What is Bit Masking?

Bit masking is a technique used in computer programming to manipulate specific bits within a binary number. It involves applying a mask to a value to keep, change, or clear certain bits. This is achieved using bitwise operations such as AND, OR, XOR, and NOT.

Key Concepts of Bit Masking

1. Mask Definition: A mask is a binary number that specifies which bits in another binary number should be kept, changed, or cleared. For example, a mask of 00001111 would focus on the lower four bits of a byte.

2. Bitwise Operations:

   • AND (&): Used to clear bits. Only the bits that are 1 in both the mask and the value remain 1.
   • OR (|): Used to set bits. Any bit that is 1 in the mask will be set to 1 in the value.
   • XOR (^): Used to toggle bits. Bits that are 1 in the mask will be flipped in the value.
   • NOT (~): Used to invert bits. All 0s become 1s and all 1s become 0s.

Examples of Bit Masking Operations

1. Setting a Bit:
   To set a specific bit to 1, use the OR operation with a mask that has a 1 at the bit position you want to set.

   value |= (1 << bit_position);

   Example: To set the 3rd bit of 01000010:

   01000010
   OR
   00001000
   ------
   01001010

2. Clearing a Bit:
   To clear a specific bit to 0, use the AND operation with a mask that has a 0 at the bit position you want to clear.

   value &= ~(1 << bit_position);

   Example: To clear the 3rd bit of 01001010:

   01001010
   AND
   11110111
   ------
   01000010

3. Toggling a Bit:
   To toggle a specific bit, use the XOR operation with a mask that has a 1 at the bit position you want to toggle.

   value ^= (1 << bit_position);

   Example: To toggle the 3rd bit of 01000010:

   01000010
   XOR
   00001000
   ------
   01001010

4. Checking a Bit:
   To check if a specific bit is set, use the AND operation with a mask that has a 1 at the bit position you want to check.

   bit = value & (1 << bit_position);

   Example: To check the 3rd bit of 01001010:

   01001010
   AND
   00001000
   ------
   00001000

Applications of Bit Masking

• Optimization: Bit masking can replace more expensive operations with faster bit-level operations.
• Memory Efficiency: It allows compact storage of data, such as using a single integer to repres...