bit bashing
(Also "bit diddling" or bit twiddling). Any of several kinds of low-level programming characterised by manipulation of bit, flag, nibble, and other smaller-than-character-sized pieces of data. These include low-level device control, encryption algorithms, checksum and error-correcting codes, hash functions, some flavours of graphics programming (see bitblt), and assembler/compiler code generation. May connote either tedium or a real technical challenge (more usually the former). "The command decoding for the new tape driver looks pretty solid but the bit-bashing for the control registers still has bugs." See also bit bang, mode bit.