Bit Twiddling Hacks

• Merge bits from two values according to a mask
• Conditionally set or clear bits without branching
• Conditionally negate a value without branching
• Detect if two integers have opposite signs
• Compute the integer absolute value (abs) without branching
• Compute the minimum (min) or maximum (max) of two integers without branching
• Determining if an integer is a power of 2

The Aggregate Magic Algorithms

see also

• Mel’s Hack – The Missing Bits - a finite loop with no exit condition.
• Unconditionally Readable C++ - some advice how to write readable condition in c++