h2pas(1) Free Pascal C header conversion utility h2pas(1)NAMEh2pas - The C header to pascal unit conversion program.
SYNOPSISh2pas [options] filename
DESCRIPTIONh2pas attempts to convert a C header file to a pascal unit. it can
handle most C constructs that one finds in a C header file, and
attempts to translate them to their pascal counterparts. see the CON‐
STRUCTS section for a full description of what the translator can han‐
dle.
USAGE
H2pas is a command-line tool that translates a C header file to a spas‐
cal unit. It reads the C header file and translates the C declarations
to equivalent pascal declarations that can be used to access code writ‐
ten in C.
The output of the h2pas program is written to a file with the same name
as the C header file that was used as input, but with the extension
.pp. The output file that h2pas creates can be customized in a number
of ways by means of many options.
OPTIONS
The output of h2pas can be controlled with the following options:
-d use external; for all procedure and function declarations.
-D use external libname name 'func_name' for function and procedure
declarations.
-e Emit a series of constants instead of an enumeration type for
the C enum construct.
-i create an include file instead of a unit (omits the unit
header).
-l libname
specify the library name for external function declarations.
-o outfile
Specify the output file name. Default is the input file name
with the extension replaced by .pp "."
-p use the letter P in front of pointer type parameters instead of
"^".
-s Strip comments from the input file. By default comments are con‐
verted to comments, but they may be displaced, since a comment
is handled by the scanner.
-t prepend typedef type names with the letter T (used to follow
Borland's convention that all types should be defined with T).
-v replace pointer parameters by call by reference parameters. Use
with care because some calls can expect a NIL pointer.
-w Header file is a win32 header file (adds support for some spe‐
cial macros).
-x handle SYS_TRAP of the PalmOS header files.
CONSTRUCTS
The following C declarations and statements are recognized:
defines
defines are changed into pascal constants if they are simple
defines. macros are changed - wherever possible to functions;
however the arguments are all integers, so these must be changed
manually. Simple expressions in define staments are recognized,
as are most arithmetic operators: addition, substraction, multi‐
plication, division, logical operators, comparision operators,
shift operators. The C construct ( A ? B : C) is also recognized
and translated to a pascal construct with an IF statement (this
is buggy, however).
preprocessor statements
the conditional preprocessing commands are recognized and trans‐
lated into equivalent pascal compiler directives. The special
#ifdef __cplusplus is also recognized and removed.
typedef
A typedef statement is changed into a pascal type statement. The
following basic types are recognized:
char changed to char.
float changed to real (=double in free pascal).
int changed to longint.
long changed to longint.
long int
changed to longint.
short changed to integer.
unsigned
changed to cardinal.
unsigned char
changed to byte.
unsigned int
changed to cardinal.
unsigned long int
changed to cardinal.
unsigned short
changed to word.
void ignored.
These types are also changed if they appear in the arguments of a func‐
tion or procedure.
functions and procedures
functions and procedures are translated as well; pointer types
may be changed to call by reference arguments (using the var
argument) by using the -p command line argument. functions that
have a variable number of arguments are changed to a function
with an array of const argument.
specifiers
the extern specifier is recognized; however it is ignored. the
packed specifier is also recognised and changed with the PACK‐
RECORDS directive. The const specifier is also recognized, but
is ignored.
modifiers
If the -w option is specified, then the following modifiers are
recognized: STDCALL , CDECL , CALLBACK , PASCAL , WINAPI , API‐
ENTRY , WINGDIAPI as defined in the win32 headers. If addition‐
ally the -x option is specified then the SYS_TRAP specifier is
also recognized.
enums enum constructs are changed into enumeration types; bear in mind
that in C enumeration types can have values assigned to them;
Free Pascal also allows this to a certain degree. If you know
that values are assigned to enums, it is best to use the -e
option to change the enus to a series of integer constants.
unions unions are changed to variant records.
structs
are changed to pascal records, with C packing.
SEE ALSOppc386(1)ppumove(1)Free Pascal 12 Dec 1999 h2pas(1)
