18.104.22.168. Vertical Symmetry
The FIR Filter IP has 1 axis of symmetry across a horizontal line through the center tap in the 2D coefficient array.
In this case, the number of horizontal taps (N) may be even or odd, but the number of vertical taps (M) must be odd. Vertical symmetry offers only N×((M+1)/2) unique coefficient values, with the remaining values in the array being mirrored duplicates.
With run-time control of the coefficients, the register map only includes addresses to update the N×((M+1)/2) unique coefficient values, indexed for an example 5×5 array.