Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-02/p_pascal.zip/READ.ME

Text File | 1990-06-02 | 21KB | 488 lines

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                       ALL RIGHTS RESERVED.

DISCLAIMER:

     These programs are  provided to the public domain  as a ser-
     vice  to   programmers.  They  may  be   copied  freely  and
     distributed  for  educational  purposes  with  the following
     restrictions:

     1. Commercial resale of  these programs, or incorporation of
     these programs into other  systems for commercial resale, in
     source code or  in compiled versions of the  source code, is
     prohibited.

     2.  Charges for  reproduced copies  must be  limited to cost
     (disks, postage and handling).

     3.  Any modifications  to the  programs from  the originally
     distributed version  must be clearly indicated,  both in the
     source  code and  the documentation.  Any such modifications
     should  retain the  genealogy of  the program,  both in  the
     source code, sign-on message, and documentation.

     4.  All  documentation  and   notices  supplied  with  these
     programs must be included in any reproduced versions.

     5.  All warranties  connected with  these programs  are dis-
     claimed. In particular, the author assumes no responsibility
     that  the programs  will operate  as documented,  nor is the
     author  responsible for  direct, indirect,  or consequential
     damages.  Any  and  all  risk  associated  with  using these
     programs, in whole or in part, is the user's.


=================================================================

Note: Directions for using this  system are included below and in
the a:\samples directory. For information about advanced versions
of this  system, or about versions  customized to run efficiently
on computers with different  architectures, contact the author at
the address given below.

This  is  a  portable  Standard  Pascal  system,  with some C ex-
tensions.  It implements  advanced Pascal  capabilities, such  as
procedures  and  functions  passed   as  parameters,  and  allows
"conformant arrays" to be passed  as pointers. Records and arrays
are all automatically  packed down to the character  level. The C
extensions, such  as masking and shifting  operations, the `halt'
command,  the `system'  call, and  C-style file  inclusion during
translation,  are illustrated  by examples  in the  demonstration
programs of the a:\samples directory.  This version of the system
is limited to  seven open data and textfiles  at any point during
program execution.  The full version, that  permits as many files
as available from your operating  system, and comes with portable
ANSI C source code, can be ordered from the address at the end of
this file.

Modern college-level  Pascal programming textbooks,  such as "Oh!
Pascal", by  Cooper and Clancy, give  examples of Pascal programs
that will run on this system.

The enclosed  Pascal to p-code translator  and p-code interpreter
is a companion system to the  Pascal to C translator, that can be
ordered from the address at the end of this file.

These portable systems are written entirely in ANSI C. The Pascal
to C translator is based on the p-code interpreter, but generates
optimizable C code that runs  almost as fast as programs compiled
directly from C code. The source is written to be compiled easily
under the DOS 3.2 and  later operating systems (and other systems
also, with minor changes in the "pascal.h" and "p-code.h" files).

K & R versions of the system can be obtained from the author.

As  a  demonstration  of  this,  the  "primes.exe" program in the
\samples  directory  of  this  diskette  was  compiled  from  the
"\samples\primes.pas" program after a Pascal to C translation.


=================================================================

DIRECTIONS

The following reserved words and standard names are recognized by
the system and operate in a standard fashion (with exceptions for
pack and unpack):

Standard Names:

false,    true,     input,    output,   get,      put,      reset,
rewrite,  read,     write,    pack,     unpack,   new,      dispose,
readln,   writeln,  page,     mark,     release,  halt,     abs,
sqr,      round,    trunc,    odd,      ord,      chr,      pred,
succ,     eof,      eoln,     system,   sin,      cos,      exp,
sqrt,     ln,       arctan,   integer,  real,     char,     boolean,
text,     nil,      maxint,   sethigh,  ordmaxchar


Reserved Words:

if,       do,       of,       to,       in,       or,       and,
not,      xor,      shl,      shr,      end,      for,      var,
div,      mod,      set,      then,     else,     with,     goto,
case,     type,     file,     begin,    until,    while,    array,
const,    label,    repeat,   record,   downto,   packed,   forward,
program,  function, procedure


1) Typing `TRANSLATE <Enter>' will  bring up the following direc-
tions for use:


Portable ISO Standard Pascal in C, version 3.8, May 31 1990.
All rights reserved.

The calling sequence is

  translator  source.pas  object.pcd  [optional directives]
or
  translator con  object.pcd /c+  [optional directives]

with `source.pas'  or `con' (the  keyboard) as the  Pascal source
code file and `object.pcd' serving as the output `p-code' file.

The source and  output file names are optionally  followed by one
or more Pascal translator directives from the list below:

/c+ Generate P-Code                /l- Turn Off Program Listing
/o+ Send P-Code to Source Listing  /t+ Print Translator Symbol Tables
/d+ All Run-Time Checks            /y+ Special Error Messages
/z+ Run-Time Zero Division Checks  /s+ Run-Time Stack Checks
/r+ Run-Time Set Element/Index/Pointer Range Checks

Note  that c-  (syntax-checking only)  is the  default c  option.
Here,  the  usual  C  command-line  convention  applies, in which
options are separated by blanks and  are preceded by either a `-'
or a `/'.


2)  Typing `INTERPRET <Enter>' will bring up the following direc-
tions for use:

Near arrays Pascal P-Code interpreter, version 3.8, May 31 1990.
All rights reserved.

The correct calling sequence is:

 interpreter a_program.pcd [path1][pr1] ... [pathn][prn]

with  executable p-code  stored in  the file  a_program.pcd and n
[optional] external files pr1 through  prn. Files pr1 through prn
may have path prefixes appropriate  to your operating system. The
pr1  through  prn  names  are  declared  in  the Pascal "Program"
statement, and any information about the directories in which the
files are located  is included on the command  line. The standard
Pascal Input and Output files behave exactly like the C stdin and
stdout files.

A more elaborate explanation follows below.


NOTES ON USING THE TRANSLATOR:


FEATURES AND RESTRICTIONS

This is a standard Pascal in C implementation compatible with the
Pascal taught in college textbooks  such as Oh! Pascal! by Cooper
and Clancy. The C implementation is portable, which means that it
will compile and  operate correctly on any computer  with a stan-
dard ANSI C compiler, and  will automatically adjust to different
CPU architectures.

This implementation limits sets to 64 members on 16-bit machines,
and string  constants to no  more than 80  characters apiece. Any
mix  of upper  and lower  case identifiers  and reserved words is
legal,  but only  the first  eight characters  of identifiers are
significant. European ascii alphabet letters may be used in iden-
tifiers. The  predeclared constant "Maxint" has  a value of 32767
for 16-bit CPUs  like the 8086, which means  that any long arith-
metic  must  be  done  using  REAL  numbers.  Anticipated  future
releases of this system will support long arithmetic.

Additional  minor restrictions:  procedures and  functions may be
passed as parameters, with the restrictions mentioned in standard
Pascal textbooks  for this capability;  e. g., 'Read',  'Readln',
'Write', and 'Writeln'  may not be passed as  parameters, but may
occur within  procedures/functions passed as  parameters. See the
"prfnparm.pas" program in the  \samples directory for examples of
functions  and procedures  passed as  parameters and  the use  of
textfiles.

The  `halt' or  `halt(integer_value)' command,  available on many
Pascal systems  as a nonstandard capability,  is also implemented
on this system, and behaves  like the C `exit' procedure. ('halt'
with no parameter  is translated to `exit(0)', and  `halt' with a
parameter is the corresponding call on `exit').

The 'Packed' and  'Unpacked' keywords may be used,  but they have
no effect;  instead, all character and  boolean arrays are stored
as packed  character arrays. Pack and  Unpack are implemented for
standard Pascal data types, but  the packing of Boolean arrays as
`bit  arrays' is  not supported.  An example  of "do it yourself"
packing and unpacking of bit  arrays using the shifting and mask-
ing   operators   is   included   in   the   \samples   directory
("truefalse.pas").

See  the yesno.pas  program in  the a:\samples  directory for ex-
amples of  string assignment and comparison  (ISO standard Pascal
version).

A  "System(packed_char_array)" function identical  in behavior to
the C  version of "system(char *)"  is implemented. If you  use a
Pascal packed char array instead of a string constant as argument
to the "System" function, be sure to intialize your array proper-
ly with a blank string constant of the correct size.

This new  version supports standard  Pascal data and  text files,
both  as  external  Pascal  files  and  as  local  files that are
automatically deleted at the end  of the procedure or function in
which  they  are  declared.  The  external  Pascal file names are
limited  to  eight  letters  and  must  appear  in the first line
"program xxxxx(a, b, ...);" statement. (These file namea may also
apear on the command line with Unix or Dos path prefixes.)

Pascal "Reset" is implemented by  rewinding the file and then is-
suing  a Pascal  "GET." A  Pascal "Rewrite"  deletes the file and
then reopens it.

The standard Pascal "New"  and "Dispose" procedures are available
for  acquiring individual  data nodes  and returning  them to the
Pascal heap. (The "optimized" use of  New, in which only parts of
a record are  allocated IS supported, but  users are cautioned to
debug their programs  first using the simple version  of New.) In
addition, "Mark" and "Release" are available for use in returning
entire blocks of data to  the heap, rather than individual nodes.
Programs can  be written using only  "New" and "Dispose", without
mention  of  "Mark"  and  "Release".  Or,  "New" (and optionally,
"Dispose") can be used in combination with "Mark" and "Release".

However,  while "New"  and "Dispose"  are relatively well-behaved
operations,  "Mark" and  "Release" have  to be  used carefully as
paired operations  that have side-effects. One  of these side ef-
fects is  that all data  nodes acquired by  "New" after a  "Mark"
operation are automatically disposed of by the call on "Release".
Furthermore, calls  on "Mark" and  "Release" are only  defined if
they  are paired  so each  call on  "Mark" is  balanced by a cor-
responding  call on  "Release". (The  a:\samples listtest.pas and
newtest.pas programs are examples of their use.)

The  enclosed   "Near  arrays"  version  of   the  Pascal  p-code
interpreter has  approximately 15,000 bytes  of Pascal heap  area
available for  "New" and "Dispose", the  "Far arrays" version has
62,400 bytes, and the "Huge arrays" version has 142,400 bytes.

Some small source program examples  are included in the "samples"
directory on  this diskette. They illustrate  the general form of
programs accepted  by the translator and  the required translator
options directives to precede programs.

=================================================================

TRANSLATOR OPTIONS:

In this  Pascal system, translator  options can appear  either on
the command line,  as noted above, or within  the program. Pascal
options behave  like C pragmas. Program  examples in the \samples
file  illustrate the  use of  translator options.  In particular,
"pi.pas" shows how to turn the translator listing on and off dur-
ing translation of that  program, and "factorial.pas" illustrates
use  of the  {$i+'file_name'} option  for including  files within
your programs.

  (*$ ... *) or {$ ... }

where the " ... " in the middle is some sequence of the following
options separated by commas:


       a+ causes division by zero tests to be inserted before all
       all run-time code for real and integer division.

       c+ causes p-code  to be written to the  ".pcd" file. If c+
       does  not appear,  or if  c- or  c is  written, the source
       program will  be checked for  correctness, but not  trans-
       lated.

       d+ causes the translator to put  all a+, r+, and s+ checks
       into  the  run-time  code.  These  checks  are  useful for
       program debugging,  but can cause programs  to run slowly.
       They  are partly  responsible for  Pascal's reputation for
       slowness.  Eliminating  these  checks  via  the  d- option
       improves  program  execution  speed  and  allows "flexible
       dimension" arrays (when no  range checking occurs). The d+
       option  can  be  turned  on  and  off  locally within your
       program by following it with a d- option.

       i+ causes the file whose quoted name follows to be read by
       the translator:

        i.  e., {$i+'a:\samples\round.p'}

       includes the  round.p file at  that point in  the program.
       The  file source  code has  to be  to be  correct for that
       point  in the  program where  its insertion  occurs. Up to
       seven levels  of file inclusion  from any source  file are
       allowed by the system. (For examples  of how to use the i+
       option,  refer to  the 'a:\samples\factorial.pas'  and the
       'a:\samples\truefalse.pas' files. The  C '#include' pragma
       behaves in similar fashion.)

       l+ causes  the program to  be listed to  the "stdout" file
       (the monitor screen). The  listing can be re-directed from
       the screen to the line printer using the ">" redi- rection
       operator  on the  command line.  l+ is  the default option
       (the listing  will appear if  l+ is omitted).  To turn off
       the listing, use l-. Programs will translate several times
       faster with the screen listing disabled.

       o+ causes  the translator to route  its translation of the
       source program  to the stdout  file, causing each  execut-
       able source statement to be followed by the p-code that it
       generates (the ".pcd" file will  be empty as a result, but
       must still be mentioned on the translator's command line).
       Default option is o-.

       r+ causes the translator to  insert run-time tests for set
       element-,  loop index-,  and pointer-in-range correctness.
       Setting r- or d- disables these tests.

       s+ causes  the run-time system to  test for stack overflow
       on entry to all procedures and functions. Setting s- or d-
       turns off these tests.

       t+ causes the translator to  write out its internal tables
       listing declared  constants, procedures, and  functions at
       the end  of the translation  pass. Its use  is to discover
       what  the translator  believes the  program variables  and
       procedures to be. Default option is t-.


Command line calling sequences for the translator and interpreter
are as described below. (See also the "a:do.bat" file.)

For the translator:
==================================================================

    translator  your_source_code.pas  p_code_output.pcd

or

    translator con  p_code_output.pcd

==================================================================

Note that the  .pcd file extension for the  output p-code file in
the example is necessary to  interface properly with both the in-
terpreter and the C code generator programs.

With `con' on the command line as illustrated above, programs can
be typed in from the keyboard  and translated one line at a time,
but editing is limited to the current line only. Refer to the DOS
manual description of the "copy  con output_file" command for in-
formation about how to use the console keyboard for program input
to the  translator. In particular,  "control-Z" or ^Z  is used as
the end of file mark to terminate source programs.

Files external to the program  are named in standard Pascal style
on the "Program xxxxx(Input, Output, File1, File2);" line of your
Pascal  program. These  external files  are names  of up to eight
letters  each (the  same as  Pascal identifiers),  and they match
file names (preceded by optional operating system pathnames) that
ap- pear on the command line of your program. Thus, for example,

         Program Fileptrs(Input, Output, Prr);
         ....
         ....
         END.

can be called by a command line sequence of the form:

         interpreter fileptrs.pcd c:\xxx\prr

or

         interpreter fileptrs.pcd a:\yyy\zzzz.prr

or even

         interpreter fileptrs.pcd prr

depending on the  file path designation that you,  the user, find
convenient to use.

Translator  listings  are  sent  to  the  screen,  unless DOS I/O
redirection is used:

=================================================================

  translator source.pas  object.pcd  >  lpt1 (* parallel printer *)

or

  translator source.pas  object.pcd  >  com1 (* serial printer *)

or

  translator source.pas  object.pcd  >  a:listing.asc

=================================================================



NOTES ON USING THE Interpreter:

Interpreter command line with optional files in brackets:

=================================================================

   interpreter  p_code_input.pcd [path1][file1] [path2][file2]

=================================================================

The interpreter also has available  the standard Pascal Input and
Output files,  known in the  C language as  stdin and stdout.  So
programs translated for the interpreter can access Input (stdin),
Output (stdout),  and as many external  and internal Pascal files
as  your  system  will  allow.  See  the a:\samples directory for
examples of how to use files.

Note that the interpreter has some limitations, most important of
which is that sets can have up  to 64 members. This is a complete
Standard Pascal  otherwise. It is intended  as a teaching system,
with the  p-code interpreter to  be used by  students in compiler
courses. Thus, the p-code output  from the translator is in ascii
format, so that it can be  inspected and compared with the source
code  and used  in conjunction   with the  source code  to p-code
cross-reference generated in the translator listings.

=================================================================

SOURCES OF INFORMATION:

The reference for a previous  version of the Pacal translator and
its p-code interpreter, including  comments for the Pascal source
code, is in the book:

   Pemberton, S. Pascal Implementation. Ellis-Horwood Publishers,
      Ltd., England, 1981.

The  authors  of  the  Pascal  version  of  the  portable  Pascal
translator are U.  Ammann, K. Nori, and C.  Jacobi. K. Jensen, N.
Wirth, and C.  Jacobi wrote the Pascal version  of the p-code in-
terpreter.

The ANSI C version of these systems implements an advanced p-code
that is not  compatible with the p-code of  the Pascal system and
provides numerous  capabilities, e. g.,  procedures and functions
passed  as parameters,  conformant arrays,  full data  files, not
included in the Pascal version.

Translator  error  messages  use  the  error  number  format that
appears  in the  Pascal User  Manual listed  below and in several
Pascal and C compilers as well:

    Jensen, K. and Wirth,  N.  Pascal  User  Manual  and  Report.
         Springer Publishing Co., 1974.

=================================================================

As of June, 1990, the price of the DOS version of the full Pascal
to P-Code Translator/Interpreter with C source code was $50 post-
paid, and the Pascal to C  translator with C source code was also
$50 postpaid. (Specify 3-1/2" or  5-1/4" diskettes; if no size is
specified, 5-1/4" diskettes will be  sent. Payment is by check or
money order.  Orders from outside  the U. S.  please add $10  per
order for shipping.)


Address for orders and inquiries:

    Victor Schneider
    Suite 3QD
    291 Summit Avenue
    Brighton, MA 02146
    USA