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Notes on the MS-DOS Perl port
Diomidis Spinellis
(dds@cc.ic.ac.uk)
[0. First copy the files in the msdos directory into the parent
directory--law]
1. Compiling.
Perl has been compiled under MS-DOS using the Microsoft
C compiler version 5.1. Before compiling install dir.h as
<sys/dir.h>. You will need a Unix-like make program (e.g.
pdmake) and something like yacc (e.g. bison). You could get
away by running yacc and dry running make on a Unix host,
but I haven't tried it. Compilation takes 12 minutes on a
20MHz 386 machine (together with formating the manual), so
you will probably need something to do in the meantime. The
executable is 272k and the top level directory needs 1M for
sources and about the same ammount for the object code and
the executables.
The makefile will compile glob for you which you will
need to place somewhere in your path so that perl globbing
will work correctly. I have not tried all the tests or the
examples, nor the awk and sed to Perl translators. You are
on your own with them. In the eg directory I have included
an example program that uses ioctl to display the charac-
teristics of the storage devices of the system.
2. Using MS-DOS Perl
The MS-DOS version of perl has most of the functional-
ity of the Unix version. Functions that can not be provided
under MS-DOS like sockets, password and host database
access, fork and wait have been ommited and will terminate
with a fatal error. Care has been taken to implement the
rest. In particular directory access, redirection (includ-
ing pipes, but excluding the pipe function), system, ioctl
and sleep have been provided.
[Files currently can be edited in-place provided you are cre-
ating a backup. However, if the backup coincidentally has
the same name as the original, or if the resulting backup
filename is invalid, then the file will probably be trashed.
For example, don't do
perl -i~ script makefile
perl -i.bak script file.dat
because (1) MS-DOS treats "makefile~" and "makefile" as the
same filename, and (2) "file.dat.bak" is an invalid filename.
The files "makefile" and "file.dat" will probably be lost
forever. Moral of the story: Don't use in-place editing
under MS-DOS. --rjc]
2.1. Interface to the MS-DOS ioctl system call.
The function code of the ioctl function (the second
argument) is encoded as follows:
- The lowest nibble of the function code goes to AL.
- The two middle nibbles go to CL.
- The high nibble goes to CH.
The return code is -1 in the case of an error and if
successful:
- for functions AL = 00, 09, 0a the value of the register DX
- for functions AL = 02 - 08, 0e the value of the register AX
- for functions AL = 01, 0b - 0f the number 0.
See the perl manual for instruction on how to distin-
guish between the return value and the success of ioctl.
Some ioctl functions need a number as the first argu-
ment. Provided that no other files have been opened the
number can be obtained if ioctl is called with
@fdnum[number] as the first argument after executing the
following code:
@fdnum = ("STDIN", "STDOUT", "STDERR");
$maxdrives = 15;
for ($i = 3; $i < $maxdrives; $i++) {
open("FD$i", "nul");
@fdnum[$i - 1] = "FD$i";
}
2.2. Binary file access
Files are opened in text mode by default. This means
that CR LF pairs are translated to LF. If binary access is
needed the `binary' function should be used. There is
currently no way to reverse the effect of the binary func-
tion. If that is needed close and reopen the file.
2.3. Interpreter startup.
The effect of the Unix #!/bin/perl interpreter startup
can be obtained under MS-DOS by giving the script a .bat
extension and using the following lines on its begining:
@REM=("
@perl %0.bat %1 %2 %3 %4 %5 %6 %7 %8 %9
@end ") if 0 ;
(Note that you will probably want an absolute path name in
front of %0.bat).
March 1990
Diomidis Spinellis <dds@cc.ic.ac.uk>
Myrsinis 1
GR-145 62 Kifissia
Greece
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