ips_layer: Avoid constructing std::vector instances where not necessary
We can just compare the existing std::vector instance with a constexpr std::array containing the desired match. This is lighter resource-wise, as we don't need to allocate on the heap.
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@ -2,6 +2,7 @@
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <algorithm>
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#include <cstring>
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#include <map>
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#include <sstream>
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@ -37,15 +38,33 @@ constexpr std::array<std::pair<const char*, const char*>, 11> ESCAPE_CHARACTER_M
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}};
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static IPSFileType IdentifyMagic(const std::vector<u8>& magic) {
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if (magic.size() != 5)
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if (magic.size() != 5) {
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return IPSFileType::Error;
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if (magic == std::vector<u8>{'P', 'A', 'T', 'C', 'H'})
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}
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constexpr std::array<u8, 5> patch_magic{{'P', 'A', 'T', 'C', 'H'}};
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if (std::equal(magic.begin(), magic.end(), patch_magic.begin())) {
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return IPSFileType::IPS;
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if (magic == std::vector<u8>{'I', 'P', 'S', '3', '2'})
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}
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constexpr std::array<u8, 5> ips32_magic{{'I', 'P', 'S', '3', '2'}};
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if (std::equal(magic.begin(), magic.end(), ips32_magic.begin())) {
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return IPSFileType::IPS32;
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}
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return IPSFileType::Error;
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}
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static bool IsEOF(IPSFileType type, const std::vector<u8>& data) {
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constexpr std::array<u8, 3> eof{{'E', 'O', 'F'}};
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if (type == IPSFileType::IPS && std::equal(data.begin(), data.end(), eof.begin())) {
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return true;
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}
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constexpr std::array<u8, 4> eeof{{'E', 'E', 'O', 'F'}};
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return type == IPSFileType::IPS32 && std::equal(data.begin(), data.end(), eeof.begin());
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}
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VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
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if (in == nullptr || ips == nullptr)
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return nullptr;
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@ -60,8 +79,7 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
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u64 offset = 5; // After header
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while (ips->Read(temp.data(), temp.size(), offset) == temp.size()) {
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offset += temp.size();
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if (type == IPSFileType::IPS32 && temp == std::vector<u8>{'E', 'E', 'O', 'F'} ||
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type == IPSFileType::IPS && temp == std::vector<u8>{'E', 'O', 'F'}) {
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if (IsEOF(type, temp)) {
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break;
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}
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@ -101,8 +119,9 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
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}
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}
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if (temp != std::vector<u8>{'E', 'E', 'O', 'F'} && temp != std::vector<u8>{'E', 'O', 'F'})
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if (!IsEOF(type, temp)) {
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return nullptr;
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}
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return std::make_shared<VectorVfsFile>(std::move(in_data), in->GetName(),
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in->GetContainingDirectory());
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