How is the target section of a block header calculated?

[Bitcoin]

How is the target section of a block header calculated?

I've been poking around https://en.bitcoin.it/wiki/Target and I've found the current target, but I can't seem to find how it's generated. It's supposedly generated when the difficulty is adjusted, as stated here: https://en.bitcoin.it/wiki/Block_hashing_algorithm, but what exactly is the algorithm for generating the target? If someone could show me some psuedocode that would be great.

Source: How is the target section of a block header calculated?