bitmasking

Bitmasking is a technique in computer science that uses bitwise operations to manipulate individual bits within an integer. A bit mask is a value whose binary representation indicates which bits should be affected when combined with another value. Bitmasks enable compact and fast control of multiple boolean flags or fields.

Common bitwise operations with masks include AND, OR, XOR, and NOT. Setting a bit is done with OR: x = x | mask. Clearing a bit uses AND with the complement of the mask: x = x & ~mask. Toggling a bit uses XOR: x = x ^ mask. Testing whether a bit is set typically uses AND: (x & mask) != 0. Shifts (left or right) are often used to position a mask at the desired bit index.

Masks are created by setting specific bit positions. A single-bit mask is obtained with 1 << k, which has a 1 in position k. For multiple bits, masks can be combined with OR, for example (1 << a) | (1 << b). Masks can also be negated with NOT to clear or invert certain bits, depending on the operation.

Applications of bitmasking include managing flags and feature toggles, representing permissions, manipulating status registers in low-level code, and packing multiple boolean or small-range values into a single integer. It is commonly used in systems programming, embedded development, and performance-critical software across languages such as C, C++, Java, and Python.

Example: let x = 0b1010; let mask = 1 << 1; if (x & mask) then bit 1 is set. Setting, clearing, and toggling follow the standard patterns described above.