System and method for transferring data over an external transmission medium

• US 7,043,565 B1
• Filed: 08/11/2000
• Issued: 05/09/2006
• Est. Priority Date: 08/11/2000
• Status: Expired due to Term

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Vrancic, Aljosa, Madden, David W.
• Primary Examiner(s): Dinh, Dung C.
• Assistant Examiner(s): PARTON, KEVIN S
• Application Number:
  US09/638,051
• Time in Patent Office: 2,097 Days
• Field of Search: 709200-202, 709/217, 709/223, 709/226, 709/230, 709/236, 709/231, 709/250, 710/6, 710/33, 710/55, 719/310, 719/316, 719/321, 718/100
• US Class Current: 709/250
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling

Abstract

A system and method for transferring data over an external transmission medium. A host computer is coupled to a device through a serial bus. A transfer object is configurable to encapsulate data transfer-related functionality, providing a generic interface for transmission of data over a variety of external transmission media and protocols. A user makes one or more transfer requests. Transfer objects corresponding to each request are built and linked together to form a sequential chain. The requests of the transfer objects are executed sequentially. If the current transfer object is the first in the chain, the request is executed on a current thread at passive level or higher, otherwise the request is executed on a system (kernel) thread at dispatch level. When a response to the request returns, control is returned to the current transfer object. The process is repeated until all transfer objects are processed.

Claims

1. A method for transferring data over an external transmission medium, the method comprising:

receiving a plurality of transfer requests;

building a chain of transfer objects, wherein each transfer object corresponds to one of the plurality of transfer requests, wherein said building the chain of transfer objects includes linking the plurality of transfer objects together sequentially; and

sequentially performing the request of each transfer object in the chain of transfer objects, wherein said sequentially performing the request of each transfer object in the chain of transfer objects comprises performing a request of a current transfer object;

wherein said performing the request of the current transfer object is executed on a first thread at passive level if the current transfer object is the first transfer object in the chain; and

wherein said performing the request of the current transfer object is executed on a system thread at kernel-dispatch level if the current transfer object is not the first transfer object in the chain.

2. The method of claim 1, wherein the building the chain of transfer objects comprises:

creating a plurality of transfer objects; and

attaching a user callback function to zero or more of the plurality of transfer objects.

3. The method of claim 2, wherein said creating the plurality of transfer objects comprises:

allocating memory for each of the plurality of transfer objects;

populating each of the plurality of transfer objects with transfer information, wherein the transfer information comprises one or more transfer types;

allocating memory for a plurality of request block objects, wherein each of the plurality of request block objects corresponds to one of the plurality of transfer objects, wherein each of the request block objects is comprised in a corresponding one of the transfer objects, and wherein each of the request block objects provides an operating system-independent and bus-independent interface which encapsulates operating system-dependent and bus-dependent data; and

populating each of the plurality of request blocks with operating system-dependent and bus-dependent information related to a request of a corresponding transfer object.

4. The method of claim 3, wherein the one or more transfer types comprise one or more of a read transfer, a write transfer, a single point transfer, a block transfer, a synchronous transfer, an asynchronous transfer, a random read transfer, or a random write transfer.

5. The method of claim 1, wherein said sequentially performing the request of each transform object in the chain of transfer objects reduces passive/dispatch level transitions.

6. The method of claim 1, wherein said sequentially performing the request of each transform object in the chain of transfer objects reduces user/kernel mode transitions.

7. The method of claim 1, wherein said sequentially performing the request of the current transform object further comprises:

executing a static callback function to return control to the current transfer object on the system thread at kernel dispatch level;

executing a first callback function of the current transfer object to complete the request on the system thread at kernel dispatch level;

executing the first callback function of the current transfer object to set an event on the system thread at kernel dispatch level, wherein the event signals completion of the request;

determining if there is a user callback function attached to the current transfer object; and

executing the user callback function on the system thread at kernel dispatch level if there is a user callback function attached to the current transfer object.

8. The method of claim 7,

wherein said performing the request of the first transfer object on the first thread at passive level comprises performing the request of the first transfer object on the first thread at kernel-passive level.

9. The method of claim 7,

wherein said performing the request of the first transfer object on the first thread at passive level comprises performing the request of the first transfer object on the first thread at user-passive level.

10. The method of claim 7, further comprising:

a last transfer object in the chain calling a wait function on the first thread after the performing the request of the first transfer object in the chain of transfer objects, wherein the calling the wait function on the first thread puts the first thread into a sleep mode;

wherein the first thread is awakened from the sleep mode in response to the current transfer object setting an event on the system thread at kernel dispatch level, wherein the event signals completion of the request; and

wherein the current transfer object is the last transfer object in the chain.

11. The method of claim 1,

wherein said external transmission medium comprises an IEEE 1394 bus, wherein said IEEE 1394 bus is implemented in accordance with an IEEE 1394 protocol specification.

12. The method of claim 1,

wherein said external transmission medium comprises a Universal Serial Bus (USB) bus.

13. The method of claim 1,

wherein said external transmission medium uses the Ethernet protocol.

14. A system for transferring data, the system comprising:

a host system including a processor and memory, wherein the memory stores data and driver software, and wherein the processor is operable to execute the driver software;

an external communications medium; and

a device, wherein the device is coupled to the host system through the external transmission medium;

wherein the driver software is executable to receive a plurality of transfer requests, build a chain of transfer objects, and submit the chain of transfer objects for execution by the host system;

wherein each of the plurality of transfer objects corresponds to one of the plurality of transfer requests, and wherein each of the transfer objects is operable to perform a request to read from or write to the device; and

wherein the host system is operable to perform the request of each transfer object in the chain of transfer objects sequentially, wherein the request of the first transfer object in the chain of transfer objects is executed on a thread at passive level, and wherein the requests of subsequent transfer objects in the chain of transfer objects are executed on one or more system threads at kernel-dispatch level.

15. The system of claim 14,

wherein each of the plurality of transfer objects comprises:

transfer information, wherein the transfer information includes one or more transfer types;

a request block object, wherein the request block object provides an operating system-independent and bus-independent interface which encapsulates operating system-dependent and bus-dependent data related to a request of a corresponding transfer object, and wherein the request block object implements the external communications medium protocol in an operating system specific data structure;

a link which is operable to provide access to another transfer object;

an intrinsic callback function; and

a static callback function.

16. The system of claim 15,

wherein one or more of the plurality of transfer objects each further comprises a user callback function.

17. The system of claim 14,

wherein the software being executable to build a chain of transfer objects includes the software being executable to:

allocate memory for each of the plurality of transfer objects;

populate each of the plurality of transfer objects with transfer information which comprises one or more transfer types;

allocate memory for a plurality of request blocks, wherein each of the plurality of request blocks corresponds to one of the plurality of transfer objects, and wherein each of the request blocks is comprised in a corresponding one of the transfer objects, wherein each of the request block objects provides an operating system- and bus-independent interface which encapsulates operating system- and bus-dependent data;

populate each of the plurality of request blocks with operating system- and bus-dependent information relating to the request of the transfer object;

attach a user callback function to zero or more of the plurality of transfer objects; and

chain the plurality of transfer objects together sequentially.

18. The system of claim 14,

wherein the host system being operable to perform the request of each transform object in the chain of transfer objects sequentially comprises the host system being operable to perform a request of a current transfer object on a first thread at passive level if the current transfer object is the first transfer object in the chain;

and perform the request of the current transfer object on a system thread at kernel-dispatch level if the current transfer object is not the first transfer object in the chain.

19. The system of claim 18, wherein the host system being operable to perform the request of the current transfer object further comprises the host system being operable to:

execute a static callback function to return control to the current transfer object on the system thread at kernel dispatch level;

execute the intrinsic callback function of the current transfer object to complete the request on the system thread at kernel dispatch level;

execute the intrinsic callback function of the current transfer object to set an event on the system thread at kernel dispatch level, wherein the event signals completion of the request;

determine if there is a user callback function attached to the current transfer object;

execute the user callback function of the current transfer object on the system thread at kernel dispatch level if there is a user callback function attached to the current transfer object.

20. The system of claim 18,

wherein the host system being operable to perform the request of the first transfer object on the first thread at passive level comprises the host system being operable to perform the request of the first transfer object on the first thread at kernel-passive level.

21. The system of claim 18,

wherein the host system being operable to perform the request of the first transfer object on the first thread at passive level comprises the host system being operable to perform the request of the first transfer object on the first thread at user-passive level.

22. The system of claim 18,

wherein the host system is further operable to execute a wait function of a last transfer object in the chain on the first thread after the performing the request of the first transfer object in the chain of transfer objects, wherein the executing the wait function of the last transfer object in the chain on the first thread puts the first thread into a sleep mode;

and

wherein the first thread is awakened from the sleep mode in response to d) executing the intrinsic callback function of the current transfer object to set an event on the system thread at kernel dispatch level, wherein the event signals completion of the request, and wherein the current transfer object is the last transfer object in the chain.

23. The system of claim 14,

wherein the host system comprises a computer system.

24. The system of claim 14, wherein the one or more transfer types comprise one or more of a read transfer, a write transfer, a single point transfer, a block transfer, a synchronous transfer, an asynchronous transfer, a random read transfer, or a random write transfer.

25. The system of claim 14,

wherein said external transmission medium comprises an IEEE 1394 bus, and wherein said IEEE 1394 bus is implemented in accordance with an IEEE 1394 protocol specification.

26. The system of claim 14,

wherein said external transmission medium comprises a Universal Serial Bus (USB) bus.

27. The system of claim 14,

wherein said external transmission medium uses the Ethernet protocol.

28. The system of claim 14,

wherein the driver software comprises data acquisition driver software, and wherein the device comprises a data acquisition device.

29. The system of claim 14, further comprising a toolbox stored in the memory of the host computer, wherein the toolbox is operable to provide a generic interface to manage communications between drivers.

30. A transfer object, wherein the transfer object is configurable to encapsulate data transfer-related functionality to provide a generic interface for transmission of data over a variety of external transmission media and protocols, comprising:

transfer information, wherein the transfer information includes one or more transfer types;

a request block object, wherein the request block object provides an operating system-independent and bus-independent interface which encapsulates operating system-dependent and bus-dependent data related to a data transfer request, and wherein the request block object implements the external transmission medium protocol in an operating system specific data structure;

a link which is operable to provide access to another transfer object, wherein the link provides a mechanism for chaining transfer objects together;

an intrinsic callback function which is operable to execute a transaction to complete the data transfer request, and which is further operable to set an event signaling completion of the data transfer request; and

a static callback function.

31. The transfer object of claim 30, further comprising:

a user callback function, wherein the user callback function is operable to execute a user-specified task after the data transfer request of the transfer object has been executed.

32. The transfer object of claim 30, wherein the one or more transfer types comprise one or more of a read transfer, a write transfer, a single point transfer, a block transfer, a synchronous transfer, an asynchronous transfer, a random read transfer, or a random write transfer.