HP-UX Extensions

HP-UX extensions are available only to programs that are compiled by the HP Pascal compiler running on the HP-UX operating system. The programs themselves must also run on the HP-UX operating system. The HP-UX extensions are:

Access to special global variables through the EXTERNAL directive.
The predefined function get_alignment, which returns the alignment requirement of a given type or variable.
The predefined function statement_number, which returns the statement number of the statement that calls it.

Accessing Special Global Variables

The global variable errno is special in that a program can access it through the EXTERNAL directive.

Example

$EXTERNAL$
PROGRAM ErrorNo_Example;
 
VAR
   ErrorNumber $ALIAS 'errno'$ : INTEGER;
 
FUNCTION Pas_Errno : integer;
BEGIN
   Pas_Errno := ErrorNumber;
END;
 
BEGIN
END.

When another compilation unit is linked with the preceding program, it can access the function Pas_Errno, which returns the value of the global variable errno.

Fnum Function

The predefined function fnum returns the HP-UX file number of the physical file currently associated with a given logical file. You can use this file number in system calls.

Syntax

fnum (filename)

Parameter

filename: The name of the logical file. This parameter is required, even if the logical file is the standard file input or output. The logical file must be associated with a physical file.

Example

program xref(output);
const SEEK_SET=0;       { Set file pointer to "offset" }
      SEEK_CUR=1;       { Set file pointer to current plus "offset" }
      SEEK_END=2;       { Set file pointer to EOF plus "offset" }
 
var s_file : text;
    max    : integer;
    f      : integer;
 
function lseek(fildes:integer; offset:integer; whence:integer): integer;
   external;
 
begin
reset(s_file,'foo');
f:=fnum(s_file);
max:=lseek(f,0,seek_end);
writeln('file#:',f:1,', max bytes=',max:1);
end.

Output:

file#:3, max bytes=487

Get_alignment Function

The predefined function get_alignment returns the alignment requirement of a given type or variable.

Syntax

[get_alignment ( {variabletype})]

Parameters

variable: Any variable. The function get_alignment returns its alignment requirement.
type: Any type identifier (the name of any type). The function get_alignment returns its alignment requirement.

Example

PROGRAM prog;
 
TYPE
   Rec = $ALIGNMENT 8$
         RECORD
            f1 : integer;
            f2 : shortint;
            f3 : real;
         END;
 
   integer_ = $ALIGNMENT 2$ integer;
 
VAR
   ptr : ^integer_;
 
BEGIN
   i := get_alignment(rec);
 
   IF get_alignment(ptr^) > 2 THEN
      .
      .
      .
END.

Statement_number Function

The predefined function statement_number returns the statement number of the statement that calls it, as shown on the compiled listing. It is a useful debugging aid, especially when used with the predefined procedure assert.

Syntax

statement_number

Example

PROGRAM prog (output);
 
VAR
   i : integer;
 
BEGIN
   i := statement_number;
   writeln('Current Statement Number is ', i);
   assert(a > b, statement_number);
END.

HP-UX Extensions

Technical documentation

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Accessing Special Global Variables

Fnum Function

Get_alignment Function

Statement_number Function