Minimum-latency data mover with auto-segmentation and reassembly

• US 5,949,799 A
• Filed: 12/27/1996
• Issued: 09/07/1999
• Est. Priority Date: 12/27/1996
• Status: Expired due to Term

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Grivna, Edward L., Scott, Paul
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): MARC, MCDIEUNEL
• Application Number:
  US08/777,304
• Time in Patent Office: 984 Days
• Field of Search: 371/33, 370/4 R, 370/341, 370/403, 370/229, 370/401, 370/405, 370/402, 370/258, 370/352, 370/464, 395/200.8, 395/828, 395/309, 395/286, 395/680, 395/200.61, 395/200.08, 395/733, 463/29
• US Class Current: 714/749
• CPC Class Codes: H04L 1/1664 the supervisory signal being transmitted together with payload signals; piggybacking
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 1/1835 Buffer management
• CPC Class Codes: H04L 1/1874 Buffer management

Abstract

A data mover which provides guaranteed transfer of data between two locations. The data mover includes a pair of data packet memories for input, a pair of data packet memories for output, and a controller which alternately switches each of the paired data packet memories between a data loading mode and a data unloading mode. The controller enables one of the paired data packet memories in the data loading mode and enables the other one of the paired data packet memories in the data unloading mode. The controller switches the modes of the paired data packet memories upon receiving an acknowledgement of moved data. By (a) switching the paired data packet memories upon receiving the acknowledgement, (b) segmenting the data packets (enabling data transfer initiation before all source data becomes available) and/or (c) embedding a response (enabling transmission of the next packet without first waiting for complete transmission of an incoming packet), complete transmission of the bi-directional data is automatically segmented and reassembled to minimize latency.

Claims

1. A data mover for moving a plurality of data packets between a first host and a second host, said data mover comprising:

first and second transmit data packet memories each configured to hold one of said plurality of data packets at a time;

a transmitter for transmitting data to the second host; and

a controller in communication with said first and second transmit data packet memories and said transmitter, said controller for alternately enabling one of said first and second transmit data packet memories to receive a first one of said data packets from the first host while enabling the other of said first and second transmit data packet memories to transfer a second one of said data packets to said transmitter.

2. The data mover according to claim 1, wherein said controller is configured to alternate said first and second transmit data packet memories in response to acknowledgment of the receipt of said first one of said data packets.

3. The data mover according to claim 2, wherein said acknowledgment is embeddable within said data packets.

4. The data mover according to claim 1, wherein said controller is adapted to cause a respective one of said first and second transmit data packet memories to retransfer a respective data packet to said transmitter in response to a negative acknowledgment of one of said data packets.

5. The data mover according to claim 4, wherein said negative acknowledgment is embeddable within one of said data packets.

6. The data mover according to claim 1, wherein said data packets comprise one or more data characters, and said controller is configured to embed one or more differentiation characters distinct from said data characters within the data packets.

7. The data mover according to claim 1, wherein said controller is adapted to monitor said data packets and embed a plurality of differentiation characters within the data packets.

8. The data mover according to claim 1, further comprising a bulk data memory to buffer data between said first and second transmit data packet memories and the first host.

9. The data mover according to claim 1, wherein said first and second transmit data packet memories are FIFO memories.

10. The data mover according to claim 1, further comprising a receiver for receiving data from the second host and first and second receive data packet memories, wherein said controller is in communication with said first and second receive data packet memories for alternately enabling said first receive data packet memory to load data packets from said receiver while enabling said second receive data packet memory to transfer a validated data packet to said first host.

11. The data mover according to claim 10, wherein said controller is adapted to alternate said first and second receive data packet memories in response to said validated data packet.

12. The data mover of claim 11, wherein said controller acknowledges the receipt of said data packets in response to said validated data packet.

13. The data mover according to claim 11, wherein said acknowledgment is embeddable within the data packets.

14. The data mover according to claim 10, further comprising a bulk data memory to buffer receive data between said first and second receive data packet memories and the first host.

15. The data mover according to claim 10, wherein said first and second receive data packet memories are FIFO memories.

16. The data mover according to claim 1, wherein said first and second transmit data packet memories are configured to segment said plurality of data packets.

17. The data mover according to claim 1, wherein said data mover is configured to operate independently of a second plurality of data packets configured to operate at a host level.

18. The data mover according to claim 1, wherein said first and second transmit data packets are configured to be alternately enabled without waiting for a predetermined amount of data to be received from said first or second host.

19. The data mover according to claim 1, wherein said first and second transmit data packets are configured to be alternately enabled without waiting for the first transmit data packet memory to be full before starting to transfer data from the second transmit data packet memory.

20. The data mover according to claim 1, further comprising a bulk data memory connected between said first and second transmit data packet memories and said first or second host, wherein said bulk data memory is configured to change the clock domain of the data packets.

21. The data mover according to claim 1, wherein said first and second transfer data packet memories are configured to allow simultaneous loading and unloading operations.

22. The data mover according to claim 1, wherein said first and second transmit data packet memories are configured to automatically segment said plurality of data packets.

23. A system comprising:

a first and second host;

a serial link interconnecting said first and second hosts;

first and second data movers respectively connecting said first and second hosts with said serial link, each of said data movers including first and second transmit data packet memories, a transmitter for transmitting data over said serial link, and a controller in communication with said first and second transmit data packet memories and said transmitter, said controller for alternately enabling one of said first and second transmit data packet memories to receive a first one of a plurality of data packets while enabling the other of said first and second transmit data packet memories to transfer a second one of said data packets to said transmitter, wherein said first and second data packet memories are each configured to hold one of said plurality of data packets at a time.

24. The system according to claim 23, wherein said controller is configured to alternate said first and second transmit data packet memories in response to an acknowledgment of one of said data packets.

25. The system according to claim 24, wherein said acknowledgment is embeddable within said data packets received by said first or second transmit data packet memories.

26. The system according to claim 23, wherein said controller is configured to enable retransferring a respective transmit data packet to said transmitter in response to a negative acknowledgment of one or more of said data packets.

27. The system according to claim 26, wherein said negative acknowledgment is embeddable within said data packets.

28. The system according to claim 25, wherein at least one of said data packets comprise one or more data characters, and said controller is configured to embed one or more differentiation characters distinct from said data characters within the data packet received by said first or second transmit data packet memories.

29. The system according to claim 23, wherein said controller is adapted to monitor the data packets and embed a plurality of differentiation characters within the data packets.

30. The system according to claim 23, further comprising a bulk data memory to buffer data between at least one of said hosts and the associated transmit data packet memory.

31. The system according to claim 23, wherein said first and second hosts each comprise bulk data memory to buffer data between said hosts and said data movers.

32. The system according to claim 23, wherein each of said data movers further comprise (a) a receiver for receiving data from said serial link and (b) first and second receive data packet memories, wherein said controller is in communication with said first and second receive data packet memories for alternately enabling said first receive data packet memory to load one of said data packets from said receiver while enabling said second receive data packet memory to transfer a validated data packet.

33. The system according to claim 32, wherein said controller is adapted to alternate said first and second receive data packet memories in response to an acknowledgment of one of said data packets.

34. The system according to claim 33, wherein said acknowledgment is embeddable within the data packets.

35. The system according to claim 32, wherein each of said data movers further comprise a bulk data memory to buffer data between said first and second data packet memories and the associated one of said hosts.

36. A method for moving a plurality of data packets between a first host and a second host, said method comprising the steps of:

enabling a first data packet memory, configured to hold one of said plurality of data packets at a time, to a loading mode wherein a first data packet from the first host is loaded;

enabling a second data packet memory, configured to hold one of said plurality of data packets at a time, to an unloading mode wherein a second data packet is unloaded for transmission to the second host;

transmitting the second data packet; and

alternating the modes of the first and second data packet memories.

37. The method according to claim 36, wherein said step of alternating the modes responds to an acknowledgment of one of said data packets.

38. The method according to claim 37, further comprising the step of embedding the acknowledgment in said data packet.

39. The method according to claim 36, further comprising the step of retransmitting the second data packet in response to a negative acknowledgment of one of said data packets.

40. The method according to claim 39, further comprising the step of embedding the negative acknowledgment in one of said data packets.

41. The method according to claim 36, further comprising embedding one or more differentiation characters distinct from said data characters within the one of said data packets.

42. The method according to claim 41, wherein the step of embedding one or more differentiation characters is in response to the receipt of one of said data packets.

43. A data mover for moving a plurality of data packets between a first host and a second host, said data mover comprising:

first and second receive data packet memories each configured to hold one of said plurality of data packets at a time;

a transmitter for transmitting data to the second host; and

a controller in communication with said first and second receive data packet memories and said transmitter, said controller for alternately enabling one of said first and second receive data packet memories to receive a first one of said data packets from the first host while enabling the other of said first and second receive data packet memories to transfer a second one of said data packets to said transmitter.