Puyo Puyo Tetris movement intricacies

Inter-frame processing order
Here are a few tests conducted to reverse-engineer the order in which inputs are handled:
 * Left + right simultaneously - piece shifts right
 * Left + harddrop - piece hard drops, no shift
 * Rotate + harddrop - piece rotates then hard drops

Using this test data, we can assume that input is processed in this order:
 * Rotation
 * Hard drop
 * Shifting
 * ? Where DAS/Auto-shifting occurs is unknown at this point

Entry Delay / ARE

 * DAS can be charged during Entry Delay
 * Hard drop inputs during Entry Delay are ignored
 * Tapping Left/Right inputs during Entry Delay are ignored (however, the keyheld event is processed - DAS can be charged)
 * Hold inputs during Entry Delay ignored
 * Rotation inputs during Entry Delay are ignored

DAS Double-Charging
DAS is charged on two separate counters. It is possible to charge both DAS counters at once.

E.g.
 * DAS first piece to right wall. Drop
 * Hold left, do not release right.
 * Das second piece to left wall. Drop. (Left and Right DAS are both charged)
 * Release left key. Piece will go right with DAS Charged.