emacs/doc/misc/vhdl-mode.texi

\input texinfo   @c -*- texinfo -*-

@setfilename ../../info/vhdl-mode.info
@settitle VHDL Mode, an Emacs mode for editing VHDL code
@include docstyle.texi

@c Adapted from the VHDL Mode texinfo manual version 2 by Rodney J. Whitby.
@c Adapted from the CC Mode texinfo manual by Barry A. Warsaw.

@copying
This file documents VHDL Mode, an Emacs mode for editing VHDL code.

Copyright @copyright{} 1995--2008, 2010, 2012, 2015--2024 Free Software
Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being ``A GNU Manual,''
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation License.''

(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
modify this GNU manual.''
@end quotation
@end copying

@dircategory Emacs editing modes
@direntry
* VHDL Mode: (vhdl-mode).       Emacs mode for editing VHDL code.
@end direntry

@finalout

@titlepage
@title VHDL Mode
@sp 2
@subtitle A GNU Emacs mode for editing VHDL code.
@sp 2
@author Reto Zimmermann
@author @email{reto@@gnu.org}
@author Rod Whitby
@author @email{software.vhdl-mode@@rwhitby.net}

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top
@top VHDL Mode, an Emacs mode for editing VHDL code

@insertcopying
@end ifnottex

@menu
* Introduction::
* Getting Connected::
* New Indentation Engine::
* Customizing Indentation::
* Syntactic Symbols::
* Frequently Asked Questions::
* Getting the latest VHDL Mode release::
* Sample Init File::
* Limitations and Known Bugs::
* Mailing Lists and Submitting Bug Reports::
* GNU Free Documentation License:: The license for this documentation.
* Concept Index::
* Command Index::               Command Index
* Key Index::                   Key Index
* Variable Index::              Variable Index
@end menu

@node     Introduction
@chapter  Introduction
@cindex   Introduction

Welcome to VHDL Mode.  This is a GNU Emacs mode for editing files
containing VHDL code.

This manual will describe the following:

@itemize @bullet
@item
How to get started using VHDL Mode.

@item
How the indentation engine works.

@item
How to customize the indentation engine.

@end itemize

@findex vhdl-version
The major version number was incremented to 3 with the addition of
many new features for editing VHDL code to the new indentation engine,
which was introduced in major version 2.  To find the minor revision
number of this release, use @kbd{M-x vhdl-version @key{RET}}.

A special word of thanks goes to Rod Whitby, who wrote the
VHDL Mode indentation engine, and to Barry Warsaw, who wrote
the CC Mode indentation engine that formed the basis
thereof.  Their manuals were also the basis for this manual.

This manual is not very up-to-date.  It basically contains the
indentation machine documentation by Rod Whitby with only minor
adaptions.  A short documentation of the entire VHDL Mode is available
within the mode itself by typing @kbd{C-c C-h}.  Also, all commands and
customization of most variables are available through the menu, which
makes everything highly self-explaining.

@node     Getting Connected
@chapter  Getting Connected
@cindex   Getting Connected

To get started, simply visit a @file{.vhd} file in Emacs; or type
@kbd{M-x vhdl-mode @key{RET}}.

@node     New Indentation Engine
@chapter  New Indentation Engine
@cindex   New Indentation Engine

VHDL Mode has a new indentation engine, providing a simplified, yet
flexible and general mechanism for customizing indentation.  It breaks
indentation calculation into two steps.  First for the line of code being
indented, VHDL Mode analyzes what kind of language construct it's
looking at, then it applies user defined offsets to the current line
based on this analysis.

This section will briefly cover how indentation is calculated in
VHDL Mode.  It is important to understand the indentation model
being used so that you will know how to customize VHDL Mode for
your personal coding style.

@menu
* Syntactic Analysis::       Step 1 -- Syntactic Analysis
* Indentation Calculation::  Step 2 -- Indentation Calculation
@end menu

@node  Syntactic Analysis
@section  Syntactic Analysis
@cindex   Syntactic Analysis

@vindex vhdl-offsets-alist
@vindex offsets-alist @r{(vhdl-)}
@cindex relative buffer position
@cindex syntactic symbol
@cindex syntactic component
@cindex syntactic component list
@cindex relative buffer position
The first thing VHDL Mode does when indenting a line of code, is
to analyze the line, determining the @dfn{syntactic component list} of
the construct on that line.  A @dfn{syntactic component} consists of a
pair of information (in lisp parlance, a @emph{cons cell}), where the
first part is a @dfn{syntactic symbol}, and the second part is a
@dfn{relative buffer position}.  Syntactic symbols describe elements of
VHDL code, e.g., @code{statement}, @code{comment}, @code{block-open},
@code{block-close}, etc.  @xref{Syntactic Symbols}, for a complete list
of currently recognized syntactic symbols and their semantics.  Also,
the variable @code{vhdl-offsets-alist} contains the list of currently
supported syntactic symbols.

Conceptually, a line of VHDL code is always indented relative to the
indentation of some line higher up in the buffer.  This is represented
by the relative buffer position in the syntactic component.

It might help to see an example.  Suppose we had the following code as
the only thing in a VHDL Mode buffer @footnote{The line numbers
in this and future examples don't actually appear in the buffer.}:
@example
@group

  1: inverter : process
  2: begin
  3:   q <= not d;
  4:   wait on d;
  5: end inverter;

@end group
@end example

@kindex C-c C-x
@findex vhdl-show-syntactic-information
@findex show-syntactic-information @r{(vhdl-)}
We can use the command @kbd{C-c C-x}
(@code{vhdl-show-syntactic-information}) to simply report what the
syntactic analysis is for the current line.  Running this command on
line 4 of example 1, we'd see in the echo area:
@example

((statement . 28))

@end example

This tells us that the line is a statement and it is indented relative
to buffer position 28, which happens to be the @samp{q} on line 3.  If
you were to move point to line 3 and hit @kbd{C-c C-x}, you would see:
@example

((statement-block-intro . 20))

@end example

This indicates that line 3 is the first statement in a block, and is
indented relative to buffer position 20, which is the @samp{b} in the
@code{begin} keyword on line 2.

@cindex comment only line
Syntactic component lists can contain more than one component, and
individual syntactic components need not have relative buffer positions.
The most common example of this is a line that contains a @dfn{comment
only line}.
@example
@group

%%% TBD %%%

@end group
@end example

@noindent
Hitting @kbd{C-c C-x} on line 3 of the example gives us:
@example

((comment-intro) (block-intro . 46))

@end example

@noindent
so you can see that the syntactic component list contains two syntactic
components.  Also notice that the first component,
@samp{(comment-intro)} has no relative buffer position.

@node  Indentation Calculation
@section  Indentation Calculation
@cindex   Indentation Calculation

@vindex vhdl-offsets-alist
@vindex offsets-alist @r{(vhdl-)}
Indentation for the current line is calculated using the syntactic
component list derived in step 1 above (@pxref{Syntactic
Analysis}).  Each component contributes to the final total indentation
of the line in two ways.

First, the syntactic symbols are looked up in the @code{vhdl-offsets-alist}
variable, which is an association list of syntactic symbols and the
offsets to apply for those symbols.  These offsets are added to the
running total.

Second, if the component has a relative buffer position, VHDL Mode
adds the column number of that position to the running total.  By adding
up the offsets and columns for every syntactic component on the list,
the final total indentation for the current line is computed.

Let's use our code example above to see how this works.  Here is our
example again.
@example
@group

  1: inverter : process
  2: begin
  3:   q <= not d;
  4:   wait on d;
  5: end inverter;

@end group
@end example

@kindex TAB
Let's say point is on line 3 and we hit the @key{TAB} key to re-indent
the line.  Remember that the syntactic component list for that
line is:
@example

((statement-block-intro . 20))

@end example

@noindent
VHDL Mode looks up @code{statement-block-intro} in the
@code{vhdl-offsets-alist} variable.  Let's say it finds the value @samp{2};
it adds this to the running total (initialized to zero), yielding a
running total indentation of 2 spaces.

Next VHDL Mode goes to buffer position 20 and asks for the
current column.  Since the @code{begin} keyword at buffer position 20 is
in column zero, it adds @samp{0} to the running total.  Since there is
only one syntactic component on the list for this line, indentation
calculation is complete, and the total indentation for the line is 2
spaces.
Simple, huh?

Actually, the mode usually just does The Right Thing without you having
to think about it in this much detail.  But when customizing
indentation, it's helpful to understand the general indentation model
being used.

@vindex vhdl-echo-syntactic-information-p
@vindex echo-syntactic-information-p @r{(vhdl-)}
@cindex @key{TAB}
To help you configure VHDL Mode, you can set the variable
@code{vhdl-echo-syntactic-information-p} to non-@code{nil} so that the
syntactic component list and calculated offset will always be echoed in
the minibuffer when you hit @kbd{@key{TAB}}.


@ignore
@node  Indentation Commands
@chapter  Indentation Commands
@cindex   Indentation Commands

@strong{<TBD>}
@end ignore


@node     Customizing Indentation
@chapter  Customizing Indentation
@cindex   Customizing Indentation

@cindex @code{vhdl-set-offset}
@cindex set-offset (vhdl-)
The @code{vhdl-offsets-alist} variable is where you customize all your
indentations.  You simply need to decide what additional offset you want
to add for every syntactic symbol.  You can use the command @kbd{C-c
O} (@code{vhdl-set-offset}) as the way to set offsets, both
interactively and from your mode hook.  Also, you can set up
@emph{styles} of indentation.  Most likely, you'll find one of the
pre-defined styles will suit your needs, but if not, this section will
describe how to set up basic editing configurations.  @xref{Styles}, for
an explanation of how to set up named styles.

@cindex @code{vhdl-basic-offset}
@cindex basic-offset (vhdl-)
As mentioned previously, the variable @code{vhdl-offsets-alist} is an
association list between syntactic symbols and the offsets to be applied
for those symbols.  In fact, these offset values can be an integer, a
function or variable name, or one of the following symbols: @code{+},
@code{-}, @code{++}, @code{--}, @code{*}, or @code{/}.  The symbol
values have the following meanings:

@itemize @bullet

@item
@code{+}  --  1 x @code{vhdl-basic-offset}
@item
@code{-}  --  -1 x @code{vhdl-basic-offset}
@item
@code{++} --  2 x @code{vhdl-basic-offset}
@item
@code{--} --  -2 x @code{vhdl-basic-offset}
@item
@code{*}  --  0.5 x @code{vhdl-basic-offset}
@item
@code{/}  --  -0.5 x @code{vhdl-basic-offset}

@end itemize

@noindent
So, for example, because most of the default offsets are defined in
terms of @code{+}, @code{-}, and @code{0}, if you like the general
indentation style, but you use 2 spaces instead of 4 spaces per level,
you can probably achieve your style just by changing
@code{vhdl-basic-offset} like so (in your @file{.emacs} file):
@example

(setq vhdl-basic-offset 2)

@end example

To change indentation styles more radically, you will want to change the
value associated with the syntactic symbols in the
@code{vhdl-offsets-alist} variable.  First, I'll show you how to do that
interactively, then I'll describe how to make changes to your
@file{.emacs} file so that your changes are more permanent.

@menu
* Interactive Customization::
* Permanent Customization::
* Styles::
* Advanced Customizations::
@end menu

@node     Interactive Customization
@section  Interactive Customization
@cindex   Interactive Customization

As an example of how to customize indentation, let's change the
style of the example above from:
@example
@group

  1: inverter : process
  2: begin
  3:   q <= not d;
  4:   wait on d;
  5: end inverter;

@end group
@end example
@noindent
to:
@example
@group

  1: inverter : process
  2: begin
  3:     q <= not d;
  4:     wait on d;
  5: end inverter;

@end group
@end example

In other words, we want to change the indentation of the statements
inside the inverter process.  Notice that the construct we want to
change starts on line 3.  To change the indentation of a line, we need
to see which syntactic component affect the offset calculations for that
line.  Hitting @kbd{C-c C-x} on line 3 yields:
@example

((statement-block-intro . 20))

@end example

@findex vhdl-set-offset
@findex set-offset @r{(vhdl-)}
@kindex C-c O
@noindent
So we know that to change the offset of the first signal assignment, we need to
change the indentation for the @code{statement-block-intro} syntactic
symbol.  To do this interactively, just hit @kbd{C-c O}
(@code{vhdl-set-offset}).  This prompts you for the syntactic symbol to
change, providing a reasonable default.  In this case, the default is
@code{statement-block-intro}, which is just the syntactic symbol we want to
change!

After you hit return, VHDL Mode will then prompt you for the new
offset value, with the old value as the default.  The default in this
case is @samp{+}, so hit backspace to delete the @samp{+}, then hit
@samp{++} and @kbd{RET}.  This will associate an offset of twice the
basic indent with the syntactic symbol @code{statement-block-intro} in
the @code{vhdl-offsets-alist} variable.

@findex vhdl-indent-defun
@findex indent-defun @r{(vhdl-)}
To check your changes quickly, just enter @kbd{M-x vhdl-indent-defun} to
reindent the entire function.  The example should now look like:
@example
@group

  1: inverter : process
  2: begin
  3:     q <= not d;
  4:     wait on d;
  5: end inverter;

@end group
@end example

Notice how just changing the offset on line 3 is all we needed to do.
Since the other affected lines are indented relative to line 3, they are
automatically indented the way you'd expect.  For more complicated
examples, this may not always work.  The general approach to take is to
always start adjusting offsets for lines higher up in the file, then
re-indent and see if any following lines need further adjustments.

@node     Permanent Customization
@section  Permanent Indentation
@cindex   Permanent Indentation

@vindex vhdl-mode-hook
@cindex hooks
To make this change permanent, you need to add some lisp code to your
@file{.emacs} file.  VHDL Mode provides a @code{vhdl-mode-hook}
that you can use to customize your language editing styles.  This hook
gets run as the last thing when you enter VHDL Mode.

Here's a simplified example of what you can add to your @file{.emacs}
file to make the changes described in the previous section
(@ref{Interactive Customization}) more permanent.  See the Emacs
manuals for more information on customizing Emacs via hooks.
@xref{Sample Init File}, for a more complete sample @file{.emacs} file.

@example
@group

(defun my-vhdl-mode-hook ()
  ;; my customizations for all of vhdl-mode
  (vhdl-set-offset 'statement-block-intro '++)
  ;; other customizations can go here
  )
(add-hook 'vhdl-mode-hook 'my-vhdl-mode-hook)

@end group
@end example

For complex customizations, you will probably want to set up a
@emph{style} that groups all your customizations under a single
name.  @xref{Styles}.

The offset value can also be a function, and this is how power users
gain enormous flexibility in customizing indentation.  @xref{Advanced
Customizations}.

@node     Styles
@section  Styles
@cindex   Styles

Most people only need to edit code formatted in just a few well-defined
and consistent styles.  For example, their organization might impose a
``blessed'' style that all its programmers must conform to.  Similarly,
people who work on GNU software will have to use the GNU coding style on
C code.  Some shops are more lenient, allowing some variety of coding
styles, and as programmers come and go, there could be a number of
styles in use.  For this reason, VHDL Mode makes it convenient for
you to set up logical groupings of customizations called @dfn{styles},
associate a single name for any particular style, and pretty easily
start editing new or existing code using these styles.  This chapter
describes how to set up styles and how to edit your C code using styles.

@menu
* Built-in Styles::
* Adding Styles::
* File Styles::
@end menu


@node     Built-in Styles
@subsection  Built-in Styles
@cindex   Built-in Styles

If you're lucky, one of VHDL Mode's built-in styles might be just
what you're looking for.  Some of the most common VHDL styles are
already built-in.  These include:

@itemize @bullet
@item
@cindex IEEE style
@code{GNU} -- the coding style in the IEEE Language Reference Manual.

@end itemize

@findex vhdl-set-style
@findex set-style @r{(vhdl-)}
If you'd like to experiment with these built-in styles you can simply
type @kbd{M-x vhdl-set-style @key{RET}} in a VHDL Mode buffer.

You will be prompted for one of the above styles (with completion).
Enter one of the styles and hit @kbd{RET}.  Note however that setting a
style in this way does @emph{not} automatically re-indent your file.
@ignore
For commands that you can use to view the effect of your changes, see
@ref{Indentation Commands}.
@end ignore

Once you find a built-in style you like, you can make the change
permanent by adding a call to your @file{.emacs} file.  Let's say for
example that you want to use the @code{IEEE} style in all your
files.  You would add this:
@example
@group

(defun my-vhdl-mode-hook ()
  ;; use IEEE style for all VHDL code
  (vhdl-set-style "IEEE")
  ;; other customizations can go here
  )
(add-hook 'vhdl-mode-hook 'my-vhdl-mode-hook)

@end group
@end example

@noindent
@xref{Permanent Customization}.

@node     Adding Styles
@subsection  Adding Styles
@cindex   Adding Styles

@vindex vhdl-style-alist
@vindex style-alist @r{(vhdl-)}
@findex vhdl-add-style
@findex add-style @r{(vhdl-)}
If none of the built-in styles is appropriate, you'll probably want to
add a new style definition.  Styles are kept in the @code{vhdl-style-alist}
variable, but you probably won't want to modify this variable directly.
VHDL Mode provides a function, called @code{vhdl-add-style}, that you
can use to easily add new styles or update existing styles.  This
function takes two arguments, a @var{stylename} string, and an
association list @var{description} of style customizations.  If
@var{stylename} is not already in @code{vhdl-style-alist}, the new style is
added, otherwise the style already associated with @var{stylename} is
changed to the new @var{description}.  This function also takes an
optional third argument, which if non-@code{nil}, automatically
institutes the new style in the current buffer.

The sample @file{.emacs} file provides a concrete example of how a new
style can be added and automatically set.  @xref{Sample Init File}.

@node     File Styles
@subsection  File Styles
@cindex   File Styles

@cindex local variables
The Emacs manual describes how you can customize certain variables on a
per-file basis by including a @dfn{Local Variable} block at the end of
the file.  So far, you've only seen a functional interface to
VHDL Mode, which is highly inconvenient for use in a Local Variable
block.  VHDL Mode provides two variables that make it easier for
you to customize your style on a per-file basis.

@vindex vhdl-file-style
@vindex file-style @r{(vhdl-)}
@vindex vhdl-file-offsets
@vindex file-offsets @r{(vhdl-)}

The variable @code{vhdl-file-style} can be set to a style name string as
described in @ref{Built-in Styles}.  When the file is visited,
VHDL Mode will automatically set the file's style to this style
using @code{vhdl-set-style}.

@vindex vhdl-offsets-alist
@vindex offsets-alist @r{(vhdl-)}
@findex vhdl-set-offset
@findex set-offset @r{(vhdl-)}
Another variable, @code{vhdl-file-offsets}, takes an association list
similar to what is allowed in @code{vhdl-offsets-alist}.  When the file is
visited, VHDL Mode will automatically institute these offsets using
@code{vhdl-set-offset}.  @xref{Customizing Indentation}.

Note that file style settings (i.e., @code{vhdl-file-style}) are applied
before file offset settings (i.e., @code{vhdl-file-offsets}).


@node     Advanced Customizations
@section  Advanced Customizations
@cindex   Advanced Customizations

@vindex vhdl-style-alist
@vindex style-alist @r{(vhdl-)}
@vindex vhdl-basic-offset
@vindex basic-offset @r{(vhdl-)}
For most users, VHDL Mode will support their coding styles with
very little need for customizations.  Usually, one of the standard
styles defined in @code{vhdl-style-alist} will do the trick.  Sometimes,
one of the syntactic symbol offsets will need to be tweaked slightly, or
perhaps @code{vhdl-basic-offset} will need to be changed.  However, some
styles require a more advanced ability for customization, and one of the
real strengths of VHDL Mode is that the syntactic analysis model
provides a very flexible framework for customizing indentation.  This
allows you to perform special indentation calculations for situations
not handled by the mode directly.

@menu
* Custom Indentation Functions::
* Other Special Indentations::
@end menu

@node     Custom Indentation Functions
@subsection  Custom Indentation Functions
@cindex   Custom Indentation Functions

@cindex custom indentation functions
One of the most common ways to customize VHDL Mode is by writing
@dfn{custom indentation functions} and associating them with specific
syntactic symbols (@pxref{Syntactic Symbols}).  VHDL Mode itself
uses custom indentation functions to provide more sophisticated
indentation, for example when lining up selected signal assignments:
@example
@group

%%% TBD %%%

@end group
@end example

In this example, the @code{statement-cont} syntactic symbol has an
offset of @code{+}, and @code{vhdl-basic-offset} is 2, so lines 4
through 6 are simply indented two spaces to the right of line 3.  But
perhaps we'd like VHDL Mode to be a little more intelligent so
that it offsets the waveform descriptions relative to the signal
assignment operator in line 3.  To do this, we have to write a custom
indentation function which finds the column of signal assignment
operator on the first line of the statement.  Here is the lisp code
(from the @file{vhdl-mode.el} source file) that implements this:
@example
@group

(defun vhdl-lineup-statement-cont (langelem)
  ;; line up statement-cont after the assignment operator
  (save-excursion
    (let* ((relpos (cdr langelem))
	   (assignp (save-excursion
		     (goto-char (vhdl-point 'boi))
		     (and (re-search-forward "\\(<\\|:\\)="
					     (vhdl-point 'eol) t)
			  (- (point) (vhdl-point 'boi)))))
	   (curcol (progn
		     (goto-char relpos)
		     (current-column)))
	   foundp)
      (while (and (not foundp)
		  (< (point) (vhdl-point 'eol)))
	(re-search-forward "\\(<\\|:\\)=\\|(" (vhdl-point 'eol) 'move)
	(if (vhdl-in-literal (cdr langelem))
	    (forward-char)
	  (if (= (preceding-char) ?\()
	      ;; skip over any parenthesized expressions
	      (goto-char (min (vhdl-point 'eol)
			      (scan-lists (point) 1 1)))
	    ;; found an assignment operator (not at eol)
	    (setq foundp (not (looking-at "\\s-*$"))))))
      (if (not foundp)
	  ;; there's no assignment operator on the line
	  vhdl-basic-offset
	;; calculate indentation column after assign and ws, unless
	;; our line contains an assignment operator
	(if (not assignp)
	    (progn
	      (forward-char)
	      (skip-chars-forward " \t")
	      (setq assignp 0)))
	(- (current-column) assignp curcol))
      )))

@end group
@end example
@noindent
Custom indent functions take a single argument, which is a syntactic
component cons cell (@pxref{Syntactic Analysis}).  The
function returns an integer offset value that will be added to the
running total indentation for the line.  Note that what actually gets
returned is the difference between the column that the signal assignment
operator is on, and the column of the buffer relative position passed in
the function's argument.  Remember that VHDL Mode automatically
adds in the column of the component's relative buffer position and we
don't want that value added into the final total twice.

@cindex statement-cont syntactic symbol
@findex vhdl-lineup-statement-cont
@findex lineup-statement-cont @r{(vhdl-)}
Now, to associate the function @code{vhdl-lineup-statement-cont} with the
@code{statement-cont} syntactic symbol, we can add something like the
following to our @code{vhdl-mode-hook}:
@example

(vhdl-set-offset 'statement-cont 'vhdl-lineup-statement-cont)

@end example

@findex vhdl-indent-defun
Now the function looks like this after re-indenting (using @kbd{M-x
vhdl-indent-defun}):
@example
@group

%%% TBD %%%

@end group
@end example

@vindex vhdl-offsets-alist
@vindex offsets-alist @r{(vhdl-)}
Custom indentation functions can be as simple or as complex as you like,
and any syntactic symbol that appears in @code{vhdl-offsets-alist} can have
a custom indentation function associated with it.  Note however that
using many custom indentation functions may have a performance impact on
VHDL Mode.

@node     Other Special Indentations
@subsection  Other Special Indentations
@cindex   Other Special Indentations

@vindex vhdl-special-indent-hook
@vindex special-indent-hook @r{(vhdl-)}
One other variable is available for you to customize VHDL Mode:
@code{vhdl-special-indent-hook}.  This is a standard hook variable that
is called after every line is indented by VHDL Mode.  You can use
it to do any special indentation or line adjustments your style
dictates, such as adding extra indentation to the port map clause in a
component instantiation, etc.  Note however, that you should not change
@code{point} or @code{mark} inside your @code{vhdl-special-indent-hook}
functions.


@node  Syntactic Symbols
@chapter  Syntactic Symbols
@cindex   Syntactic Symbols

@vindex vhdl-offsets-alist
The complete list of recognized syntactic symbols is described in the
@code{vhdl-offsets-alist} variable.  This chapter will provide some
examples to help clarify these symbols.

@cindex -open syntactic symbols
@cindex -close syntactic symbols
Most syntactic symbol names follow a general naming convention.  When a
line begins with a @code{begin} or @code{end} keyword, the syntactic
symbol will contain the suffix @code{-open} or @code{-close}
respectively.

@cindex -intro syntactic symbols
@cindex -cont syntactic symbols
@cindex -block-intro syntactic symbols
Usually, a distinction is made between the first line that introduces a
construct and lines that continue a construct, and the syntactic symbols
that represent these lines will contain the suffix @code{-intro} or
@code{-cont} respectively.  As a sub-classification of this scheme, a
line which is the first of a particular block construct will contain the
suffix @code{-block-intro}.

@strong{<TBD> include the name and a brief example of every syntactic
symbol currently recognized}

@node  Frequently Asked Questions
@chapter  Frequently Asked Questions
@cindex   Frequently Asked Questions

@kindex C-x h
@kindex ESC C-\
@kindex ESC C-q
@kindex ESC C-u
@kindex RET
@kindex LFD
@findex newline-and-indent
@quotation

@strong{Q.} @emph{How do I re-indent the whole file?}

@strong{A.} Visit the file and hit @kbd{C-x h} to mark the whole
buffer.  Then hit @kbd{@key{ESC} C-\} to re-indent the entire region
which you've just marked.  Or just enter @kbd{M-x vhdl-indent-buffer}.
@sp 2

@strong{Q.} @emph{How do I re-indent the entire function?}

@strong{A.} Hit @kbd{@key{ESC} C-h} to mark the entire function.  Then
hit @kbd{@key{ESC} C-\} to re-indent the entire region which you've just
marked.
@sp 2

@strong{Q.} @emph{How do I re-indent the current block?}

@strong{A.} First move to the brace which opens the block with
@kbd{@key{ESC} C-u}, then re-indent that expression with
@kbd{@key{ESC} C-q}.
@sp 2

@strong{Q.} @emph{How do I re-indent the current statement?}

@strong{A.} First move to the beginning of the statement with
@kbd{@key{ESC} a}, then re-indent that expression with @kbd{@key{ESC}
C-q}.
@sp 2

@strong{Q.} @emph{I put @code{(vhdl-set-offset 'statement-cont 0)}
in my @file{.emacs} file but I get an error saying that
@code{vhdl-set-offset}'s function definition is void.}

@strong{A.} This means that VHDL Mode wasn't loaded into your
Emacs session by the time the @code{vhdl-set-offset} call was reached,
mostly likely because VHDL Mode is being autoloaded.  Instead
of putting the @code{vhdl-set-offset} line in your top-level
@file{.emacs} file, put it in your @code{vhdl-mode-hook}, or
simply add the following to the top of your @file{.emacs} file:
@example

(require 'vhdl-mode)

@end example

See the sample @file{.emacs} file @ref{Sample Init File} for
details.

@end quotation


@node  Getting the latest VHDL Mode release
@chapter  Getting the latest VHDL Mode release
@cindex   Getting the latest VHDL Mode release

The best way to be sure you always have the latest VHDL Mode release
is to join the @code{vhdl-mode-announce} mailing list.  If you are a
brave soul, and wish to participate in beta testing of new releases of
VHDL Mode, you may also join the @code{vhdl-mode-victims} mailing
list.  Send email to the maintainer @email{reto@@gnu.org} to join
either of these lists.

The official Emacs VHDL Mode Home Page can be found at
@uref{https://www.iis.ee.ethz.ch/~zimmi/emacs/vhdl-mode.html}.

@node  Sample Init File
@chapter  Sample Init File
@cindex   Sample init file

Most customizations can be done using the ``Customize'' entry in the
VHDL Mode menu, which requires no editing of the .emacs file.
If you want to customize indentation, here you go:

@example
;; Here's a sample .emacs file that might help you along the way.  Just
;; copy this region and paste it into your .emacs file.  You may want to
;; change some of the actual values.

(defconst my-vhdl-style
  '((vhdl-tab-always-indent        . t)
    (vhdl-comment-only-line-offset . 4)
    (vhdl-offsets-alist            . ((arglist-close    . vhdl-lineup-arglist)
                                      (statement-cont   . 0)
                                      (case-alternative . 4)
                                      (block-open       . 0)))
    (vhdl-echo-syntactic-information-p . t)
    )
  "My VHDL Programming Style")

;; Customizations for vhdl-mode
(defun my-vhdl-mode-hook ()
  ;; add my personal style and set it for the current buffer
  (vhdl-add-style "PERSONAL" my-vhdl-style t)
  ;; offset customizations not in my-vhdl-style
  (vhdl-set-offset 'statement-case-intro '++)
  ;; other customizations
  (setq tab-width 8
        ;; this will make sure spaces are used instead of tabs
        indent-tabs-mode nil)
  ;; key bindings for VHDL are put in vhdl-mode-map
  (define-key vhdl-mode-map "\C-m" 'newline-and-indent)
  )

(add-hook 'vhdl-mode-hook 'my-vhdl-mode-hook)
@end example

@node  Limitations and Known Bugs
@chapter  Limitations and Known Bugs
@cindex   Limitations and Known Bugs

@itemize @bullet
@item
Re-indenting large regions or expressions can be slow.

@ignore
@item
The index menu does not work on my XEmacs installation (don't know why).
@end ignore

@end itemize

@node  Mailing Lists and Submitting Bug Reports
@chapter  Mailing Lists and Submitting Bug Reports
@cindex   Mailing Lists and Submitting Bug Reports

@kindex C-c C-b
@findex vhdl-submit-bug-report
@findex submit-bug-report @r{(vhdl-)}
@cindex beta testers mailing list
@cindex announcement mailing list
To report bugs, use the @kbd{C-c C-b} (@code{vhdl-submit-bug-report})
command.  This provides vital information I need to reproduce your
problem.  Make sure you include a concise, but complete code example.
Please try to boil your example down to just the essential code needed
to reproduce the problem, and include an exact recipe of steps needed to
expose the bug.  Be especially sure to include any code that appears
@emph{before} your bug example.

For other help or suggestions, send a message to @email{reto@@gnu.org}.

Send an add message to @email{reto@@gnu.org} to get on the
@code{vhdl-mode-victims} beta testers list where beta releases of
VHDL Mode are posted.  Note that you shouldn't expect beta
releases to be as stable as public releases.

There is also an announce only list where the latest public releases
of VHDL Mode are posted.  Send an add message to
@email{reto@@gnu.org} to be added to this list.


@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include doclicense.texi


@node    Concept Index
@unnumbered Concept Index

@printindex cp


@node    Command Index
@unnumbered Command Index

Since all VHDL Mode commands are prepended with the string
@samp{vhdl-}, each appears under its @code{vhdl-<thing>} name and its
@code{<thing> (vhdl-)} name.
@iftex
@sp 2
@end iftex
@printindex fn


@node    Key Index
@unnumbered Key Index

@printindex ky


@node    Variable Index
@unnumbered Variable Index

Since all VHDL Mode variables are prepended with the string
@samp{vhdl-}, each appears under its @code{vhdl-<thing>} name and its
@code{<thing> (vhdl-)} name.
@iftex
@sp 2
@end iftex
@printindex vr

@bye