Cyclic buffer management

• US 7,788,463 B2
• Filed: 02/13/2007
• Issued: 08/31/2010
• Est. Priority Date: 02/13/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Cooper, Kenneth H.
• Primary Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US11/674,439
• Publication Number:
  US 20080195838A1
• Time in Patent Office: 1,295 Days
• Field of Search: None
• US Class Current: 711/203
• CPC Class Codes: G06F 12/10 Address translation

Abstract

Systems and methods for cyclic buffer management are described. In one aspect, the systems and methods enable cyclic buffer wrap-around write operations independent of temporary buffer allocations and corresponding multiple data copies. To this end, the systems and methods map the cyclic buffer'"'"'s physical addresses two-times (“doubly map”) to a consecutive block of virtual memory. When an application desires to write beyond the end of what represents the cyclic buffer, the systems and methods provide a logical pointer to the doubly mapped virtual memory, enabling the application to directly write into the virtual memory from the end of the first cyclic buffer mapping to the beginning of the second cyclic buffer mapping. The memory management operations automatically transfer the data out of this doubly mapped virtual memory into the cyclic buffer for subsequent extraction and presentation to the user.

Claims

1. A computer-implemented method for cyclic buffer management, the method comprising:

doubly mapping physical addresses associated with a cyclic buffer of tangible memory to logical addresses to create doubly mapped virtual memory, the doubly mapped virtual memory comprising;

two different logical addresses for each physical address of the cyclic buffer; and

a fist virtual mapping of the cyclic buffer to a first virtual memory block and a second virtual mapping of the cyclic buffer to a second virtual memory block, the first virtual memory block and the second virtual memory block being consecutive in the virtual memory;

enabling a client application to write in a single data transfer directly into the doubly mapped virtual memory independent of whether logical addresses being written into correspond to physical addresses corresponding to an end of the cyclic buffer and a beginning of the cyclic buffer;

and

wherein the data and the cyclic buffer is for extraction and presentation in a data stream to a user.

2. The method of claim 1, wherein an end portion of the first virtual mapping is page aligned with a beginning portion of the second virtual mapping.

3. The method of claim 1, wherein the client application is an audio streaming application.

4. The method of claim 1, wherein enabling the client application to write directly into the doubly mapped virtual memory further comprises communicating a logical memory address pointer to the client indication, the logical memory address pointer indicating a current position in the doubly mapped virtual memory to write data.

5. The method of claim 1, wherein the method further comprises:

receiving a request from the client application to allocate the cyclic buffer; and

.

responsive to receiving the request, allocating the cyclic buffer via a device driver.

6. The method of claim 1, wherein the method further comprises transferring data from consecutive logical addresses in the doubly mapped virtual memory into the cyclic buffer, the consecutive logical addresses sequentially corresponding to a last physical address of the cyclic buffer and a first physical address of the cyclic buffer.

7. The method of claim 1, wherein the method further comprises streaming the data from the cyclic buffer for presentation to a user.

8. A tangible computer-readable medium comprising computer-executable instructions for cyclic buffer management, the computer-textual instructions comprising instructions for:

allocating a cyclical buffer in physical memory for audio streaming;

mapping a first address and a second address of the cyclical buffer to a first virtual memory block and a second virtual memory block, the first virtual memory block and the second virtual memory block being consecutive in a virtual memory and page aligned;

responsive to request from an audio application to write an amount of data into the cyclical buffer that will wrap around the end of the cyclical buffer to the beginning of the cyclical buffer, allowing the audio application to write the amount of data directly in a single data transfer into the first virtual memory block and the second virtual memory block independent of temporary buffer allocation and data copies; and

wherein the amount of data is automatically transferred out of the first and second virtual memory blocks into the cyclical buffer for extraction and presentation in an audio stream to a user.

9. The computer-readable medium of claim 8, wherein the computer-executable instructions for allowing the audio application to write directly into the doubly mapped virtual memory further comprise computer-executable instructions for communicating a logical memory address pointer to the client indication, the logical memory address pointer indicating a current input position in the first virtual memory block.

10. The computer-readable medium of claim 8, wherein the computer-executable instructions further comprise instructions for:

receiving a request from the audio application to allocate the cyclical buffer for storage of audio data in a particular audio data format; and

.

responsive to receiving the request, performing operations of allocating the cyclical buffer.

11. The method of claim 8, wherein the method further comprises transferring data from consecutive logical addresses in the doubly mapped virtual memory into the cyclical buffer, the consecutive logical addresses sequentially corresponding to a last physical address of the cyclic buffer and a first physical address of the cyclic buffer.

12. A computing device comprising:

a processor; and

a memory coupled to the processor, the memory comprising computer-program instructions executable by the processor, the computer-program instructions including instructions for;

providing an interface for applications to input data into a cyclical buffer;

responsive to receiving a request via the interface from an application, returning a pointer to a logical address in virtual memory to the application, the virtual memory representing a double consecutive mapping of the cyclical buffer in the virtual memory;

the pointer allowing the application to write in a single data transfer directly into virtual memory using at least first and second logical addresses, a first logical address corresponding to an actual physical last address of the cyclical buffer, a second logical address corresponding to an actual physical first address of the cyclical buffer; and

wherein data written into the virtual memory is automatically transferred to the cyclical buffer for streaming and presentation to a user.

13. The computing device of claim 12, wherein an end portion of a first virtual mapping is page aligned with a beginning portion of a second virtual mapping, the first and second virtual mappings representing the double consecutive mapping of the cyclic buffer in the virtual memory.

14. The computing device of claim 12, wherein the application is an audio streaming application.

15. The computing device of claim 12, wherein the computer-program instructions further comprise instructions for:

receiving, via the interface, a request from the application to allocate the cyclical buffer; and

.

responsive to receiving the request, allocating the cyclic buffer via a device driver.

16. The computing device of claim 12, wherein the computer-program instructions further comprise a structure for transferring data from consecutive logical addresses in the double consecutive mapping into the cyclical buffer.