ISO/IEC INTERNATIONAL STANDARD 15200 First edition 1996-12-01 Information technology -- Adaptive Lossless Data Compression algorithm (ALDC) d'adaptation sans pertes (ALDC) IEC ISo Reference number ISO/IEC 15200:1996(E) Copyright Intermational Organization for Standardization rovided by IHS cense with1 rmitted without license from IHS Not for Resale ISO/IEC 15200:1996(E) Contents Foreword ii Introduction iv 1 Scope 1 2 Conformance 1 3 Normative Reference 1 4Definitions 1 4.1 Compressed Data Stream 1 4.2 Copy Pointer 1 4.3 Current Address 1 4.4Data Byte. 1 4.5Displacement Field. 4.6 End Marker 1 4.7 History Buffer. 1 4.8 Literal. 1 4.9 Matching String 1 4.10 Match Count 1 4.11 Match Count Field. 1 4.12 Pad Bits 1 5 Conventions and Notations 1 5.1 Representation of numbers 1 5.2 Names 2 6 ALDC compression algorithm 2 6.1 Encoding description for a 512-byte History Buffer 2 6.2 Description of the Compressed Data Stream 3 Annexes A - ALDC encoding format 5 B - ALDC Overview 7 C - ALDC Encoding Flow Chart 8 D - Bibliography 12 @ ISO/IEC1996 All rights reserved. Unless otherwise specified, no part of this publication may be repro- duced or utilized in any form or by any means, electronic or mechanical, including photo copying and microfilm, without permission in writing from the pubisher. ISO/IEC Copyright Office · Case postale 56 · CH-1211 Geneve 20 . Switzeriand Printed in Switzerland ermitted without license from IHS Not for Resale @ISO/IEC ISO/IEC 15200:1996 (E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75% of the national bodies casting a vote. International Standard ISO/IEC DIS 15200 was prepared by ECMA (as ECMA-222) and was adopted, under a special “fast- track procedure", by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by national bodies of ISO and IEC. AnnexesAtoDareforinformationonly Copyriahtlintemational Oorganizatinfor Standardization ii Nor rmitted without license from IHS Not for Resale