1、 Reference numberISO/IEC 22091:2002(E)ISO/IEC 2002Information technology Streaming Lossless Data Compression algorithm (SLDC) Technologies de linformation Algorithme de compression sans perte de donnes en mode continu (SDLC) National Standard of CanadaCAN/CSA-ISO/IEC 22091:04(ISO/IEC 22091:2002)Inte
2、rnational Standard ISO/IEC 22091:2002 (first edition, 2002-09-15) has been adopted without modification(IDT) as CSA Standard CAN/CSA-ISO/IEC 22091:04, which has been approved as a National Standard of Canadaby the Standards Council of Canada.ISBN 1-55397-267-8 January 2004The Canadian Standards Asso
3、ciation (CSA), The Standards Council of Canada is theunder whose auspices this National Standard has been coordinating body of the National Standards system, produced, was chartered in 1919 and accredited by a federation of independent, autonomousthe Standards Council of Canada to the National organ
4、izations working towards the furtherStandards system in 1973. It is a not-for-profit, development and improvement of voluntarynonstatutory, voluntary membership association standardization in the national interest.engaged in standards development and certification The principal objects of the Counci
5、l are to foster activities. and promote voluntary standardization as a means CSA standards reflect a national consensus of of advancing the national economy, benefiting theproducers and users including manufacturers, health, safety, and welfare of the public, assisting consumers, retailers, unions a
6、nd professional and protecting the consumer, facilitating domestic organizations, and governmental agencies. The and international trade, and furthering internationalstandards are used widely by industry and commerce cooperation in the field of standards.and often adopted by municipal, provincial, a
7、nd A National Standard of Canada is a standard whichfederal governments in their regulations, particularly in has been approved by the Standards Council ofthe fields of health, safety, building and construction, Canada and one which reflects a reasonableand the environment. agreement among the views
8、 of a number of capableIndividuals, companies, and associations across individuals whose collective interests provide to theCanada indicate their support for CSAs standards greatest practicable extent a balance ofdevelopment by volunteering their time and skills to representation of producers, users
9、, consumers, andCSA Committee work and supporting the Associations others with relevant interests, as may be appropriateobjectives through sustaining memberships. The more to the subject in hand. It normally is a standardthan 7000 committee volunteers and the 2000 which is capable of making a signif
10、icant and timelysustaining memberships together form CSAs total contribution to the national interest.membership from which its Directors are chosen. Approval of a standard as a National Standard ofSustaining memberships represent a major source of Canada indicates that a standard conforms to theinc
11、ome for CSAs standards development activities. criteria and procedures established by the StandardsThe Association offers certification and testing Council of Canada. Approval does not refer to theservices in support of and as an extension to its technical content of the standard; this remains thest
12、andards development activities. To ensure the continuing responsibility of the accreditedintegrity of its certification process, the Association standards-development organization.regularly and continually audits and inspects products Those who have a need to apply standards arethat bear the CSA Mar
13、k. encouraged to use National Standards of CanadaIn addition to its head office and laboratory complex whenever practicable. These standards are subject in Toronto, CSA has regional branch offices in major to periodic review; therefore, users are cautioned centres across Canada and inspection and te
14、sting to obtain the latest edition from the organizationagencies in eight countries. Since 1919, the preparing the standard.Association has developed the necessary expertise to The responsibility for approving National Standards meet its corporate mission: CSA is an independent of Canada rests with
15、theservice organization whose mission is to provide an Standards Council of Canadaopen and effective forum for activities facilitating the 270 Albert Street, Suite 200exchange of goods and services through the use of Ottawa, Ontario, K1P 6N7standards, certification and related services to meet Canad
16、anational and international needs.For further information on CSA services, write toCanadian Standards Association5060 Spectrum Way, Suite 100Mississauga, Ontario, L4W 5N6CanadaAlthough the intended primary application of this Standard is stated in its Scope, it is importantto note that it remains th
17、e responsibility of the users to judge its suitability for their particular purpose.Registered trade-mark of Canadian Standards AssociationCAN/CSA-ISO/IEC 22091:04 Information technology Streaming Lossless Data Compression algorithm (SLDC)January 2004 Canadian Standards Association CSA/1CAN/CSA-ISO/
18、IEC 22091:04Information technology Streaming Lossless DataCompression algorithm (SLDC)CSA PrefaceStandards development within the Information Technology sector is harmonized with internationalstandards development. Through the CSA Technical Committee on Information Technology (TCIT),Canadians serve
19、as the Canadian Advisory Committee (CAC) on ISO/IEC Joint Technical Committee 1 onInformation Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO memberbody for Canada and sponsor of the Canadian National Committee of the IEC. Also, as a member of theInternational Telecommun
20、ication Union (ITU), Canada participates in the International Telegraph andTelephone Consultative Committee (ITU-T).This International Standard was reviewed by the CSA TCIT under the jurisdiction of the StrategicSteering Committee on Information Technology and deemed acceptable for use in Canada. (A
21、committee membership list is available on request from the CSA Project Manager.) From time to time,ISO/IEC may publish addenda, corrigenda, etc. The CSA TCIT will review these documents for approvaland publication. For a listing, refer to the CSA Information Products catalogue or CSA Info Update orc
22、ontact a CSA Sales representative. This Standard has been formally approved, without modification, bythe Technical Committee and has been approved as a National Standard of Canada by the StandardsCouncil of Canada.January 2004 Canadian Standards Association 2004All rights reserved. No part of this p
23、ublication may be reproduced in any form whatsoever without the prior permission ofthe publisher. ISO/IEC material is reprinted with permission. Where the words “this International Standard” appear in thetext, they should be interpreted as “this National Standard of Canada”. Inquiries regarding this
24、 National Standard of Canada should be addressed to Canadian Standards Association 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6 1-800-463-6727 416-747-4044www.csa.caReference numberISO/IEC 22091:2002(E)ISO/IEC 2002INTERNATIONAL STANDARD ISO/IEC22091First edition2002-09-15Inform
25、ation technology Streaming Lossless Data Compression algorithm (SLDC) Technologies de linformation Algorithme de compression sans perte de donnes en mode continu (SDLC) ISO/IEC 22091:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this
26、 file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretar
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28、 that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO/IEC 2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or util
29、ized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax
30、+ 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch ii ISO/IEC 2002 All rights reservedISO/IEC 22091:2002(E) ISO/IEC 2002 All rights reserved iiiContents 1 Scope 1 2 Conformance 1 3 Normative reference 1 4 Terms and definitions 1 4.1 Access Point 1 4.2 Control Symbol 1 4.3 Copy Pointer 1 4.4 dat
31、a byte 1 4.5 Data Symbol 1 4.6 Displacement Field 1 4.7 Encoded Data Stream 1 4.8 Encoded Record 1 4.9 End Marker 2 4.10 End Of Record Symbol (EOR Symbol) 2 4.11 File Mark 2 4.12 File Mark Symbol 2 4.13 Flush Symbol 2 4.14 History Buffer 2 4.15 Literal 1 2 4.16 Literal 2 2 4.17 Matching String 2 4.1
32、8 Match Count 2 4.19 Match Count Field 2 4.20 Pad 2 4.21 Record 2 4.22 Record Segment 2 4.23 Reset X Symbol 2 4.24 Reset 1 Symbol 2 4.25 Reset 2 Symbol 2 4.26 scheme 1 2 4.27 Scheme 1 Symbol 2 4.28 scheme 2 3 4.29 Scheme 2 Symbol 3 4.30 user data 3 5 Conventions and Notations 3 5.1 Representation of
33、 numbers 3 5.2 Names 3 6 Acronyms 3 7 Algorithm Overview 3 7.1 Scheme 1 Encoding 3 7.2 Scheme 2 Encoding 3 7.3 History Buffer 4 8 Encoding Specification 4 8.1 User Data 4 8.2 History Buffer 4 8.3 Encoded Data Stream 4 ISO/IEC 22091:2002(E) iv ISO/IEC 2002 All rights reserved8.3.1 Access Point 5 8.4
34、Data Symbols 5 8.4.1 Literal 1 Data Symbols 5 8.4.2 Copy Pointer Data Symbols 5 8.4.3 Literal 2 Data Symbols 6 8.5 Control Symbols 7 8.6 Pad 8 ISO/IEC 22091:2002(E) ISO/IEC 2002 All rights reserved vForeword ISO (the International Organization for Standardization) and IEC (the International Electrot
35、echnical 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
36、 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
37、committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by the joint technical committee are circula
38、ted to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO and IEC shall
39、not be held responsible for identifying any or all such patent rights. ISO/IEC 22091 was prepared by ECMA (as ECMA-321) 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
40、 and IEC. INTERNATIONAL STANDARD ISO/IEC 22091:2002(E) ISO/IEC 2002 All rights reserved 1Information technology Streaming Lossless Data Compression algorithm (SLDC) 1 Scope This International Standard specifies a lossless compression algorithm to reduce the number of 8-bit bytes required to represen
41、t data records and File Marks. The algorithm is known as Streaming Lossless Data Compression algorithm (SLDC). One buffer size (1 024 bytes) is specified. The numerical identifier according to ISO/IEC 11576 allocated to this algorithm is 6. 2 Conformance A compression algorithm shall be in conforman
42、ce with this International Standard if its Encoded Data Stream satisfies the requirements of this International Standard. 3 Normative reference The following normative document contains provisions which, through reference in this text, constitute provisions of this International Standard. For dated
43、references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative document indicated below. For undated
44、 references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO/IEC 11576:1994 Information technology Procedure for the registration of algorithms for the lossless compression of data 4 Terms and
45、 definitions For the purpose of this International Standard the following terms and definitions apply. 4.1 Access Point A location in the Encoded Data Stream at which data may be decoded. 4.2 Control Symbol A Control Symbol may change the compression scheme, reset the History Buffer, mark the end of
46、 a Record, indicate a File Mark, or indicate the termination of an Encoded Data Stream. 4.3 Copy Pointer A part of the Encoded Data Stream output in scheme 1 that replaces a string of data bytes with a specification of a Matching String. 4.4 data byte An element of user data that is to be encoded. 4
47、.5 Data Symbol An element of an Encoded Record that represents one or more data bytes. 4.6 Displacement Field A field in the Copy Pointer that specifies the location within the History Buffer of the first byte of a Matching String. 4.7 Encoded Data Stream The output stream after encoding User Data.
48、4.8 Encoded Record The output stream after encoding one Record of user data. ISO/IEC 22091:2002(E) 2 ISO/IEC 2002 All rights reserved4.9 End Marker A Control Symbol that denotes termination of an Encoded Data Stream. 4.10 End Of Record Symbol (EOR Symbol) A Control Symbol that denotes the end of a R
49、ecord in the Encoded Data Stream. 4.11 File Mark A recorded element used to mark organisational boundaries (e.g. directory boundaries) in user data. 4.12 File Mark Symbol A Control Symbol in Encoded Data Stream that denotes a File Mark in user data. 4.13 Flush Symbol A Control Symbol that, if required, is followed by Pad to make the size of the Encoded Data Stream an integer multiple of 32 bits. 4.14 History Buffer A data structure where incoming data bytes are stored for use by scheme 1 compression and decompression. 4.15 L
