h2pas

h2pas(1)            Free Pascal C header conversion utility           h2pas(1)



NAME
       h2pas - The C header to pascal unit conversion program.


SYNOPSIS
       h2pas [options] filename


DESCRIPTION
       h2pas  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 ALSO
              ppc386(1) ppumove(1)



Free Pascal                       12 Dec 1999                         h2pas(1)