BL3Lua/BitFields.hpp

#pragma once
#include <cstddef>
#include <cstdint>
#include <climits>
#include <type_traits>

// https://stackoverflow.com/a/263738
/* a=target variable, b=bit number to act upon 0-n */
#define BIT_SET(a,b) ((a) |= (1ULL<<(b)))
#define BIT_CLEAR(a,b) ((a) &= ~(1ULL<<(b)))
#define BIT_FLIP(a,b) ((a) ^= (1ULL<<(b)))
#define BIT_CHECK(a,b) (!!((a) & (1ULL<<(b))))        // '!!' to make sure this returns 0 or 1

/* x=target variable, y=mask */
#define BITMASK_SET(x,y) ((x) |= (y))
#define BITMASK_CLEAR(x,y) ((x) &= (~(y)))
#define BITMASK_FLIP(x,y) ((x) ^= (y))
#define BITMASK_CHECK_ALL(x,y) (!(~(x) & (y)))
#define BITMASK_CHECK_ANY(x,y) ((x) & (y))

namespace itsy_bitsy {

	template <std::size_t sz, typename C = void>
	struct bit_type {
		typedef uint64_t type;
	};

	template <std::size_t sz>
	struct bit_type<sz, std::enable_if_t<(sz <= 1)>> {
		typedef bool type;
	};

	template <std::size_t sz>
	struct bit_type<sz, std::enable_if_t<(sz > 2 && sz <= 16)>> {
		typedef uint16_t type;
	};

	template <std::size_t sz>
	struct bit_type<sz, std::enable_if_t<(sz > 16 && sz <= 32)>> {
		typedef uint32_t type;
	};

	template <std::size_t sz>
	struct bit_type<sz, std::enable_if_t<(sz > 32 && sz <= 64)>> {
		typedef uint64_t type;
	};

	template <std::size_t sz>
	using bit_type_t = typename bit_type<sz>::type;

	template <typename T, typename V>
	bool vcxx_warning_crap(std::true_type, V val) {
		return val != 0;
	}

	template <typename T, typename V>
	T vcxx_warning_crap(std::false_type, V val) {
		return static_cast<T>(val);
	}

	template <typename T, typename V>
	auto vcxx_warning_crap(V val) {
		return vcxx_warning_crap<T>(std::is_same<bool, T>(), val);
	}

	template <typename Base, std::size_t baseOffset = 0x0, std::size_t bit_target = 0x0, std::size_t size = 0x1>
	void write(Base& b, bit_type_t<size> bits) {
		uintptr_t baseAddr = reinterpret_cast<uintptr_t>(&b);
		uintptr_t offs = baseOffset;
		unsigned char* byt = reinterpret_cast<unsigned char*>(baseAddr + offs);
		char testb = *byt & (1 << bit_target);
		if (bits)
			BIT_SET(*byt, bit_target);
		else
			BIT_CLEAR(*byt, bit_target);
	}

	template <typename Base, std::size_t baseOffset = 0x0, std::size_t bit_target = 0x0, std::size_t size = 0x1>
	bit_type_t<size> read(Base& b) {
		uintptr_t baseAddr = reinterpret_cast<uintptr_t>(&b);
		uintptr_t offs = baseOffset;
		unsigned char* byt = reinterpret_cast<unsigned char*>(baseAddr + offs);
		char test = *byt & (1 << bit_target);
		if (test)
			return true;
		return false;
	}
}