From 465175cdf58fecf9098c702feaf8d000f0952973 Mon Sep 17 00:00:00 2001 From: Lioncash Date: Tue, 9 Oct 2018 13:47:59 -0400 Subject: [PATCH] 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. --- src/core/file_sys/ips_layer.cpp | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/src/core/file_sys/ips_layer.cpp b/src/core/file_sys/ips_layer.cpp index 90f91f2305..6c072d0a39 100644 --- a/src/core/file_sys/ips_layer.cpp +++ b/src/core/file_sys/ips_layer.cpp @@ -2,6 +2,7 @@ // Licensed under GPLv2 or any later version // Refer to the license.txt file included. +#include #include #include #include @@ -37,15 +38,33 @@ constexpr std::array, 11> ESCAPE_CHARACTER_M }}; static IPSFileType IdentifyMagic(const std::vector& magic) { - if (magic.size() != 5) + if (magic.size() != 5) { return IPSFileType::Error; - if (magic == std::vector{'P', 'A', 'T', 'C', 'H'}) + } + + constexpr std::array patch_magic{{'P', 'A', 'T', 'C', 'H'}}; + if (std::equal(magic.begin(), magic.end(), patch_magic.begin())) { return IPSFileType::IPS; - if (magic == std::vector{'I', 'P', 'S', '3', '2'}) + } + + constexpr std::array ips32_magic{{'I', 'P', 'S', '3', '2'}}; + if (std::equal(magic.begin(), magic.end(), ips32_magic.begin())) { return IPSFileType::IPS32; + } + return IPSFileType::Error; } +static bool IsEOF(IPSFileType type, const std::vector& data) { + constexpr std::array eof{{'E', 'O', 'F'}}; + if (type == IPSFileType::IPS && std::equal(data.begin(), data.end(), eof.begin())) { + return true; + } + + constexpr std::array 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) { if (in == nullptr || ips == nullptr) return nullptr; @@ -60,8 +79,7 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) { u64 offset = 5; // After header while (ips->Read(temp.data(), temp.size(), offset) == temp.size()) { offset += temp.size(); - if (type == IPSFileType::IPS32 && temp == std::vector{'E', 'E', 'O', 'F'} || - type == IPSFileType::IPS && temp == std::vector{'E', 'O', 'F'}) { + if (IsEOF(type, temp)) { break; } @@ -101,8 +119,9 @@ VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) { } } - if (temp != std::vector{'E', 'E', 'O', 'F'} && temp != std::vector{'E', 'O', 'F'}) + if (!IsEOF(type, temp)) { return nullptr; + } return std::make_shared(std::move(in_data), in->GetName(), in->GetContainingDirectory());