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134 lines
3.8 KiB
C++
134 lines
3.8 KiB
C++
// Copyright 2016 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#include <memory>
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#include <string>
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#include <utility>
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#include "Common/CommonFuncs.h"
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#include "Common/FileUtil.h"
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#include "DiscIO/TGCBlob.h"
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namespace
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{
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template <typename T>
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struct Interval
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{
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T start;
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T length;
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T End() const { return start + length; }
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bool IsEmpty() const { return length == 0; }
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};
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template <typename T>
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void SplitInterval(T split_point, Interval<T> interval, Interval<T>* out_1, Interval<T>* out_2)
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{
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if (interval.start < split_point)
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*out_1 = {interval.start, std::min(interval.length, split_point - interval.start)};
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else
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*out_1 = {0, 0};
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if (interval.End() > split_point)
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*out_2 = {std::max(interval.start, split_point),
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std::min(interval.length, interval.End() - split_point)};
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else
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*out_2 = {0, 0};
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}
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u32 SubtractBE32(u32 minuend_be, u32 subtrahend_le)
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{
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return Common::swap32(Common::swap32(minuend_be) - subtrahend_le);
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}
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void Replace8(u64 offset, u64 nbytes, u8* out_ptr, u64 replace_offset, u8 replace_value)
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{
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if (offset <= replace_offset && offset + nbytes > replace_offset)
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out_ptr[replace_offset - offset] = replace_value;
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}
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void Replace32(u64 offset, u64 nbytes, u8* out_ptr, u64 replace_offset, u32 replace_value)
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{
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for (size_t i = 0; i < sizeof(u32); ++i)
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Replace8(offset, nbytes, out_ptr, replace_offset + i, reinterpret_cast<u8*>(&replace_value)[i]);
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}
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}
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namespace DiscIO
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{
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std::unique_ptr<TGCFileReader> TGCFileReader::Create(File::IOFile file)
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{
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TGCHeader header;
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if (file.Seek(0, SEEK_SET) && file.ReadArray(&header, 1) && header.magic == TGC_MAGIC)
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return std::unique_ptr<TGCFileReader>(new TGCFileReader(std::move(file)));
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return nullptr;
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}
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TGCFileReader::TGCFileReader(File::IOFile file) : m_file(std::move(file))
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{
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m_file.Seek(0, SEEK_SET);
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m_file.ReadArray(&m_header, 1);
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u32 header_size = Common::swap32(m_header.header_size);
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m_size = m_file.GetSize();
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m_file_offset = Common::swap32(m_header.unknown_important_2) -
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Common::swap32(m_header.unknown_important_1) + header_size;
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}
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u64 TGCFileReader::GetDataSize() const
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{
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return m_size + Common::swap32(m_header.unknown_important_2) -
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Common::swap32(m_header.unknown_important_1);
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}
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bool TGCFileReader::Read(u64 offset, u64 nbytes, u8* out_ptr)
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{
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Interval<u64> first_part;
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Interval<u64> empty_part;
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Interval<u64> last_part;
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u32 header_size = Common::swap32(m_header.header_size);
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SplitInterval(m_file_offset, Interval<u64>{offset, nbytes}, &first_part, &last_part);
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SplitInterval(m_size - header_size, first_part, &first_part, &empty_part);
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// Offsets before m_file_offset are read as usual
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if (!first_part.IsEmpty())
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{
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if (!InternalRead(first_part.start, first_part.length, out_ptr + (first_part.start - offset)))
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return false;
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}
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// If any offset before m_file_offset isn't actually in the file,
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// treat it as 0x00 bytes (so e.g. MD5 calculation of the whole disc won't fail)
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if (!empty_part.IsEmpty())
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std::fill_n(out_ptr + (empty_part.start - offset), empty_part.length, 0);
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// Offsets after m_file_offset are read as if they are (offset - m_file_offset)
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if (!last_part.IsEmpty())
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{
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if (!InternalRead(last_part.start - m_file_offset, last_part.length,
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out_ptr + (last_part.start - offset)))
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return false;
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}
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return true;
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}
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bool TGCFileReader::InternalRead(u64 offset, u64 nbytes, u8* out_ptr)
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{
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u32 header_size = Common::swap32(m_header.header_size);
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if (m_file.Seek(offset + header_size, SEEK_SET) && m_file.ReadBytes(out_ptr, nbytes))
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{
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Replace32(offset, nbytes, out_ptr, 0x420, SubtractBE32(m_header.dol_offset, header_size));
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Replace32(offset, nbytes, out_ptr, 0x424, SubtractBE32(m_header.fst_offset, header_size));
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return true;
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}
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m_file.Clear();
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return false;
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}
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} // namespace DiscIO
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