  In this paper, we present a universal scheme for transforming an arbitrary
algorithm for biased 2-face coins to generate random bits from the general
source of an m-sided die, hence enabling the application of existing algorithms
to general sources. In addition, we study approaches of efficiently generating
a prescribed number of random bits from an arbitrary biased coin. This
contrasts with most existing works, which typically assume that the number of
coin tosses is fixed, and they generate a variable number of random bits.
