Method for performing multiply-substrate operations on packed data

A method for manipulating a first packed data and a second packed data, said first packed data including A.sub.1, A.sub.2, A.sub.3, and A.sub.4 as data elements, said second packed data including B.sub.1, B.sub.2, B.sub.3, and B.sub.4 as data elements, said method comprising the computer-implemented steps of:

• performing the following steps in response to executing a single multiply-subtract instruction,
• performing the operation (A.sub.1 .times.B.sub.1)-(A.sub.2 .times.B.sub.2) to generate a first data element in a third packed data;
• performing the operation (A.sub.3 .times.B.sub.3)-(A.sub.4 .times.B.sub.4) to generate a second data element in said third packed data;
• storing said third packed data in a first storage area.

In a computer system having stored therein a first packed data and a second packed data each containing initial data elements, each of said initial data elements in said first packed data having a corresponding initial data element in said second packed data, a method for performing multiply subtract operations, said method comprising the steps of:

• performing the following steps in response to executing a single instruction,
• multiplying together said corresponding initial data elements in said first packed data and said second packed data to generate corresponding intermediate data elements, said intermediate data elements being divided into a number of sets;
• subtracting the intermediate result data elements in at least a first of said number of sets;
• storing the result of subtracting the first of said number of sets as a first of a plurality of result data elements;
• and
• storing said result data elements as a third packed data in a memory.