A note on hash linking

ABSTRACT

In current machine designs, a machine address gives the user direct access to a single piece of information, namely the contents of that machine word. This note is based on the observation that it is often useful to associate additional information, with some (relatively few) address locations determined at run time, without the necessity of preallocating the storage at all possible such addresses. That is, it can be useful to have an effective extra bit, field, or address in some words without every word having to contain a bit (or bits) to mark this as a special case. The key idea is that this extra associated information can be found by a table search. Although it could be found by any search technique (e.g. linear, binary sorted, etc.), we suggest that an appropriate low overhead mechanism is to use hash search on a table in which the key is the address of the cell to be augmented.

REFERENCES

• 1: Daniel G. Bobrow , Daniel L. Murphy, Structure of a LISP system using two-level storage, Communications of the ACM, v.10 n.3, p.155-159, March 1967 [doi>10.1145/363162.363185]
• 2: Donald E. Knuth, The art of computer programming, volume 3: (2nd ed.) sorting and searching, Addison Wesley Longman Publishing Co., Inc., Redwood City, CA, 1998
• 3: Teitelman. W. Interlisp Reference Manual. Xerox Palo Alto Research Center, 1974.

INDEX TERMS

Primary Classification:
  E. Data
  E.2 DATA STORAGE REPRESENTATIONS
      Subjects: Hash-table representations

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
      D.2.5 Testing and Debugging
          Subjects: Monitors

  F. Theory of Computation
  F.2 ANALYSIS OF ALGORITHMS AND PROBLEM COMPLEXITY
      F.2.2 Nonnumerical Algorithms and Problems
          Subjects: Sorting and searching

General Terms:
Performance

Keywords:
address space extension, hash search, implicit pointers, monitor conditions