[PATCH] Another tweak to the multiplication algorithm

[Joseph S. Myers]

On Wed, 13 Feb 2013, Siddhesh Poyarekar wrote:

> Hi,
> 
> This is a second tweak to the mpa multiplication algorithm, which is
> based on the Karatsuba algorithm[1].  This reduces multiplication
> instructions in favour of additions and halves the number of
> iterations required in calculating a single mantissa digit.  Joseph

The point of Karatsuba is not achieving a factor-2 reduction, but using 
recursion to reduce the time required for multiplying numbers of 2^n 
digits (n large enough for this to be worthwhile) from 4^n to 3^n.  I 
don't see obvious recursion here....

-- 
Joseph S. Myers
joseph@codesourcery.com