re3ake

#pragma once
#include <string>
#include <array>
#include <cstdarg>

#define BEGIN_NAMESPACE( x ) namespace x {
#define END_NAMESPACE }

BEGIN_NAMESPACE(XorCompileTime)

constexpr auto time = __TIME__;
constexpr auto seed = static_cast< int >(time[7]) + static_cast< int >(time[6]) * 10 + static_cast< int >(time[4]) * 60 + static_cast< int >(time[3]) * 600 + static_cast< int >(time[1]) * 3600 + static_cast< int >(time[0]) * 36000;

// 1988, Stephen Park and Keith Miller
// "Random Number Generators: Good Ones Are Hard To Find", considered as "minimal standard"
// Park-Miller 31 bit pseudo-random number generator, implemented with G. Carta's optimisation:
// with 32-bit math and without division

template < int N >
struct RandomGenerator {
private:
	static constexpr unsigned a = 16807; // 7^5
	static constexpr unsigned m = 2147483647; // 2^31 - 1

	static constexpr unsigned s = RandomGenerator< N - 1 >::value;
	static constexpr unsigned lo = a * (s & 0xFFFF); // Multiply lower 16 bits by 16807
	static constexpr unsigned hi = a * (s >> 16); // Multiply higher 16 bits by 16807
	static constexpr unsigned lo2 = lo + ((hi & 0x7FFF) << 16); // Combine lower 15 bits of hi with lo's upper bits
	static constexpr unsigned hi2 = hi >> 15; // Discard lower 15 bits of hi
	static constexpr unsigned lo3 = lo2 + hi;

public:
	static constexpr unsigned max = m;
	static constexpr unsigned value = lo3 > m ? lo3 - m : lo3;
};

template <>
struct RandomGenerator< 0 > {
	static constexpr unsigned value = seed;
};

template < int N, int M >
struct RandomInt {
	static constexpr auto value = RandomGenerator< N + 1 >::value % M;
};

template < int N >
struct RandomChar {
	static const char value = static_cast< char >(1 + RandomInt< N, 0x7F - 1 >::value);
};

template < size_t N, int K >
struct XorString {
private:
	const char _key;
	std::array< char, N + 1 > _encrypted;

	constexpr char enc(char c) const {
		return c ^ _key;
	}

	char dec(char c) const {
		return c ^ _key;
	}

public:
	template < size_t... Is >
	constexpr __forceinline XorString(const char* str, std::index_sequence< Is... >) : _key(RandomChar< K >::value), _encrypted{ enc(str[Is])... } {
	}

	__forceinline decltype(auto) decrypt(void) {
		for (size_t i = 0; i < N; ++i) {
			_encrypted[i] = dec(_encrypted[i]);
		}
		_encrypted[N] = '\0';
		return _encrypted.data();
	}
};

//--------------------------------------------------------------------------------
//-- Note: XorStr will __NOT__ work directly with functions like printf.
//         To work with them you need a wrapper function that takes a const char*
//         as parameter and passes it to printf and alike.
//
//         The Microsoft Compiler/Linker is not working correctly with variadic 
//         templates!
//  
//         Use the functions below or use std::cout (and similar)!
//--------------------------------------------------------------------------------

static auto w_printf = [](const char* fmt, ...) {
	va_list args;
	va_start(args, fmt);
	vprintf_s(fmt, args);
	va_end(args);
};

static auto w_printf_s = [](const char* fmt, ...) {
	va_list args;
	va_start(args, fmt);
	vprintf_s(fmt, args);
	va_end(args);
};

static auto w_sprintf = [](char* buf, const char* fmt, ...) {
	va_list args;
	va_start(args, fmt);
	vsprintf(buf, fmt, args);
	va_end(args);
};

static auto w_sprintf_s = [](char* buf, size_t buf_size, const char* fmt, ...) {
	va_list args;
	va_start(args, fmt);
	vsprintf_s(buf, buf_size, fmt, args);
	va_end(args);
};

#ifdef NDEBUG
#define XorStr( s ) ( XorCompileTime::XorString< sizeof( s ) - 1, __COUNTER__ >( s, std::make_index_sequence< sizeof( s ) - 1>() ).decrypt() )
#else
#define XorStr( s ) ( s )
#endif

END_NAMESPACE