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ProgManual
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1991-11-20
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AmigaDOS Replacement Project V1.1 (REL2)
AmigaDOS Replacement
Project V1.1 (REL2)
ABSTRACT
An overview of the new functions and support materials
available to programmers using ARP, including a discussion
of calling arp.library from the C language.
CONTENTS
Current Status of ARP................................ 1
1. Changes to old functions............................. 1
1.1 GADS().......................................... 1
1.2 FileRequest()................................... 1
2. New Functions........................................ 2
2.1 Process Control and Resident.................... 2
2.2 Date functions.................................. 3
2.3 Misc functions.................................. 3
3. Language Support..................................... 3
3.1 C Language Support.............................. 4
3.2 Modula II support............................... 7
- i -
ARP Prog Manual V1.1 Software (REL2) February 27, 1988
Current Status of ARP
This release meets our first goal in producing ARP. It is
now possible for users of the Amiga to work in a practically
BCPL free environment, allowing programmers to write
software free of BCPL headaches. This release of the
library (arp.library) introduces what we feel are important
advances and standards for the Amiga, including new process
control functions and a resident program standard. Old
functions have been enhanced, the GADS() argument parser now
supports a new template type which allows the user to enter
any number of arguments, and the FileRequest() has been very
greatly enhanced, it now sports a parent gadget, and
provides much more programmer control than previously. It is
beautiful.
1.
Changes to old functions
Only GADS() and FileRequest() received significant
enhancements. Both of these are completely compatible with
older code.
1.1
GADS()
The only change to GADS() is the introduction of a new
template type which allows any number of arguments to be
placed on the command line. It consists of the usual slash
followed by three periods (/...). On return from GADS(),
the array element which corresponds to the multiarged type
will be a pointer to another array of character pointers (
*(**char)) which contain the actual arguments entered by the
user. This array is guranteed to be null terminated. See
the GADS manual page for more information. Note that the
ugly and limited ",,,," construct is still supported if you
are into commas.
1.2
FileRequest()
FileRequest has been greatly enhanced and extended in this
release. You can now alter FileRequest's window, add or
subtract your own gadgets, handle gadget events relating to
your own gadgets, and so on. The FileRequester structure
has been changed, however old code using the old
FileRequester structure will still work as long as you set
the old fr_Flags variable to zero as warned. See the
FileRequest() manual page and arpbase.[ih] for more
information.
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
2.
New Functions
Many new functions have been added in this release. Perhaps
the most important are the process control functions and the
date functions. The date functions support international
date formats for both input and output, and were provided by
Ken Salmon.
2.1
Process Control and Resident
arp.library now has a background process spawner which
should eliminate any future need for programs to call
Execute(). You can set many options with this function
including stdio handles, or you can specify a flag which
will create a new interactive environment for the process.
Note that this function creates new CLI style processes as
its default action, and it may be called from Workbench
programs. It also searches the Resident list first, and so
may be used to run multiple copies of the same code, and it
automatically takes advantage of stack settings using the
new ResidentProgramTag.
The spawner will not execute BCPL programs. This would
have been done if it were reasonably possible to do so, but
it was not. However, now that most of the ARP command
replacements are done this should not be an issue, since any
disk which has arp.library will also have the command
replacements. The spawner will return an error code to you,
at which point you can inform the user, or attempt to
execute the BCPL program using Execute(), and all its
attendent problems.
The spawner causes processes to automatically clean up
after themselves, this includes closing all stdio handles
and freeing stack and possibly also data memory, if that was
allocated by the startup code, so there is no reason for
your program to hang around waiting for child exits,
although you can if you wish to. For more information, see
the ASyncRun() manual page.
2.1.1
Resident programs
This release introduces a method
for creating shared text processes on the Amiga. The code
for these processes in the past has had to be reentrant, and
that is still the simplest case. ARP provides a method for
specifying that a separate data segment should be allocated
if your program is resident, and you can then copy the data
to the new data segment, and use that, thus preserving a
clean slate for the next execution. The compiler startup
code is responsible for initializing the data segment. This
was done to keep the support routines as general as
possible, the actual data copying is extremely short, as a
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
look at the arprescrt0.s source will demonstrate.
Users now have a program to install processes as
Resident as well as a program to execute these processes.
Hopefully more people will take advantage of the new
resident standard and write more of this low overhead
software. For more informtion, see the manual page for
Resident in the users manual, and the AddResidentPrg() and
LoadPrg() etc., functions in the programmers manual.
2.2
Date functions
These date functions provide a method for converting between
AmigaDOS datestamps and strings and vice-versa. These
functions provide a wide variety of international date
format input and output conversions. You must specify the
conversion you want. The ARP standard has been to accept
the value of the dateformat environment variable as set by
users. If this is undefined, default to the current AmigaDOS
convention. You must check this variable yourself, the
StrtoStamp() and StamptoStr() functions will not do this for
you. For more information see the manual pages for these
two functions, as well as the DateTime struct in
arpbase.[ih].
2.3
Misc functions
The following utility functions have been added in V34:
- PreParse() - prepare a string for PatternMatch()
- LMult(), LDiv(), LMod() - LONG multiply divide and
modulus routines.
- TackON() - add a filename to a pathname.
- BaseName() - return a pointer to the BaseName of a
PathName.
3.
Language Support
Support is provided in the form of header files and linkable
libraries or pragma files for Aztec C, Lattice C TDI Modula
II, and of course assembler.
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
3.1
C Language Support
Startup code which automatically opens arp.library and
initializes IntuitionBase and GfxBase as well as ArpBase is
provided for both Lattice and Manx. We have attempted to
keep filename conventions and header file proliferations to
a minimum, and have succeeded pretty well so far, so the
discussion which follows applies pretty well to both
compilers. Differences are noted where they are
significant. The general goals have been to minimize the
overall impact on the compiler user, and to make the code we
supply assemble/compile with the usual tools provided by
each manufacturer. So, for example, the Manx code still
uses the two functions cli_parse() and wb_parse() to do
pretty much the same things as they did before, while
Lattice code remains in _main(). Each compilers workbench
interface is unchanged, and the normal default CLI command
line processing should appear the same or very similar.
The differences are mostly in the use of GADS() to do
CLI parsing, and in the use of the ARP tracking functions to
allocate memory, although we also provide some resident
support code that provides very extended capabilities.
3.1.1
How to linkup with ARP
The easiest way to link up
with arp is to use the arp 'wrapper' which we supply for
both Lattice and Manx compilers. This code opens
arp.library, and initializes GfxBase and IntuitionBase as
valid pointers from the values in ArpBase. To use this ARP
wrapper, simply link with arp.lib (Lattice users should also
use the arpc.o instead of the usual c.o as the first module
in their blink command lines), and then with your compiler
libraries. Here are sample link lines for Manx and Lattice:
ln program.o -larp -lc
blink arpc.o prog.o to prog lib arp.lib lc.lib amiga.lib
If you prefer to use the OpenLibrary() call, then instead of
the above command lines, simply include the library file
a.lib in your usual link command line.
3.1.2
GADS
The use of GADS() to handle the program
arguments from the CLI command line introduces some
differences. argc will be the number of arguments actually
entered, and argv[0] will be the program name, as usual, but
the actual arguments may or may not be in successive array
positions in argv, and the actual element in the argv array
may be a boolean value (if a /S was used), a pointer to
character (as usual) or itself the base of another argv
style array (if the new /... template type is used). (The
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
default template, which consists simply of a series of
commas, does provide for standard C processing of command
line arguments.)
To supply your own template, set the global variable
CLI_Template to point to the string containing your
template. You can provide an extended help message by
setting the global variable CLI_Help to what you wish to
display if the user asks for more help:
char *CLI_Template = "FROM/A,TO,OPT/K";
char *CLI_Help = "This is an extra help string";
See the GADS manual page and some of the short example
programs in the demos directory. Note that you will not get
error returns from GADS() using the default startup code,
the startup code handles those on its own, displaying the
GADS() error message and aborting the program.
3.1.3
Exiting under ARP
It is *not* recommended that you
call the ArpExit() function from C, this could possibly
bypass allocations that your compiler library has made on
your behalf, and cause problems with open files or
unreleased memory. The recommended way to exit from a
program using ARP, whether or not you are using the supplied
startup code, is to use exit() or to simply fall off the end
of the world. If you are not using the arp startup code you
should first CloseLibrary(ArpBase), if you are using the arp
startup code you should not CloseLibrary(ArpBase).
3.1.4
Availabilty of source
All the source code to the
startup code is provided, so you can see exactly what it
does and modify it should you need to. In each case it was
assembled using the native tools supplied by the
manufacturer.
3.1.5
Creating shared text (resident) programs in C
At the
time this is written we still have not been able to
succesfully assemble resident startup code for Lattice.
This appears to be a limitation of the lattice supplied asm.
The lattice compiler is very capable of taking advantage of
this, and lattice has been very helpful, but we still do not
have the support for resident code and Lattice.
Manx users can take advantage of the shared code and
stack setting capabilities of the resident code standard as
follows.
- 1) Use the +b option to the C compiler for all the
modules in the program.
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
- 2) You must use the rstart.o or rstart32.o as the first
module in your linker command line, and you should also
link with res.lib or res32.lib.
The default stack has been set to 10240 for the rstart
modules. If this is too high or too low, you can change the
arprescrt0.s file and reassemble. Manx has promised support
for the ARP resident standard with their 4.0 release, but
currently the only way to set the stack is to reassemble.
3.1.5.1
Programming using Resident
You do not have to
write re-entrant code using the ARP resident standard.
arp.library and the startup code cooperate to make copies of
your data and bss segments, so you may feel free to alter
static global data without being concerned about not being
able to be resident. The only problems that you are likely
to have involve pre-compiled references from data to data,
and only if these are not read-only.
As an example, consider the following:
BYTE buffer1[100];
BYTE buffer2[100];
struct b {
BYTE *b1, *b2;
};
struct b example = {
&buffer[0],
&buffer[1]
};
In the above example, the references to buffer[0] and
buffer[1] in struct b are a reference from data (the struct
b data) back to other data (the buffer data). When these
data references are cloned by the resident startup code,
they will still refer to the same memory location, they are
not relocated. That means that any writes to buffer[0] or
buffer[1] using the addresses stored in the structure will
change the original copy of the data, and therefore result
in a checksum error being reported the next time the
resident program is run.
The solution to this is to perform run-time
initialization of data such as this. Note that this applies
only to data that is going to be written. Data which is not
altered is data you don't have to worry about at all. The
most likely candidates for run-time initialization in Amiga
programs are MenuItem structures and Menu structures. I
have my own version of the MicroEmacs that has been floating
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ARP Prog Manual V1.1 Software (REL2) February 27, 1988
around which uses Amiga windows and menus, and is not at all
careful about altering static data. I converted this to run
resident using only four loops (one for each menu) in about
a half an hour. Now each invocation of the Editor uses only
4000 bytes of stack (instead of the 20000 I use at the CLI),
and it uses no more memory for its code, either in a ramdisk
or in memory. Since the actual program is 35,644 bytes, I
save about 50,000 bytes each time the program is invoked.
Not bad for a half an hours work.
You can tell if you are running as a resident launched
program if you examine the global long __fromdisk__. This
variable will be non-zero (-1) when you are not resident.
3.2
Modula II support
We have not yet received a Modula II support package from
anyone. No one directly involved with ARP speaks Modula II,
so we are dependent on contributors for support for this
language. The MII support materials we do provide are from
the first release, and cover only the first release
functions. These were contributed by Martin Taillefer.
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