Converting Bit Field to int

Question

I have bit field declared this way:

typedef struct morder {
    unsigned int targetRegister : 3;
    unsigned int targetMethodOfAddressing : 3;
    unsigned int originRegister : 3;
    unsigned int originMethodOfAddressing : 3;
    unsigned int oCode : 4;
} bitset;

I also have int array, and I want to get int value from this array, that represents the actual value of this bit field (which is actually some kind of machine word that I have the parts of it, and I want the int representation of the whole word).

Answer 1

You can use a union:

typedef union bitsetConvertor {
    bitset bs;
    uint16_t i;
} bitsetConvertor;

bitsetConvertor convertor;
convertor.i = myInt;
bitset bs = convertor.bs;

Or you can use a cast:

bitset bs = *(bitset *)&myInt;

Or you can use an anonymous struct within a union:

typedef union morder {
    struct {
        unsigned int targetRegister : 3;
        unsigned int targetMethodOfAddressing : 3;
        unsigned int originRegister : 3;
        unsigned int originMethodOfAddressing : 3;
        unsigned int oCode : 4;
    };

    uint16_t intRepresentation;
} bitset;

bitset bs;
bs.intRepresentation = myInt;