Base B multiplication without conversion

[candide]

Hi,
I'm a beginner-user of gmp. I wish to multiply two "big integers" x and
y, each represented in base B
(typically 2<=B<=256) by an array  of digits (each base B digit being
represented by a
decimal integer less than B).

I was wondering if some GMP trick can compute "directly" the base B
digits of the
result x*y  ("directly" here means : without using a radix conversion) ?

A very short example for illustration purpose should be very appreciated.

Thanks.