Porting HP Pascal/HP-UX Programs

If you plan to run your programs only on HP computers, the effort to port your programs between HP computers is minimal and the extra features that HP Pascal/HP-UX provides will make your programming much easier. However, if you plan to port your programs to another vendor's computer, the effort to do so will be proportional to your use of nonstandard HP Pascal/HP-UX extensions. Even if the system you are porting to has extensions, it is doubtful that the extensions on that system have the same form as extensions on HP Pascal/HP-UX.

To determine which features are nonstandard in an HP Pascal/HP-UX source file, include the $ANSI ON$ compiler option at the start of your source file or use the -A command-line option.

When you compile the source file using the -L command-line option, the compiler generates a listing file that shows where nonstandard features are used. Combined, the ANSI compiler option and the -L command-line option assure you that you are using only ANSI Standard Pascal features or that you are aware of where you are using nonstandard features.

Porting Between Series 300/400 and Series 700/800

This section summarizes some of the HP Pascal/HP-UX language features, both standard and nonstandard, that may cause problems when porting Pascal programs between Series 300/400 and Series 700/800 as well as to or from other systems.

Data Type Sizes and Alignments

Table 1-6 “HP Pascal/HP-UX Data Types” shows the sizes and alignments of the Pascal data types on HP-UX architectures. Packing significantly affects data type alignments and sizes. For more specific information, refer to HP Pascal/HP-UX Reference Manual; and HP Pascal/HP-UX Programmer's Guide.

On the Series 300/400, if the +A command-line option is specified, any data types larger than two bytes are aligned on a 2-byte boundary.

Table 1-6 HP Pascal/HP-UX Data Types

\Type	Size\(bytes)	Alignment\(300/400)	Alignment\(700/800)
`bit16`	2	Not supported	2
`bit32`	4	Not supported	4
`bit52`	8	Not supported	4
`boolean`	1	1-byte	1-byte
`char`	1	1-byte	1-byte
`enumeration`	2^[1]	2-byte	1-, 2-, or 4-byte, based on declared range
subrange of `enumeration`	2^[1]	same as host enumeration type	2-byte or 4-byte, based on declared range
$extnaddr$ pointer	8	Not supported	4
`integer`	4	4-byte	4-byte
subrange of `integer` ≥ -32768 AND ≤ 32767	2^[1]	2-byte	2-byte
subrange of `integer` < -32768 OR > 32767	4	4-byte	4-byte
`longint`	8	Not supported	4-byte
`longreal`	8	4-byte	8-byte
pointer	4	4-byte	4-byte
`real`	4	4-byte	4-byte
`set`	Varies	Varies	Varies
`shortint`	2	Not supported	2-byte
^[1]On Series 700/800, 1, 2, or 4 bytes can be allocated, depending on the declared range.

Control Constructs

The TRY/RECOVER construct is supported on all HP-UX implementations. Escape codes for errors differ significantly between the implementations.
The mark and release procedures are supported on all HP-UX implementations. There are minor differences in behavior but code is essentially portable.

Input/Output

Series 300/400 and 700/800 differ in the way each allows association with an HP-UX file descriptor in the reset procedure. The association is not similar in the associate procedure.
Series 700/800 uses an option string parameter on reset, rewrite, open, and append procedures. Series 300/400 ignores this parameter.
On the Series 700/800, if stdout is a terminal, the output is unbuffered. If stdout is a file, the output is line-buffered.
Series 300/400 requires the declaration of stderr after declaring it as a program parameter; Series 700/800 does not.
Series 700/800 implements the fnum function; Series 300/400 does not.
Series 300/400 and 700/800 differ in how each handles eof, get, and put with direct access files.
The close procedure has different default behavior on each system.

Modules

Modules are supported on all HP-UX implementations but some syntactic and semantic differences exist. For example, Series 700/800 requires that CONST, TYPE, and VAR declarations precede routine declarations within the EXPORT section, whereas Series 300/400 permits them to be intermixed.
Series 300/400 permits separate compilation only within modules. Series 700/800 can compile outside modules by using the SUBPROGRAM, GLOBAL, and EXTERNAL compiler options.

Assignment to Procedure Variables

Assignment to a procedure variable has a different syntax on each of the two architectures.

Maximum String Size

On the Series 300/400, the maximum string size is 255 characters. By specifying the LONGSTRINGS compiler option, maximum string size is virtually unlimited. The string size on Series 700/800 is unlimited.

ANYVAR Parameters

ANYVAR is supported on all HP-UX implementations. Series 300/400 does not perform checks to see if ANYVAR values are legitimate. Series 700/800 passes size information with ANYVAR parameters.

On the Series 300/400, elements of packed arrays can be passed as ANYVAR parameters if you use the ALLOW_PACKED compiler option.

Structured Constants

All HP-UX implementations support structured constants but different restrictions may apply. Series 300/400 restricts their use to the CONST section and it does not do full type checking on variant-record structured constants.

longreal Precision

There is a small difference in precision between the implementations of longreal because different bit-patterns are used.

anyptr, globalanyptr, and localanyptr

All HP-UX implementations have anyptr, although minor differences exist. On Series 700/800, anyptr is only assignment compatible, it is not type compatible with pointer types. anyptr is also a different size on Series 700/800: it is 64 bits.

globalanyptr and localanyptr are implemented only on Series 700/800.

Other Features

Program parameters have slight semantic differences between Series 300/400 and Series 700/800.
Arguments for the + operator with strings differ between Series 300/400 and Series 700/800. For example, chr cannot be used with + on Series 700/800.
Series 300/400 and Series 700/800 each generate different listings.

Features Supported only on Series 300/400

You can use the addr function to get the address of a constant.
A procedure alias is evaluated before addr(alias) is performed.
packed array of char does not require a lower bound of one for some operations.

Features Supported only on Series 700/800

waddress accepts NIL or a NIL-valued pointer.
A label is not allowed on the statement following a recover statement.
readonly parameters are allowed.
crunched arrays and records are allowed.

The following built-in functions are available:



   haveextension

   haveoptvarparam

   statement_number

   susizeof

The assert procedure is defined.
lobound subrange expressions that start with "(" are allowed.
Source is scanned that has been conditionally compiled out. This allows NLS characters in conditionally compiled sections of the source.
$STANDARD_LEVEL 'HP_MODCAL'$ must be used before importing an argument.
You must compile with $STANDARD_LEVEL 'EXT_MODCAL'$ to convert a pointer to an integer with ord(pointer_type),
packed array of char requires a lower bound of one.

Command-Line Options

Table 1-7 “Command-Line Options Specific to Series 300/400” summarizes the command-line options that are available only on the Series 300/400 or that behave differently on the Series 700/800.

Table 1-7 Command-Line Options Specific to Series 300/400

Command Option	Effect
`+A`	Use 2-byte alignment rules.
`+bfpa`	Affect floating-point operations.
`+ffpa`	Affect floating-point operations.
`+l`	Allow production of dynamically loaded libraries.
`-L`	Produce a program listing in a file specified by `$LIST` `filename``$`.
`+M`	Use library calls for floating point.
`+S`	Use 4-byte alignment rules.
`-T`	Same as $TABLES ON$ .
`+U`	Same as $ALLOW_PACKED ON$ .

Table 1-8 “Command-Line Options Specific to Series 700/800” summarizes the command line compiler options that are available only on the Series 700/800 or that behave differently on the Series 300/400.

Table 1-8 Command-Line Options Specific to Series 700/800

Command Option	Effect
`+C`	Convert MPE file names to HP-UX names.
`+DA``model`	Generate object code for a particular version of the PA-RISC architecture.
`+DS``model`	Perform instruction scheduling tuned for a particular implementation of the PA-RISC architecture.
`-L`	Produce a program listing to `stdout`.
`+N`	Turn off generation of notes.
`+O0`, `+O1`, `+O2`, `+O3`, `+O4`	Set optimization level.
`+O`[`no`]`aggressive`, `+O`[`no`]`all`, `+O`[`no`]`conservative`, `+O`[`no`]`limit`, `+O`[`no`]`size`, `+O`[`no`]`entrysched`, `+O`[`no`]`fastaccess`, `+O`[`no`]`fltacc`, `+O`[`no`]`initcheck`, `+O`[`no`]`libcalls`, `+O`[`no`]`moveflops`, `+O`[`no`]`pipeline`, `+O`[`no`]`procelim`, `+O`[`no`]`regionsched`, `+O`[`no`]`regreassoc`	Modify optimization.
`-S`	Produce assembly output.
`+k`	Generate long-displacement code sequences for referencing global data.
`-y`	Generate additional information needed by static analysis tools.
`+z` and `+Z`	Produce PIC object for shared libraries.

Compiler Options

The HP Pascal/HP-UX compilers support a wide range of compiler options. Some options are identical on all systems. Some options are unique to a particular system. Some options have different semantics and slightly different syntax from one system to the other. For portable code, keep compiler options to a minimum and avoid options that affect the semantics of the language or enable system level programming extensions. For example, avoid using the $SYSPROG$ option on the Series 300/400.

Table 1-9 “Compiler Options Specific to Series 300/400” lists options that are specific to Series 300/400 as well as options that have the same name on Series 700/800 but different semantics.

Table 1-9 Compiler Options Specific to Series 300/400

Compiler Option	Effect
`ALLOW_PACKED`	Allows `ANYVAR` parameter passing of fields in packed records and arrays, and `SIZEOF` using packed fields and arrays.
`ANSI`^[1]	The compiler issues an error message when it encounters a feature in the source code that is illegal in ANSI/ISO Standard Pascal. It must be placed at the top of the file.
`CODE`^[1]	Selects whether a code file is generated. This option is not allowed within a procedure body.
`CODE_OFFSETS`^[1]	Causes PC offsets to be included in the listing. This option is not allowed within a procedure body.
`DEBUG`	Causes line number debugging information to be included in the object code.
`FLOAT_HDW`	Controls generation of code for floating-point hardware.
`IF`/`ELSE`/`ENDIF`^[1]	Controls conditional compilation. Refer to the HP Pascal/HP-UX Reference Manual; for the Series 300/400 for details.
`LINENUM`	Sets listing line number.
`LINES`^[1]	Specifies number of lines per page on a listing. Default value is 60.
`LITERAL_ALIAS`^[1]	Determines the case-sensitivity of an alias name.
`LONGSTRINGS`	Extends the maximum length of strings from 255 characters to virtually any length.
`RANGE`^[1]	Does run-time checks for range errors.
`SAVE_CONST`	Controls scope of structured constants.
`SEARCH`^[1]	Specifies files to be used to satisfy `IMPORT` declarations. This option must be the last option on an option list.
`SEARCH_SIZE`	Changes number of external files that can be searched. The default is 9.
`STANDARD_LEVEL`^[1]	Defines the compatibility level with various versions of Pascal.
`TABLES`^[1]	Turns on the listing of symbol tables. `TABLES` cannot be used within a procedure body.
`UNDERSCORE`	Causes `ALIAS` parameters to have an underscore added as a prefix.
`XREF`^[1]	Used with `LIST ON`, the listing includes a cross reference for each function, procedure, and outer block.
^[1]Available with semantic differences on all HP-UX implementations.

Table 1-10 “Compiler Options Specific to Series 700/800” lists options that are specific to Series 700/800 as well as options that have the same name on Series 300/400 but different semantics.

Table 1-10 Compiler Options Specific to Series 700/800

Compiler Option	Effect
`ALIGNMENT`	Changes storage alignment for types other than strings and file types.
`ANSI`^[1]	The compiler issues an error message when it encounters a feature in the source code that is illegal in ANSI Standard Pascal. $ANSI ON$ is equivalent to $STANDARD_LEVEL 'ANSI'$ .
`ASSERT_HALT`	Causes the program to halt if the `assert` function fails.
`ASSUME`	Sets optimizer assumptions.
`BUILDINT`	Causes the compiler to build an intrinsic file rather than an object code file.
`CHECK_ACTUAL_PARM`	Sets level of type checking of actual parameters for separately compiled functions or procedures.
`CHECK_FORMAL_PARM`	Sets level of type checking of formal parameters for separately compiled functions or procedures.
`CODE`^[1]	Generates object code after parsing a compilation block.
`CODE_OFFSETS`^[1]	When $LIST ON$ is used, the compiler prints a table that contains the statement number and offset of each executable statement that it lists.
`CONVERT_MPE_NAME`	Converts file names in the `BUILDINT`, `INCLUDE`, `LISTINTR`, and `SYSINTR` compiler options from MPE format to HP-UX format.
`COPYRIGHT`	Causes a copyright string to be placed into object code.
`COPYRIGHT_DATE`	Sets the date that appears in the copyright notice. This option must be used with the `COPYRIGHT` compiler option.
`EXTERNAL`	Used in conjunction with the `GLOBAL` option, `EXTERNAL` enables you to compile one program as two or more compilation units.
`EXTNADDR`	Specifies long pointer accessing.
`GLOBAL`	Used in conjunction with the `EXTERNAL` option, `GLOBAL` enables you to compile one program as two or more compilation units.
`GPROF`	Generates code for profiling.
`HEAP_COMPACT`	When used with `HEAP_DISPOSE ON`, free space in the heap is concatenated.
`HEAP_DISPOSE`	The predefined procedure `dispose` frees space in the heap so that the predefined procedure `new` can reallocate it.
`HP_DESTINATION`	`HP_DESTINATION 'ARCHITECTURE'` generates object code for a particular version of of the PA-RISC architecture. `HP_DESTINATION 'SCHEDULER'` performs instruction scheduling tuned for a particular implementation of the PA-RISC architecture.
`IF`/`ELSE`/`ENDIF`^[1]	Controls conditional compilation. Refer to the HP Pascal/HP-UX Reference Manual; for the Series 700/800 for details.
`INLINE`	Causes a procedure call to be replaced by inline code.
`KEEPASMB`^[1]	Causes the compiler to preserve an assembly file for the source file.
`LINES`	Specifies number of lines per page on a listing. Default value is 59.
`LIST_CODE`	When used with `LIST ON`, a mnemonic listing of object code is produced.
`LISTINTR`	List an intrinsic file to a specified file.
`LITERAL_ALIAS`^[1]	$LITERAL_ALIAS ON$ causes the compiler to differentiate between uppercase and lowercase letters for aliases. $LITERAL_ALIAS OFF$ causes the compiler to downshift aliases.
`LOCALITY`	Causes a locality name to be written to the object file for performance.
`MLIBRARY`	Specifies an alternate file into which the module export text is to be written.
`NOTES`	Causes helpful compiler notes to be printed on the program listing.
`OPTIMIZE`	Sets the level of optimization.
`OS`	Specifies the operating system under which a program is to be run.
`RANGE`^[1]	The compiler generates range-checking code.
`S300_EXTNAMES`	Changes external names to a form consistent with Series 300/400 conventions.
`SEARCH`^[1]	Specifies one or more files for the compiler to search for module definitions.
`SHLIB_CODE`	Generates PIC object code that you can use to create libraries.
`SKIP_TEXT`	Causes the compiler to ignore source code.
`STANDARD_LEVEL`^[1]	Defines the compatibility level with various versions of Pascal.
`STATEMENT_NUMBER`	When enabled, the compiler generates a special instruction to identify a code sequence with its corresponding Pascal statement.
`SUBPROGRAM`	Causes the compiler to emit code for specified level-one routines only. This option enables you to compile selected routines of a program.
`SYMDEBUG`	Emits debugger information for `xdb`.
`SYSINTR`	Specifies the intrinsic file to be searched for information on intrinsic routines.
`TABLES`^[1]	When used with `LIST ON`, the listing includes an identifier map for each compilation block.
`TITLE`	Specifies the title to appear on subsequent pages of the program listing.
`UPPERCASE`	All external names, including aliases, are shifted to uppercase.
`VERSION`	Specifies a version stamp to be placed in the object file.
`XREF`^[1]	When used with `LIST ON`, the listing includes a cross reference for each function, procedure, and outer block.
^[1]Available with semantic differences on all HP-UX implementations.