Programmable High Performance Data Communication Adapter for High Speed Packet Transmission Networks

1. A line adapter (401, 402) for a switching node (300) in a packet communication network (200) including: a programmable processing means (SSP) for receiving (138) and transmitting (137) data packets of fixed or variable length; memory means having a plurality of buffers (132,800) for storing said data packets and a separate area (131) for working storage; means for identifying said data packets in said buffers including; buffer pointers (B.sub.-- PTR) each identifying one of the said data packet buffers, said buffer pointers including a status field for indicating when the pointed to buffer contains the end of a packet (EOP) or the end of a segment (EOS), a free buffer list (FBL) and an associated free buffer list pointer (P.sub.-- FBL) for identifying said list, said list including indicia indicating buffers which are free and available for use in storing packets, buffer lists (B.sub.-- LIST) each including a plurality of buffer pointers (B.sub.-- PTR) each identifying a buffer in the memory in which packet data is stored, packet pointers (P.sub.-- PTR) for identifying a said buffer list (B.sub.-- LIST), at least one list of packet pointers (P.sub.-- LIST), and queue pointers (Q.sub.-- PTR) for identifying a said packet pointer list (P.sub.-- LIST); means responsive to the detection of the end of segment (EOS) status for correlating buffers of the same packet having buffer pointers (B-PTR) in different buffer lists (B-LIST), whereby buffer lists (B-LIST) can be of uniform size or smaller than needed to accommodate the largest packet; means (FIG. 15) for listing said identifying means in said working storage (131) in a single instruction; means (FIG. 14) for delisting said identifying means in said working storage in a single instruction; and, means responsive to the delisting of a buffer for modifying the indicia in the free buffer list (FBL) to indicate the availability of the buffer.

2. The programmable adapter set forth in claim 1 in which each of the lists includes a prefix for storing information related to the data included in the list.

3. The programmable adapter set forth in claim 2 in which the said buffer list prefix includes control and routing information from the header of the stored data packet.

4. The programmable adapter set forth in claim 3 in which the listing and delisting means can have up to three operations executing in parallel.

5. The programmable adapter set forth in claim 1 in which said list pointers include: a first field identifying the list (LID); a second field identifying where (TAIL) to attach a pointer to the list; and, a third field identifying the first pointer (HEAD) in the list.

6. The programmable adapter set forth in claim 1 in which each buffer pointer includes in addition to said status field: a first field for identifying a buffer (BID); a second field for identifying the first data element (FEP) in said buffer; a third field for identifying the last data element (LEP) in said buffer; and, a fourth field for identifying a current data element (CEP) in said buffer.

7. The programmable adapter set forth in claim 6 in which: the buffer lists are of fixed length; the buffer pointers can be chained in a plurality of buffer lists when a stored data packet requires more buffers than a single fixed length buffer list can accommodate; and, said status indicator is set in the last buffer pointer of each buffer list to ensure a correlation between the different lists of the said data packet.

8. A method of handling data packets in a line adapter (401, 402) for a switching node (300) in a packet communication network (200) which includes a memory, a programmable processing means (SSP) for receiving (138) and transmitting (137) data packets of fixed or variable length, said method including the following steps: dividing said memory into a plurality of buffers (132,800) for storing said data packets and a separate area (131) for working storage; establishing pointers and lists in the working storage for identifying said data packets in said buffers including; buffer pointers (B.sub.-- PTR) each identifying one of the said data packet buffers, said buffer pointers including a status field for indicating when the pointed to buffer contains the end of a packet (EOP) or the end of a segment (EOS), a free buffer list (FBL) and an associated free buffer list pointer (P.sub.-- FBL) for identifying said list, said list including indicia indicating which buffers are free and available for use in storing packets, buffer lists (B.sub.-- LIST) each including a plurality of buffer pointers (B.sub.-- PTR) each identifying a buffer in the memory in which packet data is stored, packet pointers (P.sub.-- PTR) for identifying a said buffer list (B.sub.-- LIST), queue pointers (Q.sub.-- PTR) for identifying a said packet pointer list (P.sub.-- LIST); detecting the end of segment (EOS) status for correlating buffers of the same packet having buffer pointers (B-PTR) in different buffer lists (B-LIST), whereby buffer lists (B-HST) can be of uniform size or smaller than needed to accommodate the largest packet; listing said identifying means (FIG. 15) in said working storage (131) in a single instruction; delisting said identifying means (FIG. 14) in said working storage in a single instruction; and, modifying the indicia in the free buffer list (FBL) to indicate the availability of the buffer following the delisting of a buffer.

9. The method set forth in claim 8 in which each of the lists includes a prefix for storing information related to the data included in the list.

10. The method set forth in claim 9 in which the said buffer list prefix includes control and routing information from the header of the stored data packet.

11. The method set forth in claim 8 in which the listing and delisting step can have up to three operations executing in parallel.

12. The method set forth in claim 8 in which said list pointers include: a first field identifying the list (LID); a second field identifying where (TAIL) to attach a pointer to the list; and, a third field identifying the first pointer (HEAD) in the list.

13. The method set forth in claim 8 in which each buffer pointer includes in addition to said status field: a first field for identifying a buffer (BID); a second field for identifying the first data element (FEP) in said buffer; a third field for identifying the last data element (LEP) in said buffer; and, a fourth field for identifying a current data element (CEP) in said buffer.

14. The method set forth in claim 13 in which: the buffer lists are of fixed length; the buffer pointers can be chained in a plurality of buffer lists when a stored data packet requires more buffers than a single fixed length buffer list can accommodate; and, said status indicator is set in the last buffer pointer of each buffer list to ensure a correlation between the different lists of the said data packet.