- *
- * We can detect ghosting in a single pass (*) over the keyboard state
- * by maintaining two arrays. pressed_in_row counts how many pressed
- * keys we have found in a row. row_has_teeth is true if any of the
- * pressed keys for this row has other pressed keys in its column. If
- * at any point of the scan we find that a row has multiple pressed
- * keys, and at least one of them is at the intersection with a column
- * with multiple pressed keys, we're sure there is ghosting.
- * Conversely, if there is ghosting, we will detect such situation for
- * at least one key during the pass.
- *
- * (*) This looks linear in the number of keys, but it's not. We can
- * cheat because the number of rows is small.