On-chip decompression engine

• US 7,861,073 B2
• Filed: 01/03/2007
• Issued: 12/28/2010
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wilson, Thomas James
• Primary Examiner(s): ELAMIN, ABDELMONIEM I
• Application Number:
  US11/650,183
• Publication Number:
  US 20080162920A1
• Time in Patent Office: 1,455 Days
• Field of Search: 713/1, 708/203, 710/68, 379/88.1, 348/14.13, 341/107
• US Class Current: 713/1
• CPC Class Codes: G06F 9/4401 Bootstrapping security arrangements therefor G06F21/57
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Abstract

Embodiments of the present invention are directed to a microcontroller which includes a Register Load Assist engine. The microcontroller can include no or minimal non-volatile memory which stores boot data. Thus, most of the boot data can be stored at a non-volatile memory external to the microcontroller. An external circuit can read the externally positioned non-volatile memory and send compressed boot data to the microcontroller. The boot data can be originally stored in compressed form in the external non-volatile memory or it can be compressed by the external circuit. The boot data can be received by the microcontroller and saved in an intermediate location in the microcontroller'"'"'s internal volatile memory. The RLA engine can then uncompress the boot data and store various portions of it in their final destinations (such as, for example, in respective registers).

Claims

1. A method for entering data into a register file of a processing module, the processing module including a processor and an application specific decompression engine distinct from the processor, the method comprising:

storing a first set of data into an intermediate memory, the first set of data comprising instructions and a set of compressed data including compressed initial register values to be stored in the register file of the processing module;

reading from the intermediate memory the compressed initial register values by the decompression engine;

retrieving a first set of one or more instructions from the first set of data by the decompression engine;

decompressing the compressed initial register values by the decompression engine to produce a set of decompressed initial values, wherein the decompressing is performed in accordance with the retrieved instructions;

transferring the decompressed initial values over an internal bus of the processing module to the register file of the processing module, and

saving in the register file the transferred decompressed initial values.

2. The method of claim 1, wherein the method is performed as part of a boot up procedure, and further including alerting the processor of the completion of a boot up procedure by the decompression engine.

3. The method of claim 1, further including receiving the first set of data from a source external to the processing module through a port of the processing module.

4. The method of claim 3, wherein the port of the processing module has a data transfer speed which is slower than a data transfer speed of the internal bus of the processing module.

5. The method of claim 1, wherein the processing module is a microcontroller.

6. The method of claim 1, wherein the decompression engine is an application specific circuit.

7. The method of claim 1, wherein decompressing the compressed initial register values further includes:

retrieving a reference to the set of compressed initial register values within the first set of data from the one or more instructions; and

accessing the set of compressed initial register values based on the reference.

8. The method of claim 1, wherein decompressing the set of compressed data further includes:

retrieving an indication of a method of decompression from the one or more instructions; and

decompressing the set of compressed initial register values according to the method of decompression.

9. The method of claim 8, further including:

retrieving a second set of one or more instructions;

retrieving a second indication of a second method of decompression from the second set of instructions, the second method of decompression being distinct from the method of decompression; and

decompressing a second set of compressed initial register values within the first set of data according to the second method of decompression.

10. The method of claim 1, wherein the register file comprises a plurality of registers and the size of each register in the register file is less than the processor word size.

11. The method of claim 1, wherein transferring the decompressed initial values over an internal bus comprises expanding the decompressed initial values into a bus word size optimized for transmission over the internal bus, and saving the transferred decompressed initial values includes reducing the bus word size into a word size optimized for storing in the register file.

12. The method of claim 1, wherein decompressing the compressed initial register values further comprises:

obtaining a value having a first number of significant bits from the compressed initial register values; and

appending a second number of insignificant bits to the value in order to form a resulting value of the processor'"'"'s word size.

13. The method of claim 1, wherein decompressing the set of compressed initial register values further comprises Huffman decoding the set of compressed initial register values.

14. The method of claim 1, wherein decompressing the set of compressed initial register values further comprises run length decoding the set of compressed initial register values.

15. The method of claim 1, further comprising:

receiving the first set of data by a communications interface of the processing module; and

activating the decompression engine by the communications interface;

wherein the storing of the first set of data is performed by the communications interface.

16. A method of loading initialization values into a microcontroller comprising a processor and a decompression engine, the method comprising:

receiving a set of data from a source external to the microcontroller by a communications interface of the microcontroller, the set of data including instructions and compressed initialization values, the compressed initialization values to be loaded into a register file of the microcontroller;

saving the set of data in a memory by the communications interface;

activating the decompression engine by the communications interface;

decompressing at least a portion of the set of data by the decompression engine in accordance with the instructions to obtain decompressed initialization values corresponding to the compressed initialization values;

transferring the decompressed initialization values over an internal bus of the microcontroller to a register file of the microcontroller, and

saving in the register file the transferred decompressed initialization values.

17. The method of claim 16 wherein the decompression engine comprises application specific circuits.

18. The method of claim 16, wherein the instruction includes a reference to a method of decompression, and the at least a portion of the set of data is decompressed according to the method of decompression.

19. The method of claim 16, wherein the register file comprises a plurality of registers and the size of each register in the register file is less than the processor word size.

20. The method of claim 16, further including notifying the processor of a completion of a boot up task by the decompression engine.

21. An electronic device comprising:

a processing module further including

a processor having an internal bus and a register file,

a memory connected to the processor over the internal bus, and

a decompression engine connected to the processor and the memory over the internal bus and comprising application specific electronics configured to

retrieve a set of data comprising a set of one or more instructions and compressed data including initialization values from the memory,

execute the one or more instructions in order to decompress the set of compressed data,

decompress the set of compressed data to obtain a set of uncompressed data,

transferring the uncompressed data over the internal bus of the processor to the register file of the processor, and

the register file operative to save the set of uncompressed data to registers within the register file; and

a compressed data source external to the processing module, the data source including the set of data and configured to send the set of data to the processing module.

22. The electronic device of claim 21, wherein the compressed data source further comprises a non-volatile memory, which comprises the set of data.

23. The electronic device of claim 21, wherein the register file comprises a plurality of registers and the size of each register in the register file is less than the processor word size.

24. The electronic device of claim 21, wherein the one or more instructions further comprise a reference to a decompression method, and the decompression engine is further configured to use the decompression method to decompress the set of compressed data.

25. The electronic device of claim 21, wherein the processing module is a microcontroller.

26. The electronic device of claim 21, wherein the processing module further comprises:

a communications port connected to the compressed data source; and

wherein the internal bus features a data transfer rate which is faster than that of the communications port.

27. The electronic device of claim 26, wherein the communications port is a serial port, and the internal bus is a parallel bus.

28. The electronic device of claim 26, wherein the processing module further comprises a communications interface comprising digital logic configured to cause the communications interface to:

receive the set of data from the compressed data source;

save the set of data into the memory; and

activate the decompression engine.

29. The electronic device of claim 21, wherein the initialization values are required for a boot up procedure.

30. The electronic device of claim 21, wherein the electronic device is a mobile telephone.

31. The electronic device of claim 21, wherein the electronic device is a portable audio player.

32. An electronic device comprising:

a processing module further comprising

a processor having an internal bus and a register file,

means for storing data in a memory connected to the processor,

retrieval means for retrieving from the memory a set of data comprising one or more instructions and a set of compressed data, wherein the compressed data includes initialization values to be stored in the register file of the processor,

decompression means for executing the one or more instructions to decompress the set of compressed data to obtain a set of uncompressed data,

means for transferring the decompressed data over the internal bus to the register file, and

storage means for storing the set of uncompressed data in registers of the register file; and

external data source means for sending the set of data to the processing module, the external data source means being external to the processing module.

33. A micro controller comprising:

a processor;

a register file;

a receiving means for receiving a set of data from a source external to the microcontroller, the set of data including one or more instructions and compressed data including compressed initialization values;

a storage means for storing the set of data in a memory;

a decompression means for decompressing the compressed data in accordance with the one or more instructions to obtain a set of decompressed data including decompressed initialization values, the decompression means further transmitting the decompressed initialization values the register file; and

a decompressed data storage means for storing the set of decompressed data into a destination memory;

wherein the decompression means are distinct from the processor.

34. A mobile telephone comprising:

a processing module further comprising

a processor having an internal bus and a register file,

a memory connected to the processor over the internal bus, and

a decompression engine connected to the processor and the memory over the internal bus and comprising application specific electronics configured to

retrieve a set of data comprising a set of one or more instructions and compressed data including initialization values from the memory,

execute the one or more instructions in order to decompress the set of compressed data,

decompress the set of compressed data to obtain a set of uncompressed data,

transferring the uncompressed data over the internal bus of the processor to the register file of the processor, and

save the set of uncompressed data to registers within the register file; and

a compressed data source external to the processing module, comprising the set of data and configured to send the set of data to the processing module.

35. A digital audio player comprising:

a processing module further comprising

a processor having an internal bus and a register file,

a memory connected to the processor over the internal bus, and

a decompression engine connected to the processor and the memory over the internal bus and comprising application specific electronics configured to

retrieve a set of data comprising a set of one or more instructions and compressed data including initialization values from the memory,

execute the one or more instructions in order to decompress the set of compressed data,

decompress the set of compressed data to obtain a set of uncompressed data,

transferring the uncompressed data over the internal bus of the processor to the register file of the processor, and

save the set of uncompressed data to registers within the register file; and

a compressed data source external to the processing module, comprising the set of data and configured to send the set of data to the processing module.

36. A method for entering data into a register file of a processing module, the processing module including a processor and a decompression engine, the method comprising:

storing in an intermediate memory, compressed initial register values to be stored in the register file of the processing module;

reading from the intermediate memory the compressed initial register values by the decompression engine;

decompressing the compressed initial register values by the decompression engine to produce a set of decompressed initial values;

transferring the decompressed initial values to the register file of the processing module, and

saving in the register file the transferred decompressed initial values.

37. The method as recited in claim 36 further comprising:

configuring the register file to have a word length smaller than a word length of the intermediate memory.

38. The method as recited in claim 36

wherein transferring the decompressed initial values comprises:

transferring the decompressed initial values over an internal bus of the processing module and

expanding the decompressed initial values into a bus word size optimized for transmission over the internal bus, and

wherein saving the transferred decompressed initial values includes;

reducing the bus word size into a word size optimized for storing in the register file.

39. The method as recited in claim 37

wherein transferring the decompressed initial values comprises:

transferring the decompressed initial values over an internal bus of the processing module and

expanding the decompressed initial values into a bus word size optimized for transmission over the internal bus, and

wherein saving the transferred decompressed initial values includes;

reducing the bus word size into a word size optimized for storing in the register file.

40. An electronic device comprising:

a processing module further including

a processor having an internal bus and a register file,

a memory connected to the processor over the internal bus, and

a decompression engine connected to the processor and the memory over the internal bus and configured to

retrieve compressed initialization values from the memory,

decompress the compressed initialization values to obtain a set of uncompressed initialization values,

transfer the uncompressed initialization to the register file of the processor, and

save the set of uncompressed initialization values to registers within the register file.

41. The electronic device as recited in claim 40 wherein the transfer of the uncompressed initialization values includes transferring the uncompressed initialization values over an internal bus of the processor and expanding the uncompressed initialization values into a bus word size optimized for transmission over the internal bus, and the saving of the set of uncompressed initialization values includes reducing the bus word size into a word size optimized for storing in the register file.

42. The electronic device as recited in claim 41 wherein the register file word length is smaller than the word length of the memory.

43. The electronic device as recited in claim 40 wherein the register file word length is smaller than the word length of the memory.

44. The electronic device as recited in claim 40 further comprising:

a compressed data source external to the processing module, the compressed data source including the initialization values and configured to send the initialization values to the processing module.

45. The electronic device as recited in claim 40 wherein the electronic device comprises a micro controller, a mobile telephone, or a digital audio player.