Terminating apparatus for ATM adaptation layer

A terminating apparatus of an ATM adaptation layer for terminating received cells, connection by connection, and assembling an ATM adaptation layer message for each connection from data contained in the received cells, comprising:

• a header extraction means for extracting a virtual path indication/virtual channel indication (VPI/VCI) from a received cell;
• a CRC means shared by “of the ATM adaptation layer message to perform a CRC calculation for the payload data of the received cell” different connections;
• a reception process means for determining, based on a payload type indication contained in the header of the received cell, whether or not the received cell is the last cell of an ATM adaptation layer message prepared for a connection related to the received cell and processing the received cell;
• a work memory for storing, for each connection, a CRC result and the number of received cells;
• and
• a reception buffer for sequentially storing, for each connection, data extracted from the received cells;
• wherein
• the work memory has, for each connection, a part for storing an address of the reception buffer where the latest data received for the connection is stored;
• and, when a cell related to the connection is received,
• the reception process means reads the stored address and stores data extracted from the received cell related to the connection into the reception buffer at an address just after the read address.

A terminating apparatus of an ATM adaptation layer for terminating received cells, connection by connection, and assembling an ATM adaptation layer message for each connection from data contained in the received cells, comprising:

• a header extraction means for extracting a virtual path indication/virtual channel indication (VPI/VCI) from a received cell;
• a CRC means shared by “of the ATM adaptation layer message to perform a CRC calculation for the payload data of the received cell” different connections;
• a reception process means for determining, based on a payload type indication contained in the header of the received cell, whether or not the received cell is the last cell of an ATM adaptation layer message prepared for a connection related to the received cell and processing the received cell;
• a work memory for storing, for each connection, a CRC result and the number of received cells;
• and
• a reception buffer for sequentially storing, for each connection, data extracted from the received cells;
• wherein
• the reception process means determines whether the received cell is at the start, or in the middle, or at the end of the corresponding connection according to the determination whether or not the received cell is the last cell of the ATM adaptation layer message prepared for the corresponding connection, updates a CRC result and the number of received cells of the corresponding connection in the work memory, and processes a payload of the received cell;
• and
• the apparatus further has DMA control means for transferring, for each connection, a CRC result between the CRC means and the work memory according to a VPI/VCI extracted by the header extraction means and transferring data extracted from a received cell to the reception buffer according to an instruction from the reception process means.