Nonbytealigned

Nonbytealigned refers to data whose boundaries do not coincide with standard 8-bit bytes. In nonbytealigned data, a field may begin at an offset within a byte and have a length that is not a multiple of 8 bits. This contrasts with byte-aligned data, where most structures start at byte boundaries and fields are multiples of 8 bits long.

Nonbytealignment is common in bit-oriented data formats and communications where packing fields tightly saves bandwidth or space. Examples include certain serial or radio protocols that define field lengths in exact bits, as well as bitstreams used in compressed video and audio, where values are emitted as a continuous sequence of bits rather than neatly packaged bytes. Some file formats and standards also include bit strings or other constructs that require bit-level management.

Handling nonbytealigned data requires bit-level operations, such as shifting and masking, and careful tracking of bit offsets. When data crosses byte boundaries, endianness can influence how bits are assembled into bytes. In programming languages, support for nonbytealigned fields varies. C and C++ offer bit-field constructs, but their layout is implementation-dependent and may not be portable across compilers. Some microcontrollers provide bit-addressable memory to access individual bits directly, illustrating hardware-level nonbytealignment.

Related concepts include bit fields, bit packing, and bitstreams. Nonbytealigned data often demands specialized parsers or decoders capable of bit-level reading and accurate handling of partial-byte boundaries to ensure correct interpretation.