Black Box 4/BlackBox.cdr/dosutils/xeq140.arj/XEQ.DOC

Text File | 1992-02-01 | 14.6 KB | 339 lines

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                   XEQ
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       XEQ - COM File Library and Command Executor

This program allows COM files to be stored inside XEQ's code and executed
by the command:
    XEQ command
For example, if BEEP.COM has been added to XEQ then:
    XEQ BEEP
will execute the BEEP program stored inside XEQ. The original BEEP.COM
can be removed from the hard disk (onto a backup floppy!!!). If the
specified command is not in XEQ it is passed to the DOS for execution as
if directly typed at the DOS prompt.

PURPOSE
    The purpose is to prevent wasted hard-disk space by those pesky
little COM files we don't seem to be able to do without. When hard disks
are formatted they are given an allocation size (called a cluster size)
and this is typically 2048 or 4096 bytes. So when you save a 7 byte
COM file like BEEP.COM, it takes up a full cluster. By combining these
COM files into this program or LIBRARY, several COM files can be stored
in one file (the XEQ program itself) and still be accessed without this waste
in hard disk space.

In order to make the body of XEQ as small as possible, only a limited
number of options are available. They are

    XEQ [/R]<command> Execute <command> if it is in the library
                or passes it to DOS for execution if not
    XEQ /A<command>   Add <command>.COM to library if not existent
    XEQ /D<command>   Delete command from library if existent
    XEQ /E<command>   Extract command from library to .COM file if existent
    XEQ /L          List the <commands> in the library
    XEQ /H          Display HELP information
    XEQ           Attempt to run internal AUTOXEQ.COM, else HELP
    XEQ /P<parms>      As above but passed <parms> to AUTOXEQ.COM
    XEQ /C<command>      Suppress the reprocessing of the command line
    XEQ /F          Freeze library

COMMAND DETAILS

/R - run a command

If no switch is given, the /R is assumed. If the given command name
is in the library it is executed directly from there. XEQ internally
relocates the stored file in memory so that the memory image is
identical to the image if it had been loaded from the COM file on
disk. This includes the way DOS loaded a COM file and the pretests
for argument suitability and register set up. Thus ALL COM files
should execute normally when run from within XEQ.

If the command is not found in XEQ then the string is passed to a DOS
shell for execution. A second copy of COMMAND.COM is spawned with the
command added after the /C switch. Therefore the command can be an
internal, external, batch, EXE or COM file. (NOTE: SEE TSR LIMITATION
BELOW.)

/A - add a command

Adds a COM file to the XEQ library. The filename given must either
have no extension or .COM and the name part can contain standard DOS
wildcards. A drive and/or path may be given to the target file.
If the file is already in the library it will not be added. A warning
message is given in this eventuality. Similarly if there is
insufficient room to add a file, the addition of this file will be
skipped with a warning. When wildcards exist, XEQ will attempt to add
all files even if a given file cannot be found or is too big. Any attempt
to add the current XEQ.COM file to itself (even if renamed under
DOS3.x) will be prevented. (In DOS 2.x this safety feature can be
thwarted by renaming XEQ.COM. A file called XEQ.COM is the only one
excluded from being added.)

/D - delete a command

Removes the named command from the library. The filename given must either
have no extension or .COM and the name part can contain standard DOS
wildcards. A prompt asks for confirmation of the delete. 'Y' will
delete the command, 'N' will skip deleting the command, 'G' will GO
and delete this command and all further matching ones without asking
again and 'A' will abort the entire delete process. Obviously 'G' is final
and cannot be aborted once selected. Abort will cancel the effect of
any 'Y' answers previously, AND NO COMMANDS WILL HAVE BEEN DELETED.

/E - extract a COM file

When the /E switch is used to extract a COM file, a full path for the
resulting file may be specified. If the file already exists at that location,
extraction does not occur. The filename given must either
have no extension or .COM and the name part can contain standard DOS
wildcards. The extracted file has the same date stamp as the COM file it was
originally stored from. The file is NOT deleted from the library.

/L - list the library files

Displays a list of all files stored in XEQ. The original time and
date stamp are displayed along with the file's byte size. At the end
of the list the remaining space in XEQ is displayed, along with an
indication of how much space has been saved by using XEQ (and
deleting the original COM files). This computation is based upon
the following:

DOS 2.x
The value is the difference between the total clusters used by
XEQ.COM on the default drive and the sum of all the clusters which
would have been used on the default drive if each command was in its
own COM file.
The results can be misleading if say, you run XEQ/L while
the drive default points to a floppy with a cluster size of 1024, but
the DOS path executed XEQ.COM from the harddisk with a different
cluster size. In this case the savings indicated are the bytes saved
IF XEQ.COM WAS LOCATED ON THE DEFAULT DRIVE.

DOS 3.x
The value is as above, but uses the cluster size of the drive it
found XEQ.COM on and assumes that the COM files would have been on
that drive if they were in separate files.
Under DOS 3.x the savings always relate to the drive the path found
XEQ.COM on and is independent of the default drive cluster size.

/H - Display the help screen

NO ARGUMENTS
XEQ will try to find internal command AUTOXEQ.COM and if found will
execute it. This can be any COM file so named. Arguments can be supplied
using the /P command. If no such internal file exists, then HELP is
displayed.

This feature can make XEQ perform a certain action if no arguments
are supplied to it.

/P Run AUTOXEQ with parameters
This performs as with NO ARGUMENTS above, but also passes the given
parameters to the AUTOXEQ internal program. For example, if LIST.COM
was stored in XEQ.COM as AUTOXEQ, then XEQ /PXEQ.DOC will start
LIST.COM and pass it the file name XEQ.DOC.

/C Run the command but do not reprocess the command line
Normally when XEQ is run without the /C switch, both the command line
is reprocessed and the final program name is inserted for PMAP etc.
(see below). When the /C switch is present, the original command line
from the DOS prompt is passed to the final program and the program
name returned by the program as argument 0 is the original XEQ name.
For example:

If the DOS line is:

C> XEQ pgm arg1

then <pgm> sees only 1 argument <arg1> and the internally stored
program name is <pgm>. If <pgm> was in C, argv[0] = pgm and argv[1] =
arg1.

If the DOS line is:

C> XEQ /C pgm arg1

then <pgm> sees 3 arguments </C> <pgm> and <arg1> and the internally
stored program name is <XEQ>. If <pgm> was in C, argv[0]=XEQ,
argv[1]=/C, argv[2]=pgm and argv[3]=arg1.

The primary purpose of the /C switch is to allow programs resident in
XEQ to ascertain where they originally came from, when this is desirable.

Note that is not possible to use the /C in conjunction with the
AUTOXEQ function unless AUTOXEQ is specifically called out on the
command line.

/F Freeze the library.  If you enter this switch and then answer Y,
the library file will be frozen. This means ALL commands are
inoperative except the /R or implied /R.  This prevents, among other
things, an end-user of the library from seeing or changing its
contents. A frozen library cannot be readily unfrozen.  In an
emergency you can use a BINARY file editor (or DEBUG/SYMDEB) to
change a single BYTE as follows:

    VERSION            OFFSET        OLD    NEW
      1.40             05BFH         1     8

WARNING! This is version specific data.

LIMITATIONS

    As a COM file can only be 64K long, COM files cannot
be added to XEQ if this figure would be violated, as XEQ is a COM file
itself. The /L command indicates the amount of space left and any
attempt to add a file which would exceed the 64k limit is prevented. Any
number of COM files can be added until this number is reached.
        When a command is added or deleted from XEQ, a new copy of XEQ must
be rewritten to disk. How it is written back depends on the version of DOS
you are running.

DOS 2.x users

The revised library is always written to the current drive and directory as
XEQ.COM, regardless of where the original copy of XEQ was found
(it may have been loaded from elsewhere because of DOS's path
capability). Therefore to update the original copy of XEQ, the /D or /A
commands should be performed in the drive and directory of the
original. If not, then the original copy of XEQ will still exist in its
original location and the updated version in the current drive and
directory. The new version of XEQ will always be called XEQ.COM, regardless
of whether the original program was called XEQ.COM or not.

DOS3.x users

The revised library will be written over the original using the original's
name. Thus doing a proper update of the original. The library can be given
any name and this will be retained during the updating.

MULTIPLE LIBRARIES

For DOS 2.x user it is recommended that only one library XEQ.COM exist on the
system. As adding or deleting from a renamed library file results in
the new copy being called XEQ.COM on the current drive, care would
have to be taken to prevent the overwriting of a legitimate XEQ.COM,
and the new XEQ.COM would have to be renamed to the original name of
the revised library.

For DOS 3.x users multiple libraries are more feasible as the updated library
is always the original file no matter what it was called or where it
was located. Thus maintaining multiple libraries is much simpler. CED
(see below) can be used to avoid the need to remember which library
contains a given command.

TERMINATE & STAY RESIDENT PROGRAMS

TSR programs can be stored inside XEQ and will install just like the
original program. HOWEVER, NEVER RUN A TSR PROGRAM THROUGH XEQ WHICH
IS NOT STORED IN XEQ. When XEQ cannot find a program it passes the name to
DOS to run in a shell. If this program is a TSR it will freeze more
memory than needed. XEQ has no way of knowing if a program it is
about to execute externally is a TSR.

Beginning with version 1.10, XEQ will put the name of the file being
run into the space between the end of the environment table and the
start of the program. This is where DOS 3.x puts the running program
name and XEQ will only duplicate this when running under DOS3.x. The
purpose of this is to allow the running program to know its own name
and to let TSR memory map programs like MAP.COM and MAPMEM.COM show
the real program name which is resident.

A limitation exists for this however. The name stored is of the form
d:\path\filename.COM. The space available to store this string cannot
be increased and is set by the original running of XEQ. So if XEQ is
the name of the comm library, the name of the actual program stored
can only use the first 3 letters, truncating the full name. If this
is important to you, the solution is to rename the library to a
filename of 8 letters.  This will ensure sufficient space for any
revision to any other name.  Starting with version 1.3 this is the
mode of operation. Earlier versions destroyed the path information
and this gave trouble to programs expecting to be able to recover the
full drive, path and name information from argv[0] (in C) or %0 (in
compiled batch files).

Starting with version 1.30, the final program name is also correctly
set for such memory mapping programs as PMAP.

USAGE TIP

The CED utility and its synonym feature can make the use of XEQ
transparent in use. For example, if BEEP.COM is stored inside XEQ then a
synonym like
    SYN BEEP XEQ BEEP
will cause BEEP to be run out of the XEQ file just by entering BEEP.

DISCLAIMER

    Hardwood Software Associates guarantees XEQ.COM will do NOTHING
useful at all. You use it at your own risk (make backups of the COM files
stored within XEQ before deleting them from your hard disk). However, it
seems to perform as described here and may be of use to you.

    Colin J. Stearman [71036,256]
    Senior Associate
    HS Associates
    143 Ash Street
    Hopkinton, MA 01748

======================================================================
            EDIT LOG
    REV    DATE        NAME        DETAIL
    1.01    14-MAR-87    C.STEARMAN    Fixed bug if COM file name
                        is one character
    1.02    27-MAR-87       C.STEARMAN    Aligned file size column
                        Added disk bytes saved calc
    1.03    1-APR-87        C.STEARMAN      Fixed bug if in list if file
                        was longer than 9999 bytes.
                        Fixed error in saved space
                        computation
    1.10    2-APR-87    C.STEARMAN    Under DOS 3.x updating writes
                        to original file. Also updates
                        command name in environment
                        for MAP, added wildcard,
                        fixed yet another space
                        computation bug, used local
                        stack for external run only
    1.11   13-APR-87        C.STEARMAN    Revised space saved compute,
                        see note above
    1.12   16-APR-87        C.STEARMAN      Fixed bug in load_run module
                        which did not initialize stack
                        correctly. Bug manifested it-
                        self when MODE was run
                        internally. Returned bad
                        parameters message
        1.13   22-APR-87       C.STEARMAN       Fixed wrong message of file
                        not found in /A
                        Improved construction of PSP
                        when running internals. May
                        clean up some compatability
                        problems. Fixed drive validity
                        test. If wild cards in argu-
                        ments, did not set AX correct-
                        ly per DOS loaded.
    1.14  29-APR-87       C.STEARMAN        Fixed bug when executing ext-
                        ernal commands. Local stack
                        trashed passed command string.
                        Also stack crash caused by
                        allowing XEQ.COM to grow to
                        large. Caused random crashes.
                        Added confirm delete
    1.15 30-MAY-87          C.STEARMAN    Cleaned up help screen and
                        identified which library file
                        was accessed. Fixed bug in
                        extract where a 1 character
                        filename did not have .COM
                        added to it.
    1.20 15-MAR-91          C.STEARMAN    Added /H and the search for
                        internal command AUTOXEQ.COM
    1.21 24-MAR-91          C.STEARMAN    Added /P for parameters to
                        AUTOXEQ.COM
    1.30 24-APR-91          C.STEARMAN    Modified storage method for
                        program name to include path,
                        added program name for PMAP
    1.31 24-APR-91          C.STEARMAN    Added the /C switch
    1.40 01-FEB-92          C.STEARMAN    Added /F switch
======================================================================
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