http://benji3up2kxewkqfcq7buxk2xd6zwy3zggnurkrm3l4cvwy2iipvyyad.onion/mirrors/gmpdoc/Binary-to-Radix.html
Something similar would
work for the sub-quadratic divisions too, though there would be the cost of
calculating a bigger radix power. Another possible improvement for the sub-quadratic part would be to arrange
for radix powers that balanced the sizes of quotient and remainder produced,
i.e. the highest power would be an b^(n*k) approximately equal to sqrt(t) , not restricted...