Data processor with CRC instruction set extension

• US 6,192,491 B1
• Filed: 11/09/1998
• Issued: 02/20/2001
• Est. Priority Date: 06/15/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bahr, Raymond G., Cashman, John D., Ye, Wei, Riley, Paul M.
• Primary Examiner(s): Follansbee, John A.
• Application Number:
  US09/189,016
• Time in Patent Office: 834 Days
• Field of Search: 709/230, 709/236, 709/237, 709/246, 709/247, 714/18, 714/21, 714/48, 714/49, 714/50-52, 712/227
• US Class Current: 714/52
• CPC Class Codes: G06F 9/3004 to perform operations on memory
• CPC Class Codes: G06F 9/30072 to perform conditional operations, e.g. using predicates or guards
• CPC Class Codes: G06F 9/30087 Synchronisation or serialisation instructions
• CPC Class Codes: H04L 69/12 Protocol engines
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A programmable data communications device is provided to process multiple streams of data according to multiple protocols. The device is equipped with a co-processor including multiple, programmable processors allowing data to be operated on by multiple protocols. The programmable processors within the co-processor include extended instruction sets including instructions providing the operations of zero stuffing, CRC computation, partial compare, conditional move, and trie traversal. These instructions allow the processor(s) of the co-processor to more efficiently execute programs implementing data communications protocols. Since each processor is programmable, protocols standards which change may be accommodated. A network device equipped with the co-processor can handle multiple simultaneous streams of data and can implement multiple protocols on each data stream. The protocols can execute within the co-processor either independently of each other, or in conjunction with each other.

Claims

1. A processor comprising:

a first input receiving a first input data, a second input receiving a second input data, a third input receiving a third input data and a fourth input receiving a CRC instruction;

a logic unit coupled to the first input, the second input, the third input and the fourth input, the logic unit including activatible CRC circuitry which is activated upon receipt of the CRC instruction and which performs a calculation of a CRC value based upon;

I) the polynomial defined in the first input data;

ii) the current state of the CRC calculation stored in the second input data; and

iii) a third input data containing a portion of a message upon which to calculate a CRC;

an output coupled to the logic unit, the output outputting the CRC value in a predefined location; and

wherein the processor can be programmed to process one of many different instructions, including at least one instruction from a group comprising;

a zero stuffing instruction, a zero unstuffing instruction, a partial subtraction and conditional move instruction, a partial compare and conditional move instruction and a multiple compare instruction.

2. The processor of claim 1 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform compression on the data.

3. The processor of claim 1 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform decompression on the data.

4. The processor of claim 1 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform encryption on the data.

5. The processor of claim 1 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform decryption on the data.

6. An apparatus comprising a computer readable medium having a CRC instruction recorded thereon, the apparatus comprising:

a first input receiving a first input data, a second input receiving a second input data, a third input receiving a third input data and a fourth input receiving a CRC instruction;

a logic unit coupled to the first input, the second input, the third input and the fourth input, the logic unit including activatible CRC circuitry which is activated upon receipt of the CRC instruction and which performs a calculation of a CRC value based upon;

I) the polynomial defined in the first input data;

ii) the current state of the CRC calculation stored in the second input data; and

iii) a third input data containing a portion of a message upon which to calculate a CRC;

an output coupled to the logic unit, the output outputting the CRC value in a predefined location; and

wherein the processor can be programmed to process one of many different instructions, including at least one instruction from a group comprising;

a zero stuffing instruction, a zero unstuffing instruction, a partial subtraction and conditional move instruction, a partial compare and conditional move instruction and a multiple compare instruction.

7. A method of processing data in a processor comprising the steps of:

coupling a first input data, a second input data, a third input data and a CRC instruction to a logic unit;

activating CRC circuitry in the logic unit upon receipt of the CRC instruction;

calculating a CRC value based upon;

I) the polynomial defined in the first input data;

ii) the current state of the CRC instruction stored in the second input data; and

iii) the third input data containing a portion of a message upon which to calculate a CRC;

outputting the CRC value to a predefined location; and

programming the processor to process one of many different instructions, including at least one instruction from a group comprising;

a zero stuffing instruction, a zero unstuffing instruction, a partial subtraction and conditional move instruction, a partial compare and conditional move instruction and a multiple compare instruction.

8. The method of claim 7 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform compression on the data.

9. The method of claim 7 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform decompression on the data.

10. The method of claim 7 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform encryption on the data.

11. The method of claim 7 wherein the CRC instruction executes on the logic unit as part of the communications software protocol to perform decryption on the data.