"preparser" is a little tool to resolve special macros and conditional 
preprocessor code in C files. 

The special marcro and conditions are given in a control file.

The control file use the same syntax like the C preprocessor directives
"#define" and "#undef" plus a "#delete" command.
You can also use C-Comments in it.
Here are 2 implicit conditional defines in "preparser" for "#if 0"
and "#if 1" code segments.

Control file syntax:

#delete <item to delete>
#define <name> <value>
#undef <name>

<name> maybe also a function. 

/* example control file */
#delete #include <linux/isdn_compat.h>
#define GET_USER get_user
#define PUT_USER put_user
#define idev_kfree_skb(a,b) dev_kfree_skb(a)
#define COMPAT_HAS_NEW_SYMTAB
#undef COMPAT_HAS_NEW_SETUP
/* end of example control file */

What does the Programm ?
1. It copies a input file into a output file (or stdout) 
2. While copying it deletes all items given in #delete (exact string
   matching).
3. While copying it resolve the marcros given in the control file.
4. It resolve any "#ifdef" "#ifndef" "#if" related to the marcros given in
   the control file. Note: in the moment it don't calculate a value after
   an "#if" directive, if here is a "#define" in the control file for
   the string after "#if" and the value of that "#define" is empty, "#if" is
   handled as false, if a value is given it is handled as true. 
5. All items inside "strings" or C comments are not modified. 

Usage

   ./preparser [options] <input file> [output file]

     Valid options are:

  -d                  increase debug level
  -c,-C <controlfile> Use control file
  -?                  Usage ; printout this information


"preparser" was written to write Linux portable Linux kernel code (portable
in the sense "portable between various kernel versions") and to remove
experimental code from C files. This avoid that contructs based on
KERNELVERSION are going into standard kernel.


Karsten Keil
keil@isdn4linux.de

PS: If you like to get the source, request it by mail.