1、 IEC 61691-1-1 Edition 2.0 2011-0g24 INTERNATIONAL STANDARD Behavioural languages Part 1-1: VHDL Language Reference Manual IEC 61691-1-1:2011(E)IEEE Std1076-2008IEEE Std 1076THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2008 IEEE All rights reserved. IEEE is a registered trademark in the U.S. Pa
2、tent any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for S
3、tandardization (ISO) in accordance with conditions determined by agreement between the two organizations.2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has
4、 representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurat
5、e, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user.4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional p
6、ublications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some a
7、reas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies.6) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for ident
8、ifying any or all such patent rights.International Standard IEC 61691-1-1/IEEE Std 1076 has been processed through IEC technical committee 93: Design automation.This second edition cancels and replaces the first edition published in 2004. This edition constitutes a technical revision.The text of thi
9、s standard is based on the following documents:g3Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table.IEEE Std FDIS Report on voting1076 (2008) 93/302/FDIS 93/304/RVDIEC 61691-1-1:2011(E) - viii - g3IEEE Std 1076-2008Publi
10、shed by IEC under license from IEEE. 2008 IEEE. All rights reserved.A list of parts of the IEC 61691 series can be found on the IEC website.The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/websto
11、re.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended.- ix - IEC 61691-1-1:2011(E)g3IEEE Std 1076-2008Published by IEC under license from IEEE. 2008 IEEE. All rights reserved.IEC/IEEE Dual L
12、ogo International StandardsThis Dual Logo International Standard is the result of an agreement between the IEC and the Institute of Electrical and Electronics Engineers, Inc. (IEEE). The original IEEE Standard was submitted to the IEC for consideration under the agreement, and the resulting IEC/IEEE
13、 Dual Logo International Standard has been published in accordance with the ISO/IEC Directives.IEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating Committees of the IEEE Standards Association (IEEE-SA) Standards Board. The IEEE develops its standards throu
14、gh a consensus development process, approved by the American National Standards Institute, which brings together volunteers representing varied viewpoints and interests to achieve the final product. Volunteers are not necessarily members of the Institute and serve without compensation. While the IEE
15、E administers the process and establishes rules to promote fairness in the consensus development process, the IEEE does not independently evaluate, test, or verify the accuracy of any of the information contained in its standards.Use of an IEC/IEEE Dual Logo International Standard is wholly voluntar
16、y. The IEC and IEEE disclaim liability for any personal injury, property or other damage, of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance upon this, or any other IEC or IEEE Standard docum
17、ent. The IEC and IEEE do not warrant or represent the accuracy or content of the material contained herein, and expressly disclaim any express or implied warranty, including any implied warranty of merchantability or fitness for a specific purpose, or that the use of the material contained herein is
18、 free from patent infringement. IEC/IEEE Dual Logo International Standards documents are supplied “AS IS”. The existence of an IEC/IEEE Dual Logo International Standard does not imply that there are no other ways to produce, test, measure, purchase, market, or provide other goods and services relate
19、d to the scope of the IEC/IEEE Dual Logo International Standard. Furthermore, the viewpoint expressed at the time a standard is approved and issued is subject to change brought about through developments in the state of the art and comments received from users of the standard. Every IEEE Standard is
20、 subjected to review at least every five years for revision or reaffirmation. When a document is more than five years old and has not been reaffirmed, it is reasonable to conclude that its contents, although still of some value, do not wholly reflect the present state of the art. Users are cautioned
21、 to check to determine that they have the latest edition of any IEEE Standard.In publishing and making this document available, the IEC and IEEE are not suggesting or rendering professional or other services for, or on behalf of, any person or entity. Neither the IEC nor IEEE is undertaking to perfo
22、rm any duty owed by any other person or entity to another. Any person utilizing this, and any other IEC/IEEE Dual Logo International Standards or IEEE Standards document, should rely upon the advice of a competent professional in determining the exercise of reasonable care in any given circumstances
23、.Interpretations Occasionally questions may arise regarding the meaning of portions of standards as they relate to specific applications. When the need for interpretations is brought to the attention of IEEE, the Institute will initiate action to prepare appropriate responses. Since IEEE Standards r
24、epresent a consensus of concerned interests, it is important to ensure that any interpretation has also received the concurrence of a balance of interests. For this reason, IEEE and the members of its societies and Standards Coordinating Committees are not able to provide an instant response to inte
25、rpretation requests except in those cases where the matter has previously received formal consideration.Comments for revision of IEC/IEEE Dual Logo International Standards are welcome from any interested party, regardless of membership affiliation with the IEC or IEEE. Suggestions for changes in doc
26、uments should be in the form of a proposed change of text, together with appropriate supporting comments. Comments on standards and requests for interpretations should be addressed to:Secretary, IEEE-SA Standards Board, 445 Hoes Lane, Piscataway, NJ 08854, USA and/or General Secretary, IEC, 3, rue d
27、e Varemb, PO Box 131, 1211 Geneva 20, Switzerland. Authorization to photocopy portions of any individual standard for internal or personal use is granted by the Institute of Electrical and Electronics Engineers, Inc., provided that the appropriate fee is paid to Copyright Clearance Center. To arrang
28、e for payment of licensing fee, please contact Copyright Clearance Center, Customer Service, 222 Rosewood Drive, Danvers, MA 01923 USA; +1 978 750 8400. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Cent
29、er.NOTE Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE shall
30、 not be responsible for identifying patents for which a license may be required by an IEEE standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention.IEC 61691-1-1:2011(E) - x - g3IEEE Std 1076-2008Published by IEC under license from IEEE
31、. 2008 IEEE. All rights reserved.- xi - IEC 61691-1-1:2011(E)g3IEEE Std 1076-2008Published by IEC under license from IEEE. 2008 IEEE. All rights reserved.g3IEEE Standard VHDL Language Reference ManualSponsor Design Automation Standards Committeeg3of theg3IEEE Computer SocietyApproved 26 September 20
32、08g3IEEE SA-Standards BoardIEEE and POSIX are registered trademarks in the U.S. Patent the communication of hardware design data; and the maintenance, modification, and procurement of hardware. Its primary audiences are the implementors of tools supporting the language and the advanced users of the
33、language.Keywords: computer languages, electronic systems, hardware, hardware design, VHDL- xiii - IEC 61691-1-1:2011(E)g3IEEE Std 1076-2008Published by IEC under license from IEEE. 2008 IEEE. All rights reserved.IEEE introductiong3The VHSIC Hardware Description Language (VHDL) is a formal notation
34、intended for use in all phases of the creation of electronic systems. Because it is both machine readable and human readable, it supports the development, verification, synthesis, and testing of hardware designs; the communication of hardware design data; and the maintenance, modification, and procu
35、rement of hardware.This document, IEEE Std 1076-2008, is a revision of IEEE Std 1076-2002 as amended by IEEE Std 1076cTM-2007. Initial work on gathering requirements and developing language extensions was undertaken by the IEEE VHDL Analysis and Standardization Group (VASG), otherwise known as the 1
36、076 Working Group. Subsequently, Accelleraasponsored an effort to complete that work and draft a revised Language Reference Manual. That draft was returned to IEEE for final revision and approval, resulting in this document and the associated machine-readable files. This revision incorporates numero
37、us enhancements, both major and minor, to previously existing language feaures and several new language features. The changes are summarized in Annex E. In addition, several VHDL library packages that were previously defined in separate standards are now defined in this standard, ensuring that they
38、are treated as integral parts of the language. Finally, this revision incorporates the IEEE Property Specification Language (PSL) as part of VHDL. The combination of these changes significantly improves VHDL as a language for specification, design, and verification of complex electronic systems.The
39、maintenance of the VHDL language standard is an ongoing process. The chair of the VHDL Analysis and Standardization Group extends his gratitude to all who have participated in this revision, both in the IEEE committees and the Accellera effort, and encourages the participation of all interested part
40、ies in future language revisions.bNotice to usersLaws and regulationsUsers of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of the standard are resp
41、onsible for observing or referring to the applicable regulatory requirements. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so. CopyrightsThis document is copyrighted by the
42、IEEE. It is made available for a wide variety of both public and private uses. These include both use, by reference, in laws and regulations, and use in private self-regulation, standardization, and the promotion of engineering practices and methods. By making this document available for use and ado
43、ption by public authorities and private users, the IEEE does not waive any rights in copyright to this document.aMore information is available at www.accellera.org. bIf interested in participating, please contact the VASG at stds-vasgieee.org or visit: http:/www.eda.org/vasg.IEC 61691-1-1:2011(E) -
44、xiv - g3IEEE Std 1076-2008Published by IEC under license from IEEE. 2008 IEEE. All rights reserved.Updating of IEEE documentsUsers of IEEE standards should be aware that these documents may be superseded at any time by the issuance of new editions or may be amended from time to time through the issu
45、ance of amendments, corrigenda, or errata. An official IEEE document at any point in time consists of the current edition of the document together with any amendments, corrigenda, or errata then in effect. In order to determine whether a given document is the current edition and whether it has been
46、amended through the issuance of amendments, corrigenda, or errata, visit the IEEE Standards Association website at http:/ieeexplore.ieee.org/xpl/standards.jsp, or contact the IEEE at the address listed previously.For more information about the IEEE Standards Association or the IEEE standards develop
47、ment process, visit the IEEE-SA website at http:/standards.ieee.org.ErrataErrata, if any, for this and all other standards can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically.Interpretat
48、ionsCurrent interpretations can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/interp/index.html.PatentsAttention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no
49、 position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying patents or patent applications for which a license may be required to implement an IEEE standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention.IMPORTANT NOTICE: This standard is not intended to assure safety, security, health, or environmental protection in all circumstances. Implementers of the standard are responsible for determining app
