Compile-Time SpookyHash

This is a version of Bob Jenkins' SpookyHash hashing algorithm that can be evaluated at compile time. The Hash128, Hash64, and Hash32 functions are now all constexpr and can be used for things like switch case statements. This is still a C++ implementation.

CTSpookyHash's output is identical to the original SpookyHash's, and performance is comparable when used in run-time situations. Just like the original SpookyHash, this code is in the public domain and can be used unconditionally.

How to Use

1. Download CTSpookyHash.h and CTSpookyHash.cpp.
2. Add them to your project.
3. Use CTSpookyHash::Hash128, CTSpookyHash::Hash64 or CTSpookyHash::Hash32 in your code.
4. Profit.

Notes

• This is an implementation of SpookyHash V2.
• C++11 is needed for constexpr.
• Just like the original SpookyHash, this code is not portable to big-endian processors.
• SpookyHash is not cryptographic: do not use it in security scenarios.
• Turning off ALLOW_UNALIGNED_READS will make all functions run-time only.
• Only messages that are smaller than 192 bytes (sc_bufSize) can be evaluated at compile time. Larger messages must be hashed at run-time.
• The functions CTSpookyHash::Init, CTSpookyHash::Update and CTSpookyHash::Final are still run-time only.

Bob Jenkins' original version of SpookyHash is available at http://burtleburtle.net/bob/hash/spooky.html.