Add HashTool

This is probably my last addition to the C++ version of this code,
at least if an Experimental ~~Rodeo~~ Rewrite doesn't end up panning
out.

This is a tool for generating the HashID values that the game uses.

Maybe later on I might try and see if I can write a multi-threaded
hash cracker, or better yet, a GPU powered one (no better way to
try and learn GPGPU then actually doing it!), but for now, this is
all you get.

Feel free to lavish in my argument parsing implementation. I just wanted
something simple and fairly easy to read, and this seems to work ok,
while still being platform-independent (no getopt, and I wouldn't need to
drag in additional code to reimplement getopt or such for Windows/Mac/...)

src/tools/CMakeLists.txt

@@ -15,3 +15,11 @@ set_target_properties(jmmt_pack_extractor PROPERTIES
 		CXX_STANDARD 20
 		CXX_STANDARD_REQUIRED ON
 		)
+
+add_executable(jmmt_hashtool jmmt_hashtool.cpp)
+target_link_libraries(jmmt_hashtool PUBLIC jmmt)
+
+set_target_properties(jmmt_hashtool PROPERTIES
+		CXX_STANDARD 20
+		CXX_STANDARD_REQUIRED ON
+		)

src/tools/jmmt_hashtool.cpp

@@ -0,0 +1,125 @@
+// JMMT HashTool
+
+#include <jmmt/crc.h>
+
+#include <array>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <string_view>
+
+struct Arguments {
+	enum class OutputMode {
+		Hex,	///< Hexadecimal output.
+		Decimal ///< Decimal output.
+	};
+
+	char* hashName {};
+	bool useCase { false };
+	OutputMode outMode { OutputMode::Hex };
+
+	/** Parse arguments from the main() argv. **/
+	static Arguments FromArgv(int argc, char** argv) {
+		Arguments args;
+		args.progname = argv[0];
+
+		// no options provided
+		if(argc == 1) {
+			args.DispHelp();
+			std::exit(1);
+		}
+
+		// non-pepper getopt(). I'm too lazy to make it any better though
+		for(int i = 1; i < argc; ++i) {
+			if(argv[i][0] == '-' && argv[i][1] != '\0') {
+				char sw = argv[i][1];
+
+				switch(sw) {
+						// flag options
+
+					case 'c':
+						args.useCase = true;
+						break;
+
+					case 'd':
+						if(args.outMode == OutputMode::Hex)
+							args.outMode = OutputMode::Decimal;
+						break;
+
+					case 'h':
+						if(args.outMode == OutputMode::Decimal)
+							args.outMode = OutputMode::Hex;
+						break;
+
+					// terminals
+					case '?':
+						args.DispHelp();
+						std::exit(0);
+
+					default:
+						std::printf("Unknown command-line switch '-%c'\n", sw);
+						args.DispHelp();
+						std::exit(1);
+				}
+			} else {
+				// Assume any non-positional argument is what we're supposed to hash
+				args.hashName = argv[i];
+			}
+		}
+		return args;
+	}
+
+	bool Validate() const {
+		if(!hashName) {
+			std::printf("No hash name provided\n");
+			DispHelp();
+			return false;
+		}
+		return true;
+	}
+
+   private:
+	char* progname {};
+
+	void DispHelp() const {
+		// no I'm not sorry
+		std::printf(
+		// clang-format off
+			"JMMT HashTool - a thing for generating TECH HashID's\n"
+			"Usage: %s [-c] [-?] <hash object>\n"
+			"    -c Use case-senstive HashID variant (default is case-insensitive)\n"
+			"    -d Output in decimal (default hex)\n"
+			"    -h Output as hexadecimal (if previously overridden; kinda pointless)\n"
+			"    -? Show this help message (and exit)\n",
+			progname
+		// clang-format on
+		);
+	}
+};
+
+int main(int argc, char** argv) {
+	auto args = Arguments::FromArgv(argc, argv);
+
+	if(!args.Validate()) {
+		return 1;
+	}
+
+	jmmt::crc32_t result {};
+	if(args.useCase)
+		result = jmmt::HashStringCase(args.hashName);
+	else
+		result = jmmt::HashString(args.hashName);
+
+	// clang-format off
+	using enum Arguments::OutputMode;
+	switch(args.outMode) {
+		case Decimal: std::printf("%d\n", result);  break;	
+		case Hex: std::printf("0x%08x\n", result);  break;
+#ifdef __GNUC__
+		// Mark this path explicitly as UB
+		default: __builtin_unreachable();
+#endif
+	}
+	// clang-format on
+	return 0;
+}