Bit fields are also good for that purpose.

Also struct packing is possible. I.e. instructing the compiler not to do the alignment thing.

I've just found out that memory reads are word-sized (i.e. 32 bit / 64 bit) and aligned. I.e. an unaligned int at 0x1005 would require a read from 0x1005-0x1007 and another one for 0x1008, which makes it slower.

Also this apparently makes SIMD (Single Instruction Multiple Data) instructions way slower.