HP 3000 Manuals HP 3000 Manuals
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[REV
BEG] can use this file number in system calls.[REV END]
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 ({variable})
{type }
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.