https://www.youtube.com/watch?v=TYqbgvHfxjM&list=PLV_I43TsVVM6LgrbYTFO9SXJLT8pPN2DM&index=1&t=1s&ab_channel=MeetingCpp

register.cpp

#include <cstdint>

// normal device class e.g., i2c, spi
class Device {
public:
	Device() {}
	bool write8(uint8_t page, uint8_t addr, uint8_t v)
	{
        return true;
    }
	
	bool write16(uint8_t page, uint8_t addr, uint16_t v)
	{
        return true;
    }
};

// common register structure
struct Registers {
	// one specific register called control
    union Control {
		// how to locate the register
        enum { PAGE = 0x16, ADDRESS = 0x17 };
		// value options for one section of this register
        struct OPM {
            enum { NO_CHANGE = 0, AS_STANDBY = 1 };
        };
		// bitfield
        struct Bits {
            uint16_t OPM : 2;
            uint16_t CTRL_BR1 : 2;
            uint16_t CTRL_BR2 : 2;
        } bits;
		// raw value
        uint16_t raw;
		
		// union constructor
        Control(uint16_t v = 0x00) : raw(v) {}
    };
};

int main() {

    Registers::Control r;
    r.bits.OPM = Registers::Control::OPM::AS_STANDBY;

    Device device;
    device.write16(Registers::Control::PAGE, Registers::Control::ADDRESS,
                   r.raw);

    return 0;
}