* @const scaf_piece *mu@ = scaled approximation to @1/l@
* @size_t npiece@ = number of pieces in @l@
* @unsigned piecewd@ = nominal width of a piece in bits
* @const scaf_piece *mu@ = scaled approximation to @1/l@
* @size_t npiece@ = number of pieces in @l@
* @unsigned piecewd@ = nominal width of a piece in bits