VHDL-2008: Just the New Stuff
Published by Morgan Kaufmann
Publishers (an imprint of Elsevier), 2008, ISBN 978-0-12-374249-0
about this book
Front matter, including Contents
Sample - Chapter 5
Since VHDL-2008: Just the New Stuff was published, there have
been some late changes to the IEEE VHDL-2008 standard.
Unconstrained record types
The definition of an unconstrained record type on page 106 of the book
is not quite right. The correct definition, now included in the
standard, is that the record type has at least one composite element
and all composite elements are unconstrained.
Implicit application of the ?? operator
On page 132, the book lists the places where the condition operator
(??) is implicitly applied. The list omits guard expressions
of block statements. The VHDL standard has been updated to include
Reading out-mode signal parameters
On page 164, the book says that we can an read
out-mode signal parameter. The VHDL standard is now updated to
prohibit this, since allowing it introduced some subtle subtype
compatibility problems. The description in the book about reading
out-mode signal parameters should be disregarded. However, reading
out-mode variable parameters remains legal.
'Path_name and 'instance_name attributes
Section 9.17 on pages 221-222 describes updates to
the 'path_name and 'instance_name attributes. One
aspect that was overlooked was provision for unlabeled loops. The VHDL
standard has been updated to allow for an empty element in a pathname
corresponding to an unlabeled loop. This is similar to the way in
which a pathname can include an empty element corresponding to an
unlabeled process statement.
You might also be interested in the following books:
The Designer's Guide to VHDL, 3rd
The Student's Guide to VHDL, 2nd
Other sources of VHDL-related information:
The EDA Industry Working Groups Web Server
Usenet news group Frequently Asked Questions (FAQ) file
I would be pleased to hear your comments about the book. You can email
comments and errata to me at
Thanks, and happy reading!