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Artek Ada v1.25
2024-07-08 18:31:49 +02:00
README for Artek Ada version 1.25 (revised Jan. 22, 1987)
Thank you very much for choosing Artek Ada.
This file contains information about additions and improve-
ments to Artek Ada. Please read it carefully.
NOTICE TO USERS OF EARLIER RELEASES
-----------------------------------
You cannot use libraries (ADA.ALB files) from previous
releases of the compiler with the new 1.25 compiler. You
will have to recompile your library units with the new
compiler. Any "old" units in the library will cause an error
message to appear. Also, old AXE files cannot be executed
using the new interpreter. This is because the A-code has
been modified slightly for better memory efficiency.
The file LINKINFO.TMP is no longer generated or supported by
the compiler. After library subprograms were introduced,
this file lost its purpose, and because it has been confusing
users, we decided to remove it entirely.
USING THE COMPILER WITH TWO DISKETTE DRIVES
-------------------------------------------
Artek Ada release 1.25 comes on three diskettes instead of
two as described in the User's Guide.
The first diskette, labeled "Compiler", and the diskette
marked "Utility 1" contain the Artek Ada compiler and associ-
ated files. You need only these two diskettes to use the
Artek Ada system. The third diskette, labeled "Utility 2",
contains Ada demonstration and sample source files. You do
not need to install this diskette in your two-diskette
system.
To use Artek Ada with two diskette drives, just follow the
instructions in the User's Guide, pretending that the
"Utility 2" diskette does not exist. Then, before using the
system for the first time, enter the command
path B:\ <ENTER>
This will tell the operating system to look for Artek Ada
system files on the B: drive as well as the A: drive.
Now, at the A> prompt, you can type apse <ENTER> just as nor-
mal, and you are in business. The operating system and the
APSE will automatically switch between drives when necessary.
For your convenience, you may want to put the above path com-
mand in a batch file, preferably AUTOEXEC.BAT, so that you do
not need to enter it each time you want to use Artek Ada.
Your Ada files will be stored on drive A, where approximately
80 Kbytes of diskette space are free. If you want to have a
look at some of the Ada source files on the Utility 2
diskette, just copy them over to drive A and compile the pro-
grams as usual. Note, however, that they will not fit all at
once.
DEVIATIONS FROM THE STANDARD NOT LISTED IN APPENDIX F
-----------------------------------------------------
Most of the following deficiencies will be remedied in future
updates. These updates will be made available to registered
users.
Main program parameters are ignored and should not be used.
Only the first 16 characters of an identifier are considered
significant when distinguishing between identifier names.
The compiler maximum line length is 255 characters. (This is
not a deviation from Standard Ada, since any reasonable line
length is allowed by the Standard.)
Renaming is not allowed for packages.
Type conversions are not allowed as OUT and IN OUT parame-
ters.
Ambiguous subprograms may be declared without error, but when
an attempt is made to call one of them, an error message is
generated.
Identical identifiers introduced by USE clauses do not hide
each other.
Use clauses applied to library units are not inherited in
secondary units (except subunits). This means that if you
WITH and USE TEXT_IO is a library package specification, you
will have to re-USE TEXT_IO in the body (although you do not
have to re-WITH).
The attributes IMAGE, VALUE, PRED, SUCC etc. cannot be re-
named as functions or be given as a default generic subpro-
gram parameter.
Files accessed by DIRECT_IO cannot have more than 65535
records. Each record can be up to 64K in size.
Artek Ada requires the body of a generic subprogram or pack-
age to be compiled before the subprogram or package is in-
stantiated.
Library generic packages cannot be instantiated at the out-
ermost level to give library packages.
Generic object parameters are not supported.
NEW PROGRAMS
------------
NATIVE CODE TRANSLATOR
The Artek Native Code Translator is now included with the
compiler. The Translator is contained in a file called
A86.EXE, with run-time libraries being located in the files
AR-SMALL.SYS and AR-LARGE.SYS. To access the translator from
the APSE, use the T (translate) command, as explained in the
User's Guide (page 49).
The translator takes a linked-and-ready AXE file as input and
produces MS-DOS/PC-DOS standard EXE files as output. In the
current release, it is not possible to generate OBJ files.
This will be included in a future release.
Programs should behave in exactly the same manner when
executed as translated EXE files as they did when
interpreted, only much faster. The only "incompatibility"
problem may occur because the translated code uses a wee bit
more heap space than the interpreted one; this is especially
apparent when you use constants of unconstrained types.
A tip to save disk and memory space: The translator examines
your program to see whether you use floating-point
calculations. If you do not, the small run-time library (AR-
SMALL.SYS) is linked with your program instead of the normal
one (AR-LARGE.SYS), for a savings of about 11 K bytes. This
is because the floating-point software emulator is not
needed. If your program contains just a few floating-point
operations, you may want to consider alternate programming
methods to eliminate those operations. The payoff is a
whopping 11 K bytes!
For speed-intensive programs, you may want to consider using
the /n (no checks) compiler option when you compile final
releases. This will increase execution speed by 5-25 %
depending on the nature of your program. However, out-of-
bounds array indices etc. will not be detected if you use
this option.
The A86 translator program can be invoked with command-line
options that are not documented in the User's Guide. Most of
these options, alas, have no effect in the current release.
The command-line options are as follows:
/i - Inline 8087/80287 code generation
If this switch is used, the compiler generates 8087 opcodes
directly instead of software emulator interrupts. This will
improve the speed of your floating-point routines slightly.
On the other hand, translating with the /i switch will
prevent your program from running on a computer that doesn't
have an math co-processor.
The advantages and disadvantages of the /i switch are summed
up in the following table:
FP programs | Without 8087/287 | With 8087/287
-------------------------------------------------------------
no /i option | Slow math, | Fast math,
| 11 Kb emulator | 11 Kb emulator
| overhead | overhead
-------------------------------------------------------------
/i option used | Program bombs | Fastest math
-------------------------------------------------------------
/o - Object file generation
This switch will be used in a future version of the
translator to instruct it to generate an OBJ file instead of
an EXE file. The OBJ file can then be linked with standard
MS-DOS linkers, to libraries which conform with the Microsoft
C or Pascal calling conventions. Currently, this option has
no effect.
/d - Debug information
When used in conjunction with the /o switch, this indicates
that debugging information such as line numbers, etc. should
be included in the generated OBJ file. This information is
required by debuggers such as SYMDEB and CodeView (trademarks
of Microsoft Corp.) Currently, this option has no effect.
/n - No stack checking
This option is used to prevent the translator from generating
a run-time-system call at the start of every subprogram in
order to check for stack or heap overflow. Currently, this
option is always assumed to be present, and no special code
is generated to check for overflow. The run-time system,
however, senses when the heap and the stack collide, and in
this case raises STORAGE_ERROR.
/l - Large data model
The translator by default uses a "P" memory model. This
means that programs can be up to 1 megabyte, while data space
is limited to 64 Kbytes. The limitation on data space is
because the a-code intermediate language used by Artek Ada
uses 16-bit pointers only. This will be expanded to 32 bits
in a future release. The /l option will then specify that
32-bit pointers should be used in the final EXE file also.
Currently, the option has no effect.
/1 - 80186 code generation
When this option is used, the compiler will optimize
generated code for the Intel 80186 microprocessor. This will
result in a space and time savings of 1-8 % depending on the
nature of your program. The drawback is that a program
compiled with this switch will not run on a 8088 or 8086
microprocessor.
/2 - 80286 code generation
This option is used to optimize code generation for the 80286
microprocessor. This is mainly advantageous for programs
which contain tasking. However, the /2 switch is at the
moment equal to the /1 switch, except that some optimization
is done for the 80827 math co-processor if the /i switch is
also present.
/3 - 80386 code generation
This option is currently equal to the /1 option.
For pragma NATIVE writers
-------------------------
If you write pragma NATIVEs, you need to know that the
calling environment described in the User's Guide has been
extended somewhat.
Any pragma NATIVEs you've already written will continue to
work on the interpreter as before. However, they will not
work in translated programs. To create pragma NATIVEs that
are portable between the interpreter and the translator,
please observe the calling conventions described below.
At the time when the pragma NATIVE code gets control, the SI
register is loaded with the address of the current
procedure's first parameter. The DI register contains the
address of the current procedure's first local variable.
Additionally, the DS, ES and SS segment registers all point
to the current data segment, so you do not have to use ES:
segment overrides all the time. You may destroy all data
registers in your routine except BP, which must be restored
to its original value if you overwrite it. Segment registers
should also be restored to their original contents.
An example is in order here. Take a look at the following
function:
function ADD (A, B : in INTEGER) return INTEGER is
RESULT : INTEGER;
begin
pragma NATIVE (...);
return RESULT;
end ADD;
Previously, your assembly language code might have looked
like this:
MOV AX, ES:[BP] ; Load A (at offset 0 in the current frame)
ADD AX, ES:[BP+2] ; Add B (at offset 2)
MOV ES:[BP+4], AX ; Store in RESULT (at offset 4)
The new, translator-portable code is as follows:
MOV AX, [SI] ; Load A (parameter at offset 0)
ADD AX, [SI+2] ; Add B (parameter at offset 2)
MOV [DI], AX ; Store in RESULT (variable at offset 0)
Or, even better, replace the last line with the STOSW
instruction.
AUTOMATIC RECOMPILATION FACILITY (ARF)
A new utility program is included in release 1.25. This is
the Automatic Recompilation Facility, or ARF.
The ARF finds out which Ada programs and modules are obsolete
and must be recompiled and/or relinked. It will either pre-
sent you with a list of the necessary operations, write a
batch file for you, or automatically compile and link the
relevant files without further intervention.
The ARF uses time and date information in the ADA.ALB library
file, as well as MS-DOS file dates, to calculate its results.
You must always set your system clock at boot-up for the ARF
to work correctly. (Of course, the best solution is to have
an automatic clock/calendar card in your computer.)
The ARF is invoked from the DOS command line by typing
ARF [/option]<ENTER>
where /option is one of the following:
/l : list the necessary operations to be performed
/b : create the batch file DOARF.BAT
/a : automatically compile and link all obsolete files.
If the option is omitted, the ARF is run in list (/l) mode.
Note that 1) running ARF in list mode and then typing in the
listed commands, 2) running ARF in batch mode and then typing
DOARF<ENTER>, and 3) running ARF in automatic mode are all
equivalent.
To accommodate the ARF, we added a new option ("Auto") to the
APSE. Pressing the A key when the main APSE menu is shown on
the screen invokes the ARF in automatic mode.
The ARF is a time and headache saver when writing complex
software with many inter-module dependencies.
The ARF is similar in concept to the UNIX and MS-DOS MAKE
utilities, except that module dependencies are calculated au-
tomatically. This means that you do not need to write a spe-
cial script file for the ARF to work.
A subtle point regarding source file names: When you compile
a program with Artek Ada, the source file name and path are
stored in the program library. This information is then used
by ARF to determine what the name of your original source
file was. If you rename source files or copy them from one
DOS subdirectory to another, ARF may have obsolete informa-
tion about your source file. In this case, you should recom-
pile your module manually, and ARF will remember the new
source file name and/or path.
COMPILER ENHANCEMENTS
---------------------
TASKING PROGRAMS CAN BE SYNTAX-CHECKED
The 1.25 compiler will compile programs containing most task
declarations and tasking statements. It will, however, not
generate any code for tasking constructs.
Syntax errors will be spotted and limited semantic checking
is performed.
The syntax checking is not yet perfect, especially if complex
tasking programs are being compiled.
BETTER MEMORY MANAGEMENT
Users of previous releases discovered that complex programs
would sometimes run out of memory after having been running
for some time. This was because the heap became too
fractured, preventing reuse of individual blocks, and slowly
filled all available memory space.
The 1.25 compiler has a greatly enhanced memory management
mechanism that is designed to put an end to problems of this
kind.
DYNAMIC ARRAYS
Dynamic arrays and dynamic aggregates are fully supported in
release 1.25. (For an example of dynamic aggregates, see the
program SAMPLE11.ADA on the Utility 2 diskette.)
IMAGE AND VALUE FOR ENUMERATION TYPES
The IMAGE and VALUE attributes are now fully implemented.
The ENUMERATION_IO package is included in TEXT_IO.
LIBRARY GENERIC SUBPROGRAMS
Release 1.25 fully supports library generic subprograms. Now
you can write for the last time those sort and search proce-
dures you've been writing over and over again in the past.
Make'em generic!
UNCHECKED PROGRAMMING
As a consequence of the addition of library generic subpro-
grams, we've been able to add UNCHECKED_DEALLOCATION and
UNCHECKED_CONVERSION. These two library generic subprograms
deallocate (dispose) an access object, and convert an object
from one type to another, respectively. UNCHECKED_CONVERSION
will only work if the two types are of the same size. Other-
wise, it raises CONSTRAINT_ERROR.
In true Artek fashion, the source code to these two subpro-
grams is provided on the Utility 2 diskette under the name of
UNCHECK.ADA.
PRAGMA ACODE
If you examine the source code for UNCHECK.ADA, you will see
that the bulk of the two procedures is written with a new
pragma, pragma ACODE. This pragma is similar to pragma
NATIVE, except that it allows you to directly insert A-code
into your program.
The ACODE pragma takes a list of integer constants as a pa-
rameter. The first of these is interpreted as an A-code, and
the following integers are interpreted as data bytes.
To aid you in writing ACODE pragmas, we included the source
file ACODES.ADA. ACODES is a package which contains constant
declarations for all the currently supported A-codes. You
will see how it is used in UNCHECK.ADA.
As an example, consider the following:
pragma ACODE (NOP, 00, 00, 00);
pragma ACODE (LOAD2);
This code fragment loads the 2-byte object at address 0,
level 0, onto the A-stack.
PRAGMA INCLUDE_BINARY
If you want to include long assembly-language routines in
your Ada programs, you will quickly become tired of entering
long and unreadable pragma NATIVEs. And there is indeed a
better way, called pragma INCLUDE_BINARY.
INCLUDE_BINARY allows you to tell the compiler to read a
binary file (most often a COM or BIN file) from the disk and
include it as if it were a gigantic pragma NATIVE.
The syntax is:
pragma INCLUDE_BINARY ("[filename.ext]");
The file name can include a drive letter and/or a
subdirectory specification. This pragma is allowed anywhere
a statement is allowed. The file name string must be a
constant and be enclosed within quotes or percent signs.
The file you specify will be included in the generated code,
verbatim, byte by byte.
To prepare a file for use with INCLUDE_BINARY, use an
assembler and the EXE2BIN utility to convert your EXE files
into MS-DOS COM or BIN format before you compile the Ada
program. Don't use an ORG statement in your assembler source
file.
A typical command sequence to prepare a binary file for
inclusion in an Ada program is as follows:
MASM binfile; -- Assuming the Microsoft(R) Macro Assembler
LINK binfile; -- Ignore stack warning message from linker!
EXE2BIN binfile -- Convert binfile.exe to binfile.bin
ADA adaprog
- assuming that adaprog.ada contains the line
pragma INCLUDE_BINARY ("binfile.bin");
If the file you specify doesn't exist, the compiler gives an
error message and skips the pragma.
The same considerations apply for INCLUDE_BINARY code as for
NATIVE code, with regards to register usage, parameter
addresses, etc.
PRAGMA SUPPRESS
The compiler now has a pragma which suppresses all run-time
CONSTRAINT_ERROR checks. This pragma is as follows:
pragma SUPPRESS (ALL_CHECKS);
The effect is equivalent to specifying the /n option when the
compiler is started (see User's Guide, page 29).
The pragma SUPPRESS (NO_CHECKS) will reinstate constraint
checking.
CONDITIONAL COMPILATION
The compiler now optimizes if-statements with static condi-
tions so that no code is generated for then/else-branches
that would always be skipped anyway. This allows conditional
compilation of program parts, since you can trust that the
code you don't need won't be included in the final file. As
an example of this consider
DEBUG : constant BOOLEAN := TRUE;
if DEBUG then
PUT_LINE ("VAR is" & INTEGER'IMAGE (VAR));
end if;
If DEBUG is not TRUE, no code at all is generated for the if-
statement.
ERRORLEVEL RETURN FOR BATCH PROCESSING
The compiler now returns a status code when compilation is
finished. This status code can be interrogated with the IF
ERRORLEVEL n batch command.
The codes are as follows:
0 - Compilation was successful with no errors and no warn-
ings.
2 - Warnings were given, but no errors were found.
4 - Errors were found. Fix and recompile.
These return codes are compatible with MS-Pascal (R) and
other common compilers.
BLINKING ASTERISK DURING COMPILATION
If you do not specify the /listsource option when you com-
pile, the compiler can appear dead for a long period of time.
This is because Artek Ada utilizes the available memory in
your computer to the fullest extent to save disk I/O. To
assure you that all is well during compilation, an asterisk
blinks on your screen while the compiler is working.
Even if the asterisk stops blinking momentarily, give the
compiler a chance. Resolving the overloading in a very com-
plex expression can take up to 20 seconds on a PC.
VERSION 1.00 AC FILES NO LONGER REQUIRED
After library subprograms were introduced, the compiler was
changed so that all compiled subprograms are entered directly
into the program library instead of being written to an AC
file.
Therefore, AC files are no longer required or supported.
Any library subprogram can be linked to create an executable
file (AXE file) by typing LINKLIB [name of program]. You
should, however, beware of making subprograms which have
parameters into AXE files.
AUTOMATIC DISPOSE
Dynamic data are now automatically deallocated from the heap
when the access type in question goes out of scope. Note
that this means that if you have a library package which
declares an access type, objects of that type are never deal-
located, because the type never goes out of scope (except
when the program finishes, of course.) If you want to deal-
locate an object of such a type, use UNCHECKED DEALLOCATION.
SMALL BITS
The following "small bits" have been implemented: Block
names, quotes within string constants, return statement
within procedures (previously only for functions), exit from
blocks inside loops, very nice checking of CASE choices (Try
it sometime! Write a program with missing CASE choices and
watch how the compiler handles them), no more "intermodule
fixup" errors in generics, increased accuracy in internal
math operations, negative index values in constrained type
declarations, and more!.
LINKER ENHANCEMENTS
-------------------
Export and import of sublibraries has been added, a full
library directory facility, deletion of modules by wild
cards, and more. The additions are explained below.
MORE USER-FRIENDLINESS (we hope)
All linker/librarian options may now be specified in full or
partially at your discretion. This means that you can type
linklib /delete or linklib /del or linklib /d; it all means
the same.
If you don't remember a linklib command, just type linklib
/help (/h will do) to obtain a full listing of the available
options.
LIBRARY MODULE DELETION
The Artek Linker/Librarian has an undocumented option, /d,
which allows you to delete modules from the Ada library.
To delete a module called MODULENAME, enter
linklib MODULENAME /delete
Wild cards can be used to specify multiple modules. This is
explained below. See "EXPORT AND IMPORT OF SUBLIBRARIES."
LIBRARY REORGANIZATION
Due to the file structure used for the library, the ADA.ALB
file does not shrink in size even if you delete modules from
the library. If you want to pack the library file down to
its REAL size, use the new switch on the linker:
linklib /reorg -- This can be shortened to /r
This will write a new ADA.ALB library file which contains no
empty space. If the linker runs out of disk space during the
reorganization, it will give an error message and leave the
original file intact.
EXPORT AND IMPORT OF SUBLIBRARIES
In release 1.25 of Artek Ada, you can transfer a-code object
modules between libraries. This is done by using two new
options in the linker, /export and /import.
This feature can be used to transfer object module libraries
between programmers, or to distribute modules for Artek Ada
in object form, or to save space in the main ADA.ALB. Note
that the 1.25 compiler can only read and write the main
library, ADA.ALB.
To export a module from the main ADA.ALB library, type
linklib [modulename1+modulename2+...+modulenameN] /export
<ENTER> (not including the square brackets; no spaces between
the module names and plus-signs)
A new library file will be created with the name
[modulename1].ALB, containing the module(s) you specified.
Any previous ALB file with the same name is overwritten.
If you specify modules that are not found in the library,
they are simply ignored and not exported to the final
library. This can be used to name sublibraries, as shown in
the examples below.
The asterisk ("*") is allowed as a "wild card" in module
names. Thus, if you ask linklib to export gks*, it will put
all modules whose name begin with "gks" in the new subli-
brary.
To import a sublibrary into ADA.ALB, type
linklib [libraryname] /import <ENTER> (no square brackets)
This will import the library whose file name is
[libraryname].ALB into the main ADA.ALB library. Any modules
which previously existed in ADA.ALB with the same name as an
imported module are deleted. Only one library name is
allowed at a time; you cannot string them together with plus
signs.
A few examples are in order:
linklib text_io /export
This command will export the text_io module (specification
and body) into a new sublibrary called TEXT_IO.ALB.
linklib text_io+direct_io+sequential_io /e
This will export all the mentioned i/o modules into a new
sublibrary called TEXT_IO.ALB.
linklib iolib+text_io+direct_io+sequential_io /e
Assuming that the module iolib is not found in the library,
this will copy text_io, direct_io and sequential_io into a
sublibrary called IOLIB.ALB.
linklib gks*+graphics* /e
This command exports all modules whose names begin with "gks"
or "graphics" into the sublibrary GKS.ALB.
linklib gks /import
This will import the sublibrary GKS.ALB back again into
ADA.ALB.
LDIR REPLACED BY LINKLIB /LIST
The old LDIR command to list library contents has been dis-
continued. Now, its function is performed by the /list
option on the linker/librarian. This change is transparent
to users of the APSE. The M (modules) command works as
before. The difference is that it now invokes linklib
instead of ldir.
You can now list the contents of sublibraries as well as the
main ADA.ALB library. To list the contents of a sublibrary
called GKS.ALB, type
linklib gks /l <ENTER>
If you don't specify a library name, ADA.ALB is assumed.
DEBUGGER ENHANCEMENTS
---------------------
The Artek Interpreter/debugger has been enhanced greatly.
The main added features are the following:-
- Source-level debugging
- Post-mortem debugging
- Exception trapping
- Call stack display
- Heap block display
They are documented below.
SOURCE DEBUGGING
To enable source debugging for a particular compilation unit,
compile it with the /d (debugging) switch. The compiler will
generate an ADB file (Ada DeBug), which contains source line
numbering information.
To debug a program, just invoke the interpreter/debugger
AI.EXE with the /d (debugging) switch, or use the D command
from the APSE. The debugger will automatically locate and
load the available debugging information. You can see which
modules of a program have source debugging available by
entering the M (modules) command within the debugger. The
text "(source debug)" will appear after the names of all mod-
ules for which an ADB file is available.
If the debugger finds an ADB file which is older than the
corresponding source file, it will issue a warning. If you
have indeed edited the source file and subsequently compiled
it without the /d switch, the debugger may not be able to lo-
cate the source information correctly. In this case, either
recompile the offending unit with a /d switch, or delete the
ADB file. The latter removes source debugging for the unit
in question.
Once the debugger has been started, it shows you the current
source line in high intensity, as well as the A-code to be
executed next. You can single-step and trace, and the debug-
ger will show you the relevant source lines as the code for
them is executed.
Every time the program flow leaves one module and enters
another, the debugger displays the name of the module en-
tered.
To view the source code for a particular module, use the new
V (view) command. You will be asked for a module name and a
line number. You only have to enter enough characters to
make the module name unique. When the correct module name is
shown on the screen, press ENTER or a colon (":"). Then,
enter the line number you want to view from.
The debugger will show a default module name and line number.
If you want to use either or both of those, press the ENTER
key immediately instead of entering data. The default will
then be entered automatically.
The current release of the debugger does not support the
Backspace key while entering a module name. If you press an
incorrect key, you'll have to start all over again.
To set a breakpoint at a particular source line, use the B
(breakpoint) command. Then follow a similar procedure to the
one described for the view command.
Note that in the current release, the debugger will sometimes
stop on a breakpoint one instruction earlier than expected.
This is a minor annoyance and will be corrected in a future
release.
The debugger will display a highlighted "BP=>" symbol in
front of a line on which a breakpoint is set.
Note that you must have the ANSI.SYS driver installed in your
CONFIG.SYS file for highlighting and colors to work correctly
in the debugger.
POST-MORTEM DEBUGGING
Post-mortem debugging has also been added. Now, after a pro-
gram has finished execution, either normally or because of an
exception, you are presented with the post-mortem debugger
prompt "Post-mortem>". You are then allowed to use all the
normal debugger commands except Trace, Single-step and Go.
These commands have no effect in post-mortem mode.
To exit to the operating system, use the Quit command.
EXCEPTION TRAPPING
The E command, for Exception trap toggle, has been added. To
enable exception trapping, give the E command while at the
debugger prompt. To disable it, press the E key again.
Exception trapping, when enabled, causes the debugger to stop
execution whenever an exception is raised and wait for your
command. It is similar to setting a breakpoint at every
RAISE statement (but additionally, implicit exceptions such
as division by zero are trapped).
When you are at an exception trap point, you can Single-step,
Trace or Go, as usual.
Exception trapping is very useful when you have a spurious
exception appearing somewhere in your program and you want to
know exactly where it was originally raised.
CALL STACK DUMP
The C ("Call stack dump") command has also been added to the
debugger. This command dumps the current procedure call
stack on the screen.
A typical dump looks as follows:
Lv Address ExcH DynL SL
02 00 0134 0000 0049 01
01 01 872A 88C0 004B 00
00 00 0B4F 0000 0000
The first column, Lv, indicates the current (dynamic) call
level. The "02" in this case means that procedure nesting is
two levels deep at the moment.
The second column, Address, gives the number of the calling
module and the return address in that module. For a list of
currently active modules and their numbers, press M for the
Modules command.
The third column gives the address of the exception handler
which was in effect at the point of the call.
The fourth column, DynL, is the beginning of the frame of the
calling procedure. This will probably only be of interest to
seasoned A-code hackers.
The last column, SL, gives the static link to the next stati-
cally enclosing frame. For a technical discussion about the
function of the static link, we refer you to Niklaus Wirth's
book Algorithms+Data Structures=Programs (Prentice Hall,
1976).
HEAP BLOCKS DISPLAY
The H (heap dump) command now displays heap data in an easy-
to-understand block format, complete with block size and
linkage information. Each block is marked "Free" or
"Temporary" if it is on the system free-list or temporary-
list, respectively. Blocks on the free-list have been
disposed and may be reused by the heap allocator. Blocks on
the temporary-list are for intermediate results from
expression evaluation and subprogram calls and will be freed
when no longer in use.
REGISTER DUMP
The r (register dump) command now shows the current heap
pointer (the address of the beginning of the heap) and the
amount of free memory remaining between the stack and the
heap. Also, the number of free bytes within the heap itself
is displayed.
EDITOR ENHANCEMENTS
-------------------
WINDOWING
The Artek Editor now has multi-window, multi-file editing
capabilities. To open a new window, use the ESC W O (window
open) command. You will be asked whether the new window
should be horizontal or vertical. Finally, you are asked
where you want the new window border to be placed on the
screen.
To close a window, type ESC W C.
A window can be moved by using the ESC W M command. This
allows you to use the cursor to point to the window edge to
move. When you have selected the edge, move the cursor to
the place where it should be placed and type ENTER. The edi-
tor will move the window edge to the desired place.
To move between windows, press function key F1 and use the
cursor keys to point to the window which you want to move to.
You can select a new buffer for editing by typing ALT-N or
ESC N. The next buffer in line will be displayed in the cur-
rent window. There are 10 buffers available.
ESC P or ALT-P can be used to select the previous buffer for
editing.
To load a file into a new buffer, use the ESC F A (File Add)
command. This will load a file from disk into a previously
empty buffer.
The editor always displays the name of the current workfile
in the lower right corner of the screen. It is preceded by a
digit and a colon (for example 0:example.ada). The digit
indicates which buffer you are working on at the moment, from
zero to nine.
NEW EDITING FUNCTIONS
New editing functions include Cut to end of line, Move line
to center of screen and Delete line. They are described
below.
To delete ("cut") the text to the right of the cursor in
the current line, press Alt and c simultaneously.
To move the current line to the center of the screen,
scrolling the screen if necessary, press Alt-b. This will
bring the surrounding program text into view.
To delete the current line and close up the vacated space,
press the Ctrl and BACKSPACE keys at the same time.
The Ada Editor now contains several Ada-specific features.
You can comment and decomment a block, indent and outdent
blocks, and search for matching parenthesis.
To comment an Ada block, select the block in the normal way
using function key F6 and the cursor keys. Then, type + (the
plus key). There are two plus keys on the standard IBM key-
board; either one will do the trick.
You will see that the marked block is commented out by in-
serting two hyphens at the start of every line.
To remove the comment hyphens from a program block, select
the block and type - (the minus key).
To indent a program block, select the block and press the TAB
key. The TAB key is located above the CTRL key on the stan-
dard IBM keyboard.
To "outdent" a program block, select the block and press
SHIFT and TAB at the same time.
To find corresponding left and right parenthesis in a
program, just place the cursor on a parenthesis and press
F10. The editor will automatically highlight the text
between matching parenthesis.
As a matter of fact, you can position the cursor anywhere
between a pair of parenthesis and press F10. The editor
will still highlight the correct block of text.
If there is a parenthesis mismatch and the editor cannot
find a corresponding parenthesis, a beep will be heard and
the editor does not highlight a program block.
SCREEN SYNCHRONIZATION OPTIONAL
If you have a color graphics card, it may produce flicker
and "snow" on the screen when text is scrolled. To prevent
this, use the Screen Sync field in the editor Options as
detailed below.
After invoking the editor, enter ESC O (letter O) for
Options, use the CURSOR DOWN key to move to the Screen Sync
field, and set it to Y (for Yes). Note that after this,
the editor will slow down considerably, since it waits for
the screen's vertical retrace to occur everytime data is
written.
APSE ENHANCEMENTS
-----------------
Five commands have been added to the APSE, and one command
has been renamed. The five new commands are: Auto, for
invoking the ARF; Fork, for executing DOS commands without
leaving the APSE; Help, for displaying a help screen;
Redirect, to output compiler listings etc. to a printer or to
a file; and finally setUp (invoked by typing U) to select
screen colors and other system defaults. The renamed command
is Run, which is now called eXecute (invoked by typing X).
These additions and changes are documented below.
FORK COMMAND ADDED
You can now execute DOS commands without leaving the APSE.
The F (fork) command has been added for this purpose.
After you press F, the APSE will ask you for the DOS command
which you want to execute. If you press ENTER without enter-
ing a command, you will be taken into COMMAND.COM with the
drive> prompt. (To exit to the APSE again, enter EXIT and
press the ENTER key.) If you type a command, however, the
APSE will execute the command as if you had typed it at the
drive> prompt.
HELP SCREEN AVAILABLE
By typing H for Help while inside the APSE, you can now
obtain a screenful of information about the various APSE com-
mands, compiler options, and more.
SETUP ADDED IN APSE AND EDITOR
You can now decide once and for all which colors you want the
APSE and the Editor to use for text on the screen. Also,
screen synchronization may be permanently set.
If you don't want to use Artek's AE editor, you can set that
up in the APSE, too. Also, source and object file paths may
be defined to be something else than the default directory.
All this is done through the new setUp commands (invoked by
pressing U) in the APSE and the Editor.
REDIRECTION ADDED TO THE APSE
We have added the Redirect command to the APSE. This command
allows you to specify a file into which compiler output is to
be redirected. Also, the output of the Show and Modules com-
mands is redirected to this file.
This allows you to list the compiler output to a printer, or
to a text file.
The Run command had to be changed because of the naming con-
flict and is now called eXecute. It is invoked by typing X.
DEFAULT ENTRY TO EDITOR AFTER UNSUCCESSFUL COMPILATION
If you are using the APSE and the compiler finds an error in
your program, you will be asked immediately after the compi-
lation terminates whether you want to invoke the editor or go
back to the APSE. By pressing E, you will load the editor
without having to go to the APSE first. Press any other key
to return to the APSE as normal.
DISASSEMBLER ENHANCEMENTS
-------------------------
LIBRARY NAME NOT REQUIRED
The A-Code disassembler now always disassembles from the main
Ada library. Therefore, the optional library parameter has
been removed and the library ADA.ALB is automatically
searched for the module you specify.
NEW INCLUDED SOFTWARE
---------------------
MEMORY PACKAGE ALLOWS 640 K FOR DATA
We now include a new package, MEMORY.ADA, with the compiler.
This is a generic package which allows you to use all the
available RAM in your computer (excluding MS-DOS and the run-
ning program itself) for data within Ada programs.
The package functions similarly to DIRECT_IO. You begin by
instantiating it for the data type you wish to use. Then,
you call an ALLOCATE procedure to tell MEMORY how many pieces
of your data record you want to be able to store. After
these formalities have been fulfilled, you can READ and WRITE
data to "records" in memory, just as if the memory were con-
figured as an array. The only difference is that you have to
use READ and WRITE instead of normal assignment and indexing.
After use, you can DEALLOCATE the memory, and you can even
MODIFY_ALLOCATION if you find that you need more or less mem-
ory than originally anticipated.
The MEMORY package is documented with comments and an exam-
ple. See the source file MEMORY.ADA.
In the future, it is possible to add the Lotus-Intel-Mi-
crosoft (trademarks) Expanded Memory Standard and IBM AT
Extended memory access in the MEMORY package, while keeping
the same specification.
MATH PACKAGE
Release 1.25 includes a comprehensive package of basic mathe-
matical functions. Included are square roots, exponentials,
logarithms, and trigonometric functions complete with hyper-
bolic and inverse functions.
The specification of the MATH package is derived from Ada
Letters (the publication of ACM SigAda). It is a generic
package, ready to instantiate for your favorite FLOAT type.
Source code is included in the file MATH.ADA. You will
notice that many of the functions are written with high-speed
pragma NATIVEs. The MATH library uses an 8087/80287
coprocessor if available or the emulation library if not.
ENHANCED DOS_INTERFACE
The DOS_INTERFACE package has been enhanced with several low-
level utility subprograms. They are as follows:
function CURRENT_DATA_SEGMENT return WORD;
This function returns the value of the DS segment register.
It is provided for convenience when assigning to the ES field
of the REG_8086 structure in certain DOS calls.
procedure MERGE_REGISTERS (LO, HI : in BYTE; REG : out WORD);
Assigns a 16-bit register with two 8-bit register halves.
Example: MERGE_REGISTERS (16#00#, 16#4C#, REG . AX);
This will set AX to 16#4C00#.
procedure SPLIT_REGISTER (REG : in WORD; LO, HI : out BYTE);
Splits a 16-bit register into two 8-bit halves. Example:
SPLIT_REGISTER (16#4C00#, LOWPART, HIGHPART);
This will set LOWPART to 16#00# and HIGHPART to 16#4C#.
procedure POKE (SEGMENT, OFFSET : in WORD; VALUE : in BYTE);
Writes the VALUE to memory at address SEGMENT:OFFSET. POKE
(16#B000#, 16#0000#, 65) will put an A at the start of IBM PC
screen memory.
procedure POKE_WORD
(SEGMENT, OFFSET : in WORD; VALUE : in WORD);
Similar to POKE, except that a 16-bit value is written
instead of an 8-bit value. The low 8 bits of the value are
written to offset OFFSET, and the high 8 bits are written to
OFFSET+1.
function PEEK (SEGMENT, OFFSET : in WORD) return BYTE;
Reads an 8-bit BYTE value from memory at address
SEGMENT:OFFSET. FIRSTBYTE := PEEK (16#B000#, 16#0000#); sets
FIRSTBYTE to the ASCII value of the first character in the
IBM PC screen memory.
function PEEK_WORD (SEGMENT, OFFSET : in WORD) return WORD;
Similar to PEEK, except that a 16-bit value is read. The low
8 bits of the value are read from SEGMENT:OFFSET, while the
high 8 bits are read from SEGMENT:OFFSET+1.
procedure PORT_OUT (PORT : in WORD; VALUE : in BYTE);
Outputs a byte to the I/O port whose number is in PORT. Port
numbers and values are very hardware-specific.
procedure PORT_OUT_WORD (PORT : in WORD; VALUE : in WORD);
Outputs a word to the I/O port whose number is in PORT.
function PORT_IN (PORT : in WORD) return BYTE;
Inputs a byte from the I/O port whose number is in PORT.
function PORT_IN_WORD (PORT : in WORD) return WORD;
Inputs a word from the I/O port whose number is in PORT.
Also, a new field has been added to the REGS_8086 record.
This field, ES, contains the value of the ES segment reg-
ister.
The source code for DOS_INTERFACE can be found in the file
DOSINT.ADA on the Utility 2 diskette.
SCREEN INPUT/OUTPUT PACKAGES AND SUBPROGRAMS
On the Utility 2 diskette, we have included the library sub-
programs QPUT and QGET. These subprograms have the following
specifications:
procedure QPUT (S : in STRING);
procedure QGET (C : in out CHARACTER);
QPUT uses a special DOS interrupt to achieve fast console
output. QGET returns a character typed at the console, in-
cluding extended ASCII codes, control characters, etc. No
filtering is done.
The package CON_IO contains several utility subprograms for
manipulating the display. Among others, cursor addressing,
video attributes and colors are supported through calls to
this package. Boxes can easily be drawn on the screen using
the BOX procedure. The file CONIO.ADA on Utility Diskette 2
contains commented source code for this package. Also, an
example of its use can be found in the MAIL.ADA program
described below.
SAMPLE ADA PROGRAMS
On the Utility 2 diskette, you will find 12 sample Ada pro-
grams ready to compile. This will get you started with Artek
Ada. The samples are named SAMPLE1.ADA through SAMPLE12.ADA.
Also included is a demonstration program, MAIL, which demon-
strates the use of the CON_IO console I/O package. This
program allows you to enter, modify and view names in a
mailing list.
TECHNICAL NOTES
---------------
"GOTCHA!" WITH LIBRARY SUBPROGRAM SPECIFICATIONS AND BODIES
Library subprograms are stored in the program library in two
parts: the specification and the body. The specification
may be separately compiled. When you submit a subprogram
body for compilation, the compiler checks the library for a
corresponding specification. If a specification is found,
there must be an exact match between its parameter names,
types and modes, and those of the body. If this is not the
case, an error message is generated. To get rid of the error
message, you must either delete the offending subprogram from
the program library before you recompile, or insert a
separate subprogram specification before the body in your
source file.
The same gotcha can also apply if you have an old specifi-
cation in your library which has WITHed some program units
you no longer use. These units will be included in the final
AXE and/or EXE file, much to your annoyance.
The easiest way to find out whether any unwanted modules have
crept into an AXE file is to invoke the debugger (with the
name of the file as a parameter) and use the Modules command.
The same solution applies as above: delete the old subpro-
gram from the library before you recompile or write out the
subprogram specification explicitly yourself and include it
in the source file just before the body.
AUTO-SENSING OF 8087/80287 COPROCESSOR
The Artek Interpreter now automatically detects the presence
of an 8087/80287 math coprocessor and uses it if present. If
not, a software emulator executes math instructions.
ERRATA
------
The following errors have been found in the Artek Ada User's
Guide:
Page 24:
The editor keys <CTRL PGUP> and <CTRL PGDN> are juxtaposed.
Actually, <CTRL PGUP> stands for "Cursor to previous error in
file" and <CTRL PGDN> stands for "Cursor to next error in
file".
Pages 34 and 185:
The constant SYSTEM . STORAGE_UNIT is incorrectly given as
16. Since the 8086/88/186/286 family of microprocessors is
byte-addressable, we decided that it would be more convenient
if SYSTEM . STORAGE_UNIT were given the value 8 instead of
16. This affects for example the use of the SIZE attribute,
which returns the size of its prefix in bits. To obtain the
size in bytes, divide the result by SYSTEM . STORAGE_UNIT.
Page 65:
The IN A-code has its parameters listed in the wrong order.
The correct order is:
WORD Operand
WORD Lower bound of range
WORD Upper bound of range
Pages 79 and 106:
In the text about parameter passing with the CALL and LCALL
A-codes, "Mode in or out" should be "Mode in out or out".
Page 99:
The result for the DUP1 A-code lists only one "BYTE Operand".
The result is in fact twice "BYTE Operand".
Page 108:
The operation of the HCOPY A-code has been changed. Its
description is now as follows:
Parameters:
List of BYTES Data to be copied to the heap
WORD Number of bytes to copy
WORD Link to next element in heap chain
Result:
WORD Heap address where the data was stored
Description:
Pops the data bytes off the stack and stores them on the
heap. Stores the forward link in the link field of the in-
ternal heap control block. Returns the address in the heap
of the stored data. These data must subsequently be accessed
with absolute memory addressing (level 255, see LOAD).
Page 116:
"This exception is emitted by..." should be "This instruction
is emitted by...".
Page 157:
The CVABS A-code is incorrectly documented. The correct text
follows:
Parameters:
WORD Absolute address of data on stack
Result:
BYTE -1 (absolute level indicator)
WORD Absolute address of data
Description:
CVABS reads a 16-bit absolute address off the stack, pushes
an absolute level indicator byte (-1) on the stack, and then
re-pushes the address. In effect, the instruction inserts a
-1 byte in the stack just before the top word. This is used
to quickly prepare a pointer value for use in a LOAD or STORE
instruction.
Page 186:
In the example about the use of address representation
clauses, a typo in the PC's screen memory address causes it
to be incorrectly listed as 16#8000#:0000. As seasoned hack-
ers know, the address is actually 16#B000#:0000. That's a
letter B instead of a digit 8.
Unfortunately, this is really a moot point, since address
representation clauses as detailed here are not implemented
in release 1.25.
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