Men-at-arms counters calculator

For each base type T on one side:

counter points = Σ (sub-regiments of each enemy regiment × its "counters" value for T)
needed         = 2 × sub-regiments of type T
damage cut     = 0.9 × min(1, counter points ÷ needed)

From the game's combat defines (NCombat in game/common/defines/00_defines.txt): MEN_AT_ARMS_MAX_COUNTER = 0.9 — “when RATIO_FOR_MAX_COUNTER is hit, the damage output for the MaA will be reduced by this much. For values lower, it'll be linear”; and RATIO_FOR_MAX_COUNTER = 2 — “you need this many effective regiment chunks to counter a single regiment chunk. Modified by counter effectiveness”. A regiment is made of sub-regiments (chunks) of the regiment's stack size; it has REGIMENT_DEFAULT_MAX_SIZE = 3 before size bonuses, and new regiments here start at that size.

Damage and toughness totals are the base stat × soldiers; levies count 10 damage and 10 toughness each (LEVY_ATTACK, LEVY_TOUGHNESS). Not modelled: commanders, knights, terrain, innovations, buildings, advantage, damaged regiments (all sub-regiments count as full) and the battle phases. Siege weapons are left out (they don't fight in the main phase).