Request for multiplicative inverse function

[szigetij]

Request for multiplicative inverse function

[SzigetiJ]

I do not know the exact term, maybe called better multiplicative complement, as
(x0,x1) = dmul(a,q), and add-with-carry m to x results in x0: 0 (low) and x1: 1 (hi) values.

The multiplicative complement of 0 does not exist, as we cannot find any q, m pair that fulfills this requirement.

Quick example values with max=15 (4-bit uint):

  a |  q |  m
----+----+----
  0 |  x |  x
  1 | 15 |  1
  2 |  8 |  0
  3 |  5 |  1
  4 |  4 |  0
  5 |  3 |  1
  6 |  2 |  4
  7 |  2 |  2
  8 |  2 |  0
  9 |  1 |  7
 10 |  1 |  6
 11 |  1 |  5
 .. | .. | ..

[SzigetiJ]

Maybe in another, Modular Arithmetic project.