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Optimizing Element Lists

IP.com Disclosure Number: IPCOM000077947D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Poland, TA: AUTHOR

Abstract

This method of describing element lists allows additional elements to be inserted into lists, without affecting the storage allocated to each list. The method optimizes the number of keys which can be sorted internally within a fixed-storage structure. Instead of using registers and counters to control key comparisons, direct addresses and variable instruction mask fields are used.

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Optimizing Element Lists

This method of describing element lists allows additional elements to be inserted into lists, without affecting the storage allocated to each list. The method optimizes the number of keys which can be sorted internally within a fixed-storage structure. Instead of using registers and counters to control key comparisons, direct addresses and variable instruction mask fields are used.

The element lists and flag bytes, in Figs. 1 and 2, respectively, are at fixed locations, but the keys or indicators contained within them are at variable locations. By compiling or building variable lengths and indicator masks into a compare loop, the internal sort is adapted to handle the most keys possible for a particular key length. The compiling is done by an interactive phase which tailors the sort phase according to user record definitions. This fine tuning is transparent to the sort Phase.

The internal sort compare loop must handle two exceptional conditions. First, any key in the list as indicated by the numbers in Fig. 1 may be out-of-sequence relative to the current output string being generated for the merge phase. Second, the end of the keys in the list must be detected.

Both conditions are identified in the flag byte associated with an element list. In Fig. 2, the numbers within the flag bytes are on/off indicators, signaling the status of their associated keys as being in-sequence or out-of-sequence for the current string. The E-bit signals the...