19. Other Utility Programs

This chapter discusses some other utility programs available in the Ada environment.

19.1 Using Other Utility Programs With GNAT
19.2 The gnatpsys Utility Program
19.3 The gnatpsta Utility Program
19.4 The External Symbol Naming Scheme of GNAT
19.5 Ada Mode for emacs
19.9 Converting Ada files to html using gnathtml
19.10 Installing gnathtml

19.1 Using Other Utility Programs With GNAT

The object files generated by GNAT are in standard system format and in particular the debugging information uses this format. This means programs generated by GNAT can be used with existing utilities that depend on these formats.

In general, any utility program that works with C will also often work with Ada programs generated by GNAT. This includes software utilities such as gprof (a profiling program), gnatgdb (the FSF debugger), and utilities such as Purify.

19.2 The gnatpsys Utility Program

Many of the definitions in package System are implementation-dependent. Furthermore, although the source of the package System is available for inspection, it uses special attributes for parameterizing many of the critical values, so the source is not informative for the casual user.

The gnatpsys utility is designed to deal with this situation. It is an Ada program that dynamically determines the values of all the relevant parameters in System, and prints them out in the form of an Ada source listing for System, displaying all the values of interest. This output is generated to `stdout'.

To determine the value of any parameter in package System, simply run gnatpsys with no qualifiers or arguments, and examine the output. This is preferable to consulting documentation, because you know that the values you are getting are the actual ones provided by the executing system.

19.3 The gnatpsta Utility Program

Many of the definitions in package Standard are implementation-dependent. However, the source of this package does not exist as an Ada source file, so these values cannot be determined by inspecting the source. They can be determined by examining in detail the coding of `cstand.adb' which creates the image of Standard in the compiler, but this is awkward and requires a great deal of internal knowledge about the system.

The gnatpsta utility is designed to deal with this situation. It is an Ada program that dynamically determines the values of all the relevant parameters in Standard, and prints them out in the form of an Ada source listing for Standard, displaying all the values of interest. This output is generated to `stdout'.

To determine the value of any parameter in package Standard, simply run gnatpsta with no qualifiers or arguments, and examine the output. This is preferable to consulting documentation, because you know that the values you are getting are the actual ones provided by the executing system.

19.4 The External Symbol Naming Scheme of GNAT

In order to interpret the output from GNAT, when using tools that are originally intended for use with other languages, it is useful to understand the conventions used to generate link names from the Ada entity names.

All link names are in all lowercase letters. With the exception of library procedure names, the mechanism used is simply to use the full expanded Ada name with dots replaced by double underscores. For example, suppose we have the following package spec:

package QRS is MN : Integer; end QRS;

The variable MN has a full expanded Ada name of QRS.MN, so the corresponding link name is qrs__mn. Of course if a pragma Export is used this may be overridden:

package Exports is Var1 : Integer; pragma Export (Var1, C, External_Name => "var1_name"); Var2 : Integer; pragma Export (Var2, C, Link_Name => "var2_link_name"); end Exports;

In this case, the link name for Var1 is var1_name, and the link name for Var2 is var2_link_name.

One exception occurs for library level procedures. A potential ambiguity arises between the required name _main for the C main program, and the name we would otherwise assign to an Ada library level procedure called Main (which might well not be the main program).

To avoid this ambiguity, we attach the prefix _ada_ to such names. So if we have a library level procedure such as

procedure Hello (S : String);

the external name of this procedure will be _ada_hello.

19.5 Ada Mode for emacs

The Emacs mode for programming in Ada (both, Ada83 and Ada95) helps the user in understanding existing code and facilitates writing new code. It furthermore provides some utility functions for easier integration of standard Emacs features when programming in Ada.

19.6 General features:

• Full Integrated Development Environment :
  • support of 'project files' for the configuration (directories, compilation options,...)

  • compiling and stepping through error messages.

  • running and debugging your applications within Emacs.

• easy to use for beginners by pull-down menus,

• user configurable by many user-option variables.

19.7 Ada mode features that help understanding code:

• functions for easy and quick stepping through Ada code,

• getting cross reference information for identifiers (e.g. find the defining place by a keystroke),

• displaying an index menu of types and subprograms and move point to the chosen one,

• automatic color highlighting of the various entities in Ada code.

19.8 Emacs support for writing Ada code:

• switching between spec and body files with possible autogeneration of body files,

• automatic formating of subprograms parameter lists.

• automatic smart indentation according to Ada syntax,

• automatic completion of identifiers,

• automatic casing of identifiers, keywords, and attributes,

• insertion of statement templates,

• filling comment paragraphs like filling normal text,

For more information, please see See section 19.5 Ada Mode for emacs.

19.9 Converting Ada files to html using gnathtml

This Perl script allows Ada source files to be browsed using standard Web browsers. For installation procedure, see the section See section 19.10 Installing gnathtml.

Ada reserved keywords are highlighted in a bold font and Ada comments in a blue font. Unless your program was compiled with the gnatgcc -gnatx switch to suppress the generation of cross-referencing information, user defined variables and types will appear in a different color; you will be able to click on any identifier and go to its declaration.

The command line is as follow:

$ perl gnathtml.pl [switches] ada-files

You can pass it as many Ada files as you want. gnathtml will generate an html file for every ada file, and a global file called `index.htm'. This file is an index of every identifier defined in the files.

The available switches are the following ones :

-83

Only the subset on the Ada 83 keywords will be highlighted, not the full Ada 95 keywords set.

-cc color

This options allows you to change the color used for comments. The default value is green. The color argument can be any name accepted by html.

-d

If the ada files depend on some other files (using for instance the with command, the latter will also be converted to html. Only the files in the user project will be converted to html, not the files in the runtime library itself.

-D

This command is the same as -d above, but gnathtml will also look for files in the runtime library, and generate html files for them.

-f

By default, gnathtml will generate html links only for global entities ('with'ed units, global variables and types,...). If you specify the -f on the command line, then links will be generated for local entities too.

-l number

If this switch is provided and number is not 0, then gnathtml will number the html files every number line.

-I dir

Specify a directory to search for library files (`.ali' files) and source files. You can provide several -I switches on the command line, and the directories will be parsed in the order of the command line.

-o dir

Specify the output directory for html files. By default, gnathtml will saved the generated html files in a subdirectory named `html/'.

-p file

If you are using Emacs and the most recent Emacs Ada mode, which provides a full Integrated Development Environment for compiling, checking, running and debugging applications, you may be using `.adp' files to give the directories where Emacs can find sources and object files.

Using this switch, you can tell gnathtml to use these files. This allows you to get an html version of your application, even if it is spread over multiple directories.

-sc color

This options allows you to change the color used for symbol definitions. The default value is red. The color argument can be any name accepted by html.

19.10 Installing gnathtml

Perl needs to be installed on your machine to run this script. Perl is freely available for almost every architecture and Operating System via the Internet.

On Unix systems, you may want to modify the first line of the script gnathtml, to explicitly tell the Operating system where Perl is. The syntax of this line is :

#!full_path_name_to_perl

Alternatively, you may run the script using the following command line:

$ perl gnathtml.pl [switches] files