Etikettarkiv: programming

Free Programming Books

DSC_5834 RKRM set of books
Amiga Books

Free Programming Books covers most of the today programming languages and many you did never take a look at (or need) from the past.  All books are ebooks free for download and may be an assistance to you if you are learning a new language or just want to brush up your knowledge for some reason.

There are 338 books in this collection so you will have plenty to read for a while now!


Recently I needed a fast an reliable hash function with good statistics on distribution and I came across what is commonly known as the FNV-hash function. FNV is short for Fowler / Noll / Vo the last names of the three most prominent people contributing to the hashing function.

Basically the FNV algorithm is a very simple one but it is effective and yields astonishingly well differentiated hashes. It has been used in many different codes and both the algoritm itself and a standard source coude has been released into the public domain.

Pseudo code

hash = offset_basis
for each octet_of_data to be hashed
	hash = hash * FNV_prime
	hash = hash xor octet_of_data
return has

The above is called the FNV-1 algorithm. If the multiplication and the XOR change place we get a variant called the FNV-1a which is very similar in all aspects of the first one. I decided to implement both and hash both as 32 bit numbers and then put them together into one 64 bit number creating a very fast and even spread of hashed numbers.

Prime and offsets

32 bit
Prime: 16777619 offset: 2166136261
64 bit
Prime: 1099511628211 offset: 14695981039346656037

Here is a page on FNV that is a good source of information.

NSA has released Cryptol

 Cryptol is a language used to specify, implement, test and verify cryptographical algorithms. I have just taken a first glance at it and it seems really competent. All cryptography buffs out there should rejoice over this tool.

Cryptol can further ”compile” your cryptographic algorithms into languages such as VHDL, C and Haskell. You may download a trial version for non-commercial uses from the galois site.