godot/core/bitfield_dynamic.h

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/*  bitfield_dynamic.h                                                   */
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#ifndef BITFIELD_DYNAMIC_H
#define BITFIELD_DYNAMIC_H

#include "core/error_macros.h"

class BitFieldDynamic {
public:
	~BitFieldDynamic() { destroy(); }

private:
	// prevent copying (see effective C++ scott meyers)
	// there is no implementation for copy constructor, hence compiler will complain if you try to copy
	// feel free to add one if needed...
	BitFieldDynamic &operator=(const BitFieldDynamic &);

public:
	// create automatically blanks
	void create(uint32_t p_num_bits, bool p_blank = true);
	void destroy();

	// public funcs
	uint32_t get_num_bits() const { return _num_bits; }
	uint32_t get_bit(uint32_t p_bit) const;
	void set_bit(uint32_t p_bit, uint32_t p_set);
	bool check_and_set(uint32_t p_bit);
	void blank(bool p_set_or_zero = false);
	void invert();
	void copy_from(const BitFieldDynamic &p_source);

	// loading / saving
	uint8_t *get_data() { return _data; }
	const uint8_t *get_data() const { return _data; }
	uint32_t get_num_bytes() const { return _num_bytes; }

protected:
	// member vars
	uint8_t *_data = nullptr;
	uint32_t _num_bytes = 0;
	uint32_t _num_bits = 0;
};

inline uint32_t BitFieldDynamic::get_bit(uint32_t p_bit) const {
	DEV_ASSERT(_data);
	uint32_t byte_number = p_bit >> 3; // divide by 8
	DEV_ASSERT(byte_number < _num_bytes);
	uint8_t uc = _data[byte_number];
	uint32_t bit_set = uc & (1 << (p_bit & 7));
	return bit_set;
}

inline bool BitFieldDynamic::check_and_set(uint32_t p_bit) {
	DEV_ASSERT(_data);
	uint32_t byte_number = p_bit >> 3; // divide by 8
	DEV_ASSERT(byte_number < _num_bytes);
	uint8_t &uc = _data[byte_number];
	uint32_t mask = (1 << (p_bit & 7));
	uint32_t bit_set = uc & mask;
	if (bit_set) {
		return false;
	}

	// set
	uc = uc | mask;
	return true;
}

inline void BitFieldDynamic::set_bit(uint32_t p_bit, uint32_t p_set) {
	DEV_ASSERT(_data);
	uint32_t byte_number = p_bit >> 3; // divide by 8
	DEV_ASSERT(byte_number < _num_bytes);
	uint8_t uc = _data[byte_number];
	uint32_t mask = 1 << (p_bit & 7);
	if (p_set) {
		uc = uc | mask;
	} else {
		uc &= ~mask;
	}
	_data[byte_number] = uc;
}

#endif