Bit manipulation

Bit manipulation is the act of algorithmically manipulating bits or other pieces of data shorter than a word. Computer programming tasks that require bit manipulation include low-level device control, error detection and correction algorithms, data compression, encryption algorithms, and optimization. For most other tasks, modern programming languages allow the programmer to work directly with abstractions instead of bits that represent those abstractions.

Source code that does bit manipulation makes use of the bitwise operations: AND, OR, XOR, NOT, and possibly other operations analogous to the Boolean operators; there are also bit shifts and operations to count ones and zeros, find high and low one or zero, set, reset and test bits, extract and insert fields, mask and zero fields, gather and scatter bits to and from specified bit positions or fields.

Integer arithmetic operators can also effect bit-operations in conjunction with the other operators.

Bit manipulation, in some cases, can obviate or reduce the need to loop over a data structure and can give manyfold speed-ups, as bit manipulations are processed in parallel. However if the operation is unusual or costly to implement its inclusion cannot be justified, inspiring innovative research.

Terminology

Bit twiddling, bit fiddling, bit bashing, and bit gymnastics are often used interchangeably with bit manipulation, but sometimes exclusively refer to clever or non-obvious ways or uses of bit manipulation, or tedious or challenging low-level device control data manipulation tasks, for which the more accurate colloquial term is known as bit banging.

The term bit twiddling dates from early computing hardware, where computer operators would make adjustments by tweaking or twiddling computer controls. As computer programming languages evolved, programmers adopted the term to mean any handling of data that involved bit-level computation.