Custom Exponents

[Malkierian]

Alright, so I'm trying to do hex string to integer conversion, 
but I can't for the live of me find how to do exponent 
calculation in D.  Java has a Math.pow() function that allows you 
to specify the base and the exponent, but all I've seen in D's 
libraries are functions that allow you to only specify the 
exponent and does it on a predetermined base, such as 2, e or 10. 
  I need 16 for the base.