10-11. Miscellaneous Topics (Unsigned)
Theorem DC2U. The least multiplier m is odd if p is not forced to equal W.
Theorem DC3U. For a given divisor d, there is only one multiplier m having the minimal value of p, if p is not forced to equal W.
The proofs of these theorems follow very closely the corresponding proofs for signed division.
The Divisors with the Best Programs (Unsigned)
For unsigned division, to find the divisors (if any) with optimal programs of two instructions to obtain the quotient (li, mulhu), we can do an analysis similar to that of the signed case (see “The Divisors with the Best Programs” on page 175). The result is that such divisors are the factors of 2W or 2W + 1, except for d = 1. For the common word sizes, this leaves ...
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