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                 Version 8.5 of Icon for MS-DOS

                        Ralph E. Griswold
    Department of Computer Science, The University of Arizona



1.__Introduction

   Version 8.5 of Icon for MS-DOS should run on any computer run-
ning MS-DOS 3.0 or higher.  Math co-processors are supported and
used if present; otherwise software emulation is used.  Approxi-
mate 500K of free RAM is needed to run Icon satisfactorily.  Two
versions of Icon's executor system are provided. One supports
arithmetic on integers of unlimited magnitude and the other does
not. The latter is considerably smaller than the former and can
be used if you do not have enough RAM for the former.

   Version 8.5 of Icon for MS-DOS is distributed on 5.25" or 3.5"
diskettes, which include executable binary files, a few test pro-
grams, and documentation in machine-readable form. Printed docu-
mentation is included with diskettes distributed by the Icon Pro-
ject at The University of Arizona.

   This implementation of Icon is in the public domain and may be
copied and used without restriction.  The Icon Project makes no
warranties of any kind as to the correctness of this material or
its suitability for any application.  The responsibility for the
use of Icon lies entirely with the user.


2.__Documentation

   The basic reference for Version 8 of Icon is the second edi-
tion of the bok The Icon Programming Language [1].  This book is
available from the Icon Project at The University of Arizona. It
also can be ordered through any bookstore that handles special
orders.

   The new features of Version 8.5 of Icon are in an accompanying
technical report [2].


3.__Installing_MS-DOS_Icon

   Two executable binary files are needed to run Icon:

        icont.exe   translator
        iconx.exe   executor

These files should be located at a place on your PATH specifica-
tion.  As mentioned in Section 1, there are two forms of iconx:
one without large-integer arithmetic and one with it.  The former
is named iconx.exe as distributed, while the latter is named



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iconxl.exe.

   The distribution is contained in several files in LZH format.
A copy of lharc.exe is included for dearchiving. The distribution
files are:

        lharc.exe    dearchiving utility
        icon.lzh     executable binary files [531KB]
        samples.lzh  Icon programs and data [3KB]
        docs.lzh     documents [55KB]
        readme       installation overview and recent notes

The figures in brackets give the approximate amount of disk space
needed when the files are extracted from their archives. (It is
not necessary to keep both executors.)

   To install the .exe files, set your current directory to the
desired place, place the appropriate distribution diskette in
drive A, and dearchive the files there using lharc.exe.

        a:lharc a:icon.lzh

The same technique can be used for extracting the remaining
files.

   The simplest way to use Icon is to pick the executor that fits
your needs, place it at a location on your path, and rename it to
iconx.exe if necessary. For example, if you want the executor
that supports large-integer arithmetic, the following will do:

        rename iconxl.exe iconx.exe

However, if you want to use both executors, you can either name
them differently (such as they are named above) and use them by
their different names, or you can name them the same but put them
in different locations. In this case, you will have to change
your path depending on which one you use.


4.__Running_MS-DOS_Icon_-_Basic_Information

   Files containing Icon programs must have the extension .icn.
Such files should be plain text files (without line numbers or
other extraneous information).  The icont  translator produces an
``icode'' file that can be executed by iconx.  For example, an
Icon program in the file prog.icn is translated by

        icont prog.icn

The result is an icode file with the name prog.icx.  This file
can be run by

        iconx prog.icx




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If your executor is named differently, simply use that name. For
example, if your executor is named iconxl.exe, use

        iconxl prog.icx

Alternatively, icont can be instructed to execute the icode file
after translation by appending a -x to the command line, as in

        icont prog.icn -x

This only works if your executor is named iconx.exe, since the -x
option looks for this name.  In the sections that follow, it is
assumed that the executor is named iconx.exe.

   If icont is run with the -x option, the file prog.icx is left
and can be run subsequently using an explicitly named executor as
described above.

   The extensions .icn and .icx are optional. For example, it is
sufficient to use

        icont prog

and

        iconx prog


   iconx will find an icode file if it is in the current direc-
tory or at place given on your PATH specification.


5.__Testing_the_Installation

   There are a few programs on the distribution diskette that can
be used for testing the installation and getting a feel for run-
ning Icon:

     hello.icn   This program prints the Icon version number,
                 time, and date. Run this test as

                         icont hello
                         iconx hello

                 Note that this can be done in one step with

                         icont hello -x


     cross.icn   This program prints all the ways that two words
                 intersect in a common character. The file
                 cross.dat contains typical data. Run this test
                 as




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                         icont cross -x <cross.dat


     meander.icn This program prints the ``meandering strings''
                 that contain all subsequences of a specified
                 length from a given set of characters. Run this
                 test as

                         icont meander -x <meander.dat


     roman.icn   This program converts Arabic numerals to Roman
                 numerals. Run this test as

                         icont roman -x

                 and provide some Arabic numbers from your con-
                 sole.

If these tests work, your installation is probably correct and
you should have a running version of Icon.


6.__More_on_Running_Icon

   For simple applications, the instructions for running Icon
given in Section 4 may be adequate. The icont translator supports
a variety of options that may be useful in special situations.
There also are several aspects of execution that can be con-
trolled with environment variables.  These are listed here. If
you are new to Icon, you may wish to skip this section on the
first reading but come back to it if you find the need for more
control over the translation and execution of Icon programs.

6.1__Arguments

   Arguments can be passed to the Icon program by appending them
to the command line.  Such arguments are passed to the main pro-
cedure as a list of strings.  For example,

        iconx prog text.dat log.dat

runs the icode file prog.icx, passing its main procedure a list
of two strings, "text.dat" and "log.dat".  The program also can
be translated and run with these arguments with a single command
line by putting the arguments after the -x:

        icont prog -x text.dat log.dat

These arguments might be the names of files that prog.icn reads
from and writes to. For example, the main procedure might begin
as follows:





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        procedure main(a)
           in := open(a[1]) | stop("cannot open input file")
           out := open(a[2],"w") | stop("cannot open output file")
                       .
                       .
                       .

See also the information about the processing of command-line
arguments given in Section 6.4.

6.2__The_Translator

   The icont translator can accept several Icon source files at
one time.  When several files are given, they are translated and
combined into a single icode file whose name is derived from the
name of the first file.  For example,

        icont prog1 prog2

translates the files prog1.icn and prog2.icn and produces one
icode file, prog1.icx.

   A name other than the default one for the icode file produced
by MiconfR can be specified by using the -o option, followed by
the desired name. For example,

        icont -o probe.icx prog

produces the icode file named probe.icx rather than prog.icx.

   If the -c option is given to icont, the translator stops
before producing an icode file and intermediate ``ucode'' files
with the extensions .u1 and .u2 are left for future use (normally
they are deleted).  For example,

        icont -c prog1

leaves prog1.u1 and prog1.u2, instead of producing prog1.icx.
These ucode files can be used in a subsequent icont command by
using the .u1 name. This saves translation time when the program
is used again.  For example,

        icont prog2 prog1.u1

translates prog2.icn and combines the result with the ucode files
from a previous translation of prog1.icn. Note that only the .u1
name is given. The extension can be abbreviated to .u, as in

        icont prog2 prog1.u

Ucode files also can be added to a program using the link
declaration.

   Icon source programs may be read from standard input.  The



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argument - signifies the use of standard input as a source file.
In this case, the ucode files are named stdin.u1 and stdin.u2 and
the icode file is named stdin.icx.

   The informative messages from the translator can be suppressed
by using the -s option.  Normally, both informative messages and
error messages are sent to standard error output.

   The -t option causes &trace to have an initial value of -1
when the icode file is executed.  Normally, &trace has an initial
value of 0.

   The option -u causes warning messages to be issued for unde-
clared identifiers in the program.

   Icon has several tables related to the translation of pro-
grams.  These tables are large enough for most programs, but
translation is terminated with an error message, indicating the
offending table, if there is not enough room.  If this happens,
larger table sizes can be specified by using the -S option. This
option has the form -S[cfgilnrstCFL]n, where the letter following
the S specifies the table and n is the number of storage units to
allocate for it.

     c  constant table          100
     f  field table             100
     g  global symbol table     200
     i  identifier table        500
     l  local symbol table      100
     n  line number table      1000
     r  record table            100
     s  string space          20000
     t  tree space            15000
     C  code buffer           15000
     F  file names               10
     L  labels                  500

The units depend on the table involved, but the default values
can be used as guides for appropriate settings of -S options
without knowing the units.  For example,

        icont -Sc200 -Sg600 prog

translates prog.icn with twice the constant table space and three
times the global symbol table space that ordinarily would be pro-
vided.

6.3__Environment_Variables

   When an icode file is executed, several environment variables
are examined to determine execution parameters.  The values
assigned to these variables should be numbers.

   Environment variables are particularly useful in adjusting



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Icon's storage requirements.  Particular care should be taken
when changing default values: unreasonable values may cause Icon
to malfunction.

   The following environment variables can be set to adjust
Icon's execution parameters. Their default values are listed in
parentheses after the environment variable name:

        TRACE (undefined).  This variable initializes the value
     of &trace.  If this variable has a value, it overrides the
     translation-time -t option.

        NOERRBUF (undefined).  If this variable is set, &errout
     is not buffered.

        STRSIZE (65000). This variable determines the size, in
     bytes, of the region in which strings are stored.  If addi-
     tional string regions are needed, they may be smaller.

        BLKSIZE (65000).  This variable determines the size, in
     bytes, of the region in which Icon allocates lists, tables,
     and other objects.  If additional block regions are needed,
     they may be smaller.

        COEXPSIZE (2000). This variable determines the size, in
     32-bit words, of each co-expression block.

        MSTKSIZE (10000). This variable determines the size, in
     words, of the main interpreter stack.

        QLSIZE (5000). This variable determines the size, in
     bytes, of the region used by the garbage collector for
     pointers to strings.

   The maximum region size that can be specified is 65000.

6.4__Details_of_Command-Line_Processing

   The processing of command-line arguments normally is important
only in running iconx. Some details follow:

     +  An argument containing white space must be enclosed in
        double quotes.  For example, "abc def" is a valid argu-
        ment. The quotes are deleted in the string passed to
        iconx.

     +  If a quoted argument contains a double quote, the embed-
        ded quote must be preceded by a backslash. For example,
        "abc de\"f" is a valid argument. The outer quotes and the
        backslash are deleted in the string passed to iconx.

     +  If a non-quoted argument contains a double quote, the
        embedded quote can be preceded by a backslash or not. For
        example, abc\"d and abc"d are equivalent arguments.



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     +  To pass a lone double quote as an argument, precede it
        with a backslash.

     +  Wild-card characters are not expanded.

     +  Quote-balancing errors are not checked.  The start-up
        routine scans the residual command line from left to
        right.


7.__Features_of_MS-DOS_Icon

   MS-DOS Icon supports all the features of Version 8.5 of Icon,
with the following exceptions and additions:

     +  Pipes are not supported. A file cannot be opened with the
        "p" option.

     +  For files opened in the translate mode, the position pro-
        duced by seek() may not reflect the actual byte position
        because of the translation of carriage-return/line-feed
        sequences to line-feed characters.

     +  Path specifications can be entered using either a / or a
        \. Examples are:

                A:\ICON\TEST.ICN
                A:/ICON/TEST.ICN


     +  The following MS-DOS device names can be used as file
        names:

                console        CON
                printer        PRN LST LPT LPT1
                auxiliary port AUX COM RDR PUN
                null           NUL NULL

        For example,

                prompt := open("CON", "w")

        causes strings written to prompt to be displayed on the
        console.  Use of a null file name means no file is
        created.

     +  MS-DOS Icon also has some functions in addition to the
        standard repertoire.  These are described in the next
        section.








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8.__MS-DOS_Functions

   Disclaimer: The following functions provide a gateway to
facilities provided by MS-DOS and ROM BIOS. These functions
should be used with care, since Icon maintains strict control
over its environment (although it uses standard MS-DOS interfaces
and does not bypass MS-DOS or ROM BIOS in any way).  The descrip-
tions that follow are low-level descriptions. They assume
knowledge of the Intel 8086 (8088, 80x86) architecture.

Int86(L):

Int86(L) generates a hardware interrupt. The input is a list of
integer values: [interrupt number, ax, bx, cx, dx, si, di, es,
ds].  It returns a list of the form [flags, ax, bx, cx, dx, si,
di, es, ds].

   Great care must be taken in using this function. Some things
to watch out for are:

     +  Interrupt functions that alter the stack registers (SS or
        SP) or alter the MS-DOS memory chain (that is, allocate
        or deallocate memory in the MS-DOS memory region). When
        Icon expands memory, it expects the next allocation to be
        contiguous with the region it currently owns.

     +  Interrupt functions that operate on files opened by
        Icon's open(s) function - that is, closing, seeking,
        reading, or writing.

     +  The values of ES and DS may not be valid on return.


InPort(i):

InPort(i) returns an integer from hardware port i.

OutPort(i1,i2):

OutPort(i1,i2) writes value i2 to hardware port i1.

GetSpace(i):

GetSpace(i) allocates a static block of storage outside of Icon's
direct control (that is, it is not be affected by garbage collec-
tion).  This function simply calls the malloc() allocation rou-
tine and returns the address of the resulting block as a long
integer.

FreeSpace(A):

FreeSpace(A) frees a static block of storage, where A is a value
returned by GetSpace(i).  No check is make to verify that the
block was allocated by GetSpace(i). The results are unpredictable



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if it was not.  Arithmetic should not be performed directly on a
value returned by GetSpace(i).

Peek(A,i):

Peek(A,i) builds a string pointing to the address specified by A
with a length of i, where A is either an integer that specifies a
linear address value or a list of the form [segment, offset] and
i is a length (default 1).

   This is the only way of `seeing' the contents of a block of
storage allocated by GetSpace(i). Consider the following example:

        block := Peek(addr := GetSpace(100),100)

The value of block is a string of length 100 and addr is the
linear address of the block.

Peek(A,i) does not move data into Icon's memory region.  Instead,
it builds a string qualifier that points to the data.

Poke(A,s):

Poke(A,s) copies a string s to location A, where A is an address
specified in the same way as for Peek(A,s) and s is a string to
be copied to that storage location. The string is copied directly
into storage, byte by byte. No conversion is performed.  This is
the only way of assigning data to a block of storage allocated by
GetSpace(i).


9.__Known_Bugs

   A list of known bugs in Icon itself is given in [2].

   MS-DOS memory management also can cause problems.  Some pro-
grams that require a lot of memory may hang when run by the -x
option to icont.  This can be avoided by using iconx in a
separate step.  Also, if there is not enough free RAM, the sys-
tem() function may fail silently or hang.


10.__Reporting_Problems

   Problems with Icon should be noted on a trouble report form
(included with the distribution) and sent to











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        Icon Project
        Department of Computer Science
        Gould-Simpson Building
        The University of Arizona
        Tucson, AZ   85721
        U.S.A.
        [phone] (voice)
        [phone] (fax)
        [e-mail]     (Internet)
        ... {uunet, allegra, noao}!arizona!icon-project     (uucp)



11.__Registering_Copies_of_Icon

   If you received your copy of Icon directly from the Icon Pro-
ject, it has been registered in your name and you will automati-
cally receive the Icon Newsletter.  This newsletter contains
information about new implementations, updates, programming tech-
niques, and information of general interest about Icon.

   If you received your copy of Icon from another source, please
fill out the registration form that is included in the distribu-
tion and send it to the Icon Project at the address listed above.
This will assure that you receive the Icon Newsletter and infor-
mation about updates.

Acknowledgements

   The design and implementation of the Icon programming language
was supported, in part, by grants from the National Science Foun-
dation.

   Clint Jeffery, Gregg Townsend, and Ken Walker collaborated
with the author in the development of Version 8.5.

References


1.   R. E. Griswold and M. T. Griswold, The Icon Programming
     Language, Prentice-Hall, Inc., Englewood Cliffs, NJ, second
     edition, 1990.

2.   R. E. Griswold, C. L. Jeffery, G. M. Townsend and K. Walker,
     Version 8.5 of the Icon Programming Language, The Univ. of
     Arizona Icon Project Document IPD174, 1992.











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