignment)) {
aligned_core_buffer = buffer + offset_round_up_difference;
core_offset = Common::AlignUp(offset, data_alignment);
core_size = (size < offset_round_up_difference)
? 0
: Common::AlignDown(size - offset_round_up_difference, data_alignment);
buffer_gap = 0;
offset_gap = 0;
covered_offset = core_size > 0 ? core_offset : offset;
} else {
const size_t buffer_round_up_difference = GetRoundUpDifference(buffer, buffer_alignment);
aligned_core_buffer = buffer + buffer_round_up_difference;
core_offset = Common::AlignDown(offset, data_alignment);
core_size = (size < buffer_round_up_difference)
? 0
: Common::AlignDown(size - buffer_round_up_difference, data_alignment);
buffer_gap = buffer_round_up_difference;
offset_gap = GetRoundDownDifference(offset, data_alignment);
covered_offset = offset;
}
// Read the core portion.
if (core_size > 0) {
base_storage->Read(aligned_core_buffer, core_size, core_offset);
if (offset_gap != 0 || buffer_gap != 0) {
std::memmove(aligned_core_buffer - buffer_gap, aligned_core_buffer + offset_gap,
core_size - offset_gap);
core_size -= offset_gap;
}
}
// Handle the head portion.
if (offset < covered_offset) {
const s64 head_offset = Common::AlignDown(offset, data_alignment);
const size_t head_size = static_cast<size_t>(covered_offset - offset);
ASSERT(GetRoundDownDifference(offset, data_alignment) + head_size <= work_buf_size);
base_storage->Read(reinterpret_cast<u8*>(work_buf), data_alignment, head_offset);
std::memcpy(buffer, work_buf + GetRoundDownDifference(offset, data_alignment), head_size);
}
// Handle the tail portion.
s64 tail_offset = covered_offset + core_size;
size_t remaining_tail_size = static_cast<size_t>((offset + size) - tail_offset);
while (remaining_tail_size > 0) {
const auto aligned_tail_offset = Common::AlignDown(tail_offset, data_alignment);
const auto cur_size =
std::min(static_cast<size_t>(aligned_tail_offset + data_alignment - tail_offset),
remaining_tail_size);
base_storage->Read(reinterpret_cast<u8*>(work_buf), data_alignment, aligned_tail_offset);
ASSERT((tail_offset - offset) + cur_size <= size);
ASSERT((tail_offset - aligned_tail_offset) + cur_size <= data_alignment);
std::memcpy(reinterpret_cast<char*>(buffer) + (tail_offset - offset),
work_buf + (tail_offset - aligned_tail_offset), cur_size);
remaining_tail_size -= cur_size;
tail_offset += cur_size;
}
return size;
}
size_t AlignmentMatchingStorageImpl::Write(VirtualFile base_storage, char* work_buf,
size_t work_buf_size, size_t data_alignment,
size_t buffer_alignment, s64 offset, const u8* buffer,
size_t size) {
// Check preconditions.
ASSERT(work_buf_size >= data_alignment);
// Succeed if zero size.
if (size == 0) {
return size;
}
// Validate arguments.
ASSERT(buffer != nullptr);
// Determine extents.
const u8* aligned_core_buffer;
s64 core_offset;
size_t core_size;
s64 covered_offset;
const size_t offset_round_up_difference = GetRoundUpDifference(offset, data_alignment);
if (Common::IsAligned(reinterpret_cast<uintptr_t>(buffer) + offset_round_up_difference,
buffer_alignment)) {
aligned_core_buffer = buffer + offset_round_up_difference;
core_offset = Common::AlignUp(offset, data_alignment);
core_size = (size < offset_round_up_difference)
? 0
: Common::AlignDown(size - offset_round_up_difference, data_alignment);
covered_offset = core_size > 0 ? core_offset : offset;
} else {
aligned_core_buffer = nullptr;
core_offset = Common::AlignDown(offset, data_alignment);
core_size = 0;
covered_offset = offset;
}
// Write the core portion.
if (core_size > 0) {
base_storage->Write(aligned_core_buffer, core_size, core_offset);
}
// Handle the head portion.
if (offset < covered_offset) {
const s64 head_offset = Common::AlignDown(offset, data_alignment);
const size_t head_size = static_cast<size_t>(covered_offset - offset);
ASSERT((offset - head_offset) + head_size <= data_alignment);
base_storage->Read(reinterpret_cast<u8*>(work_buf), data_alignment, head_offset);
std::memcpy(work_buf + (offset - head_offset), buffer, head_size);
base_storage->Write(reinterpret_cast<u8*>(work_buf), data_alignment, head_offset);
}
// Handle the tail portion.
s64 tail_offset = covered_offset + core_size;
size_t remaining_tail_size = static_cast<size_t>((offset + size) - tail_offset);
while (remaining_tail_size > 0) {
ASSERT(static_cast<size_t>(tail_offset - offset) < size);
const auto aligned_tail_offset = Common::AlignDown(tail_offset, data_alignment);
const auto cur_size =
std::min(static_cast<size_t>(aligned_tail_offset + data_alignment - tail_offset),
remaining_tail_size);
base_storage->Read(reinterpret_cast<u8*>(work_buf), data_alignment, aligned_tail_offset);
std::memcpy(work_buf + GetRoundDownDifference(tail_offset, data_alignment),
buffer + (tail_offset - offset), cur_size);
base_storage->Write(reinterpret_cast<u8*>(work_buf), data_alignment, aligned_tail_offset);
remaining_tail_size -= cur_size;
tail_offset += cur_size;
}
return size;
}
} // namespace FileSys
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