Vector Galois field multiply sum and accumulate instruction

• US 10,146,534 B2
• Filed: 10/06/2016
• Issued: 12/04/2018
• Est. Priority Date: 01/23/2013
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bradbury, Jonathan D.
• Primary Examiner(s): Coleman, Eric
• Application Number:
  US15/286,794
• Publication Number:
  US 20170024204A1
• Time in Patent Office: 789 Days
• Field of Search: None
• CPC Class Codes: G06F 9/3001 Arithmetic instructions
• CPC Class Codes: G06F 9/30018 Bit or string instructions
• CPC Class Codes: G06F 9/30029 Logical and Boolean instructions, e.g. XOR, NOT
• CPC Class Codes: G06F 9/30032 Movement instructions, e.g. MOVE, SHIFT, ROTATE, SHUFFLE
• CPC Class Codes: G06F 9/30036 Instructions to perform operations on packed data, e.g. vector, tile or matrix operations
• CPC Class Codes: G06F 9/30149 of variable length instructions
• CPC Class Codes: G06F 9/3016 Decoding the operand specifier, e.g. specifier format

Abstract

A Vector Galois Field Multiply Sum and Accumulate instruction. Each element of a second operand of the instruction is multiplied in a Galois field with the corresponding element of the third operand to provide one or more products. The one or more products are exclusively ORed with each other and exclusively ORed with a corresponding element of a fourth operand of the instruction. The results are placed in a selected operand.

Claims

1. A computer program product for executing a machine instruction in a central processing unit, the computer program product comprising:

a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

obtaining the machine instruction for execution, the machine instruction having associated therewith;

an opcode identifying a Vector Galois Field Multiply Sum and Accumulate operation;

a plurality of operands including a first operand, a second operand, a third operand, and a fourth operand; and

a control to specify a size of elements of the second operand and the third operand, wherein the control is specified by a mask associated with the machine instruction; and

executing the machine instruction, the executing comprising;

multiplying one or more elements of the second operand with one or more elements of the third operand using carryless multiplication to obtain a plurality of products;

performing a first mathematical operation on the plurality of products to obtain a first result;

performing a second mathematical operation on the first result and one or more selected elements of the fourth operand to obtain a second result; and

placing the second result in the first operand.

2. The computer program product of claim 1, wherein the multiplying comprises multiplying each element of the second operand with a corresponding element of the third operand using carryless multiplication resulting in even-odd pairs of double element-sized products.

3. The computer program product of claim 2, wherein the carryless multiplication has an order of two.

4. The computer program product of claim 2, wherein the first mathematical operation comprises an exclusive OR operation, and wherein the even-odd pairs of double element-sized products are exclusive ORed with each other to obtain the first result.

5. The computer program product of claim 4, wherein the second mathematical operation comprises an exclusive OR operation, and wherein the first result is exclusive ORed with a corresponding double-wide element of the fourth operand to obtain the second result.

6. The computer program product of claim 5, wherein the placing comprises placing the second result in a double-wide element of the first operand.

7. The computer program product of claim 1, wherein a size of the elements of the first operand and the fourth operand are double the size of the elements of the second operand and the third operand.

8. The computer program product of claim 1, wherein the machine instruction has associated therewith an extension field to be used in designating one or more registers, and wherein a first register field of the machine instruction is combined with a first portion of the extension field to designate a first register, the first register to be used to provide the first operand, a second register field is combined with a second portion of the extension field to designate a second register, the second register to be used to provide the second operand, a third register field is combined with a third portion of the extension field to designate a third register, the third register to be used to provide the third operand, and a fourth register field is combined with a fourth portion of the extension field to designate a fourth register, the fourth register to be used to provide the fourth operand.

9. A computer system for executing a machine instruction in a central processing unit, the computer system comprising:

a memory; and

a processor in communication with the memory, wherein the computer system is configured to perform a method, said method comprising;

obtaining the machine instruction for execution, the machine instruction having associated therewith;

an opcode identifying a Vector Galois Field Multiply Sum and Accumulate operation;

a plurality of operands including a first operand, a second operand, a third operand, and a fourth operand; and

a control to specify a size of elements of the second operand and the third operand, wherein the control is specified by a mask associated with the machine instruction; and

executing the machine instruction, the executing comprising;

multiplying one or more elements of the second operand with one or more elements of the third operand using carryless multiplication to obtain a plurality of products;

performing a first mathematical operation on the plurality of products to obtain a first result;

performing a second mathematical operation on the first result and one or more selected elements of the fourth operand to obtain a second result; and

placing the second result in the first operand.

10. The computer system of claim 9, wherein the multiplying comprises multiplying each element of the second operand with a corresponding element of the third operand using carryless multiplication resulting in even-odd pairs of double element-sized products.

11. The computer system of claim 10, wherein the carryless multiplication has an order of two.

12. The computer system of claim 10, wherein the first mathematical operation comprises an exclusive OR operation, and wherein the even-odd pairs of double element-sized products are exclusive ORed with each other to obtain the first result.

13. The computer system of claim 12, wherein the second mathematical operation comprises an exclusive OR operation, and wherein the first result is exclusive ORed with a corresponding double-wide element of the fourth operand to obtain the second result.

14. The computer system of claim 13, wherein the placing comprises placing the second result in a double-wide element of the first operand.

15. The computer system of claim 9, wherein a size of the elements of the first operand and the fourth operand are double the size of the elements of the second operand and the third operand.

16. The computer system of claim 9, wherein the machine instruction has associated therewith an extension field to be used in designating one or more registers, and wherein a first register field of the machine instruction is combined with a first portion of the extension field to designate a first register, the first register to be used to provide the first operand, a second register field is combined with a second portion of the extension field to designate a second register, the second register to be used to provide the second operand, a third register field is combined with a third portion of the extension field to designate a third register, the third register to be used to provide the third operand, and a fourth register field is combined with a fourth portion of the extension field to designate a fourth register, the fourth register to be used to provide the fourth operand.