Merging With Offset Value Codes and the Vector Facility
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
This invention describes an algorithm which uses "offset value codes" to merge sorted strings together effectively with the IBM 3090 Vector Facility. An offset value code is a way of coding the relationship between two keys, and presents a faster replacement-selection algorithm based on this code. The offset value code is formed by comparing two keys a halfword at a time. When two halfwords being compared are unequal, a "codeword" is formed by taking the offset and the value of the unequal halfword. Specifically, the offset value code is a 4-byte codeword consisting of two parts: the first two bytes specify the byte offset of the halfword just beyond the first unequal halfword; and the next two bytes contain the one's complement of the first unequal halfword.