Clear Bit (Bit Clear)
Reset a specific bit in a binary number to zero
Bit Clear Calculator
Bit Operation: Clear
This function clears (sets to 0) a specific bit in a binary number. The numbering starts with the rightmost bit at position 0.
Bit-Clear Visualization
Example: FF (hex) → Clear Bit 2
Bit Clear Operation
Target Bit = 0
Other bits remain unchanged
Logical AND operation with maskImportant Properties
- Bit position starts at 0 (right)
- Only the specified bit is set to 0
- Already set 0-bits remain unchanged
- Operation is idempotent (multiple executions = same effect)
Mathematical Foundations of Bit-Clear Operation
The Bit-Clear operation uses a logical AND operation with a special mask:
Mask Creation
n = bit position, ~ = bitwise negation, << = left shift
Bit-Clear Operation
Logical AND operation with the generated mask
Bit-Clear Formulas and Examples
General Bit-Clear Formula
Where x is the original number and n is the bit position
Step-by-Step Example: Clear Bit 2 in FF (hex)
1. Original: 11111111₂ (FF hex = 255 dec)
2. Bit Position: n = 2
3. Create Mask: 1 << 2 = 00000100₂
4. Negate Mask: ~00000100₂ = 11111011₂
5. AND Operation: 11111111₂ & 11111011₂ = 11111011₂
6. Result: FB hex = 251 dec
More Examples
Original: 1111₂ (15)
Mask: ~0001₂ = 1110₂
Result: 1111₂ & 1110₂ = 1110₂ (14)
Original: 11111111₂ (255)
Mask: ~00001000₂ = 11110111₂
Result: 11110111₂ (247)
Bit Position Mapping
Position 0 = least significant bit (LSB), Position 7 = most significant bit (MSB)
Bit-Clear Reference
Standard Example
Bit Values (Powers of 2)
Bit 0: 2⁰ = 1
Bit 1: 2¹ = 2
Bit 2: 2² = 4
Bit 3: 2³ = 8
Bit 4: 2⁴ = 16
Bit 5: 2⁵ = 32
Bit 6: 2⁶ = 64
Bit 7: 2⁷ = 128
Logical Operators
&: bitwise AND
~: bitwise negation (NOT)
<<: left shift
>>: right shift
Common Operations
Set Bit: x | (1 << n)
Clear Bit: x & ~(1 << n)
Toggle Bit: x ^ (1 << n)
Check Bit: (x >> n) & 1
Bit Manipulation - Detailed Description
Bit Clear Operation
The bit-clear operation is a fundamental bitwise operation that sets a specific bit in a binary number to 0, while leaving all other bits unchanged. This operation is particularly important in systems programming and embedded systems.
• Target bit is always set to 0
• Other bits remain unchanged
• Operation is idempotent
• Based on logical AND operation
Mask Technique
The mask technique is the heart of the bit-clear operation. A mask is created that contains a 0 at the desired position and 1s at all other positions. This mask is then AND-combined with the original number.
Mask Creation
1. Create bit pattern: 1 << n
2. Negate the pattern: ~(1 << n)
3. AND operation: original & mask
Practical Applications
Bit-clear operations are used in many areas, from hardware control to data processing. They enable precise control over individual bits without affecting other data areas.
• Hardware register control
• Status flag management
• Bit masks for permissions
• Data filtering and cleaning
Bit Position System
The bit position system starts at 0 for the least significant bit (LSB) and increases to the left. Position n corresponds to the decimal value 2^n.
Important Notes
- Bit numbering starts at 0 (not 1)
- Position 0 = rightmost bit (least significant)
- Already set 0-bits remain unchanged
- Operation works with all number systems
Practical Bit-Clear Examples
Hardware Register
Scenario: Turn off LED
Register: 10110111₂
Clear Bit 3: 10100111₂
Effect: LED at position 3 off
Status Flags
Scenario: Clear error flag
Status: 11111111₂
Clear Bit 7: 01111111₂
Effect: Error flag cleared
Permissions
Scenario: Revoke write permission
Rights: 111₂ (rwx)
Clear Bit 1: 101₂ (r-x)
Effect: Read and execute only
Programming Tips
- Use constants: #define BIT2 (1<<2)
- Define macros: #define CLEAR_BIT(x,n) ((x) & ~(1<<(n)))
- Use bit fields: for structured data
- Debugging: Binary output for control
- Portability: Consider bit size (8/16/32/64 bit)
- Performance: Bit operations are very fast
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