PAL CARD CATALOG ENTRY

SHORT DESCRIPTION

Components for compressing object code


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ASSET PROFILE

UNIT NAME
OCC
VERSION
1.1
REVIEW CODE
C1 1.0 A
INET ADDRESS
librarian@source.asset.com
AUTHOR
Bruce A. Petrick
The Aerospace Corporation
RIGHTS
Approved for public release; distribution unlimited
COPYRIGHT
1993 The Aerospace Corporation
DATE CREATED
15 March 1993
DATE RELEASED
11 December 1993
DATE LAST UPDATED
11 December 1993
LOCATION
ASSET
PAL
ENVIRONMENT
Not documented in PAL database
LIMITATIONS
Not documented in PAL database
CERTIFICATION
Ada System Certifier_1 1.0
Date/Time of Processing: Monday    30 May       1994 01:42:05Pm
Overall Assessment of System: OK
Classification of System: A
Basis of Classification --
Syntax Errors                               PASS
Completeness                                PASS
Independence from External Libraries        PASS
Independence from a Specific Ada Compiler   PASS

Number of ...
Files              22
Library Units      22
Lines            3437
Statements       1167
Comments          266

FILE LISTING

Directory Display


languages/ada/swcomps/occ:
  File Name                 Size
  ---------                 ----
  README                     909
  occ.zip                 35,425


Totals
  ==============  ==============
    2 Files               36,334

ABSTRACT

ASSET_A_467:  Object Code Compression Algorithm
     The main procedures in this compilation closure demonstrate the
ability to  compress streams of byte (or word) data without loss of
bits.  The main  attribute of this scheme is that the decompression
phase is very fast, and does not require any additional buffer space or
table space.  This makes it well  suited for certain situations such as
compressing code in ROM for decompression  into RAM before execution,
where the ROM is a limited resource.
     The compression/decompression algorithm is based on the replacement
of  matching patterns within the stream with special marker tokens that
reference a  prior occurrence of the pattern.
     This capability was originally developed to demonstrate the
feasibility of  compressing MIL-STD-1750A object code in ROM within a
space-borne computer.   Compression ratios from 1.3 to 2.0 have been
achieved.


REVISION HISTORY

15 March 1993      Bruce A Petrick   Initial release to ASSET
11 December 1993   ASSET             Initial release to the PAL


RELEASE NOTICE

This prologue must be included in all copies of this software.
Restrictions on use or distribution:  NONE


DISCLAIMER

	This software and its documentation are provided "AS IS" and
without any expressed or implied warranties whatsoever.  No warranties
as to performance, merchantability, or fitness for a particular
purpose exist.
	The user is advised to test the software thoroughly before
relying on it.  The user must assume the entire risk and liability of
using this software.  In no event shall any person or organization of
people be held responsible for any direct, indirect, consequential or
inconsequential damages or lost profits.