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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.
This commit is contained in:
Lioncash 2018-10-09 13:47:59 -04:00
parent 9ff743bc0a
commit 465175cdf5
1 changed files with 25 additions and 6 deletions
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31
src/core/file_sys/ips_layer.cpp
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@ -2,6 +2,7 @@
// Licensed under GPLv2 or any later version // Licensed under GPLv2 or any later version
// Refer to the license.txt file included. // Refer to the license.txt file included.
#include <algorithm>
#include <cstring> #include <cstring>
#include <map> #include <map>
#include <sstream> #include <sstream>
@ -37,15 +38,33 @@ constexpr std::array<std::pair<const char*, const char*>, 11> ESCAPE_CHARACTER_M
}}; }};
static IPSFileType IdentifyMagic(const std::vector<u8>& magic) { static IPSFileType IdentifyMagic(const std::vector<u8>& magic) {
if (magic.size() != 5) if (magic.size() != 5) {
return IPSFileType::Error; return IPSFileType::Error;
if (magic == std::vector<u8>{'P', 'A', 'T', 'C', 'H'}) }
constexpr std::array<u8, 5> patch_magic{{'P', 'A', 'T', 'C', 'H'}};
if (std::equal(magic.begin(), magic.end(), patch_magic.begin())) {
return IPSFileType::IPS; return IPSFileType::IPS;
if (magic == std::vector<u8>{'I', 'P', 'S', '3', '2'}) }
constexpr std::array<u8, 5> ips32_magic{{'I', 'P', 'S', '3', '2'}};
if (std::equal(magic.begin(), magic.end(), ips32_magic.begin())) {
return IPSFileType::IPS32; return IPSFileType::IPS32;
}
return IPSFileType::Error; return IPSFileType::Error;
} }
static bool IsEOF(IPSFileType type, const std::vector<u8>& data) {
constexpr std::array<u8, 3> eof{{'E', 'O', 'F'}};
if (type == IPSFileType::IPS && std::equal(data.begin(), data.end(), eof.begin())) {
return true;
}
constexpr std::array<u8, 4> eeof{{'E', 'E', 'O', 'F'}};
return type == IPSFileType::IPS32 && std::equal(data.begin(), data.end(), eeof.begin());
}
VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) { VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
if (in == nullptr || ips == nullptr) if (in == nullptr || ips == nullptr)
return nullptr; return nullptr;
@ -60,8 +79,7 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
u64 offset = 5; // After header u64 offset = 5; // After header
while (ips->Read(temp.data(), temp.size(), offset) == temp.size()) { while (ips->Read(temp.data(), temp.size(), offset) == temp.size()) {
offset += temp.size(); offset += temp.size();
if (type == IPSFileType::IPS32 && temp == std::vector<u8>{'E', 'E', 'O', 'F'} || if (IsEOF(type, temp)) {
type == IPSFileType::IPS && temp == std::vector<u8>{'E', 'O', 'F'}) {
break; break;
} }
@ -101,8 +119,9 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
} }
} }
if (temp != std::vector<u8>{'E', 'E', 'O', 'F'} && temp != std::vector<u8>{'E', 'O', 'F'}) if (!IsEOF(type, temp)) {
return nullptr; return nullptr;
}
return std::make_shared<VectorVfsFile>(std::move(in_data), in->GetName(), return std::make_shared<VectorVfsFile>(std::move(in_data), in->GetName(),
in->GetContainingDirectory()); in->GetContainingDirectory());