From 5124b540279bc08d14da049a6d4180265f4a799a Mon Sep 17 00:00:00 2001
From: Wunkolo <Wunkolo@gmail.com>
Date: Sat, 10 Jun 2023 01:42:35 -0700
Subject: [PATCH] Add `FourCC`/`_u32` helper function/literals

Portable code for turning string-based four-character-codes like
`"BLAH"_u32` into a 32-bit integer at compile-time.
---
 include/helpers.hpp      | 22 ++++++++++++++++++++++
 src/core/loader/ncch.cpp |  2 +-
 src/core/loader/ncsd.cpp |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/include/helpers.hpp b/include/helpers.hpp
index ee1a1dac..25c2ef2d 100644
--- a/include/helpers.hpp
+++ b/include/helpers.hpp
@@ -141,6 +141,28 @@ constexpr size_t operator""_GB(unsigned long long int x) {
     return 1024_MB * x;
 }
 
+// Utility user-literal/metaprogramming-type for turning four-character-codes
+// into 32-bit integers at compile-time
+// Ex: "BLAH"_u32, "HEAD"_u32, "END "_u32
+template <std::size_t N>
+struct FourCC {
+	u32 value;
+
+	constexpr FourCC(const char (&identifier)[N]) : value(0) {
+		static_assert(N == 5, "FourCC must be 4 characters");
+		if constexpr (std::endian::native == std::endian::big) {
+			value = ((identifier[3] << 0) | (identifier[2] << 8) | (identifier[1] << 16) | (identifier[0] << 24));
+		} else {
+			value = ((identifier[3] << 24) | (identifier[2] << 16) | (identifier[1] << 8) | (identifier[0] << 0));
+		}
+	}
+};
+
+template <FourCC code>
+constexpr std::uint32_t operator""_u32() {
+        return code.value;
+}
+
 // useful macros
 // likely/unlikely
 #ifdef __GNUC__
diff --git a/src/core/loader/ncch.cpp b/src/core/loader/ncch.cpp
index c3dd8d2e..6eb4506c 100644
--- a/src/core/loader/ncch.cpp
+++ b/src/core/loader/ncch.cpp
@@ -5,7 +5,7 @@
 #include "memory.hpp"
 
 bool NCCH::loadFromHeader(u8* header, IOFile& file) {
-    if (header[0x100] != 'N' || header[0x101] != 'C' || header[0x102] != 'C' || header[0x103] != 'H') {
+    if (*(u32*)&header[0x100] != "NCCH"_u32) {
         printf("Invalid header on NCCH\n");
         return false;
     }
diff --git a/src/core/loader/ncsd.cpp b/src/core/loader/ncsd.cpp
index bf93f490..cc311eba 100644
--- a/src/core/loader/ncsd.cpp
+++ b/src/core/loader/ncsd.cpp
@@ -17,7 +17,7 @@ std::optional<NCSD> Memory::loadNCSD(const std::filesystem::path& path) {
         return std::nullopt;
     }
 
-    if (magic[0] != 'N' || magic[1] != 'C' || magic[2] != 'S' || magic[3] != 'D') {
+    if (*(u32*)&magic[0] != "NCSD"_u32) {
         printf("NCSD with wrong magic value\n");
         return std::nullopt;
     }