This directory contains C header files containing
operating-system-specific definitions.  Each file describes a
particular operating system.  The emacs configuration script edits
../config.h to include the appropriate one of these files, and then
each emacs source file includes config.h.

General XEmacs Changes
---------------------------
The following is a list of those changes made globally across all
files.  They are not marked individually in each header file.  All
other changes should be preceded by a comment /* XEmacs change */.


1. Removed all #defines of [read|write|open|close].  This is now
   handled automatically by checking the INTERRUPTIBLE_IO etc. flags.

2. Removed all instances of #undef SIGIO and replaced them with
   #define BROKEN_SIGIO.  Jamie says:

   /* use BROKEN_SIGIO instead of this kludge -- jwz */

3. All instances of HAVE_GETWD, HAVE_DUP2, HAVE_UNISTD_H, NEED_UNISTD_H,
   HAVE_GETTIMEOFDAY and NEED_REALPATH removed.  We detect these
   automatically with configure.

4. All instances of HAVE_X11 replaced with HAVE_X_WINDOWS.  We don't
   support X10 or earlier so the HAVE_X11 define was purged.

5. Most of the signal crap (e.g. redefining sigsetmask, defining
   POSIX_SIGNALS) has been removed.  There are four possible
   signal paradigms that all systems fall into, and we auto-detect
   them in configure and handle them in syssignal.h.

6. Removed references to INTERRUPT_INPUT.  XEmacs does not use
   this bizarre way of reading input.

7. Removed references to BROKEN_FIONREAD.  FIONREAD is used only
   in INTERRUPT_INPUT and in the select() emulator, neither of
   which are supported in XEmacs.

8. Removed references to NOMULTIPLEJOBS.  This is unused in XEmacs
   and in FSF Emacs.

9. Removed references to HAVE_WAIT_HEADER and WAIT_USE_INT.
   They are unnecessary with the cleaned up syswait.h in XEmacs.
   (We autodetect sys/wait.h).  Instead, #define or #undef
   HAVE_UNION_WAIT.

10. Removed BSTRING.  Not used anywhere. (If the header file
    says there are bugs in bcopy() or the like, however, a
    #define BROKEN_BCOPY is added for reference.)

11. Removed #defines of bcopy, bzero, bcmp, index, rindex.
    XEmacs makes consistent use of the ANSI-equivalent
    functions memcpy, memset, memcmp, strchr, strrchr.

12. '#define subprocesses' removed.  Use '#define NO_SUBPROCESSES'
    if they don't exist.

13. References to HAVE_VFORK removed.  configure detects this.

14. Removed references to SYSV_SYSTEM_DIR, NONSYSTEM_DIR_LIBRARY,
    HAVE_SOCKETS, HAVE_SYSVIPC.  configure detects these.

15. Removed defines of HAVE_TERMIOS, HAVE_TERMIO, HAVE_TCATTR (when
    HAVE_TERMIOS was also defined), and SIGNALS_VIA_CHARACTERS.  configure
    detects these and systty.h automatically defines HAVE_TCATTR when
    HAVE_TERMIOS is defined.

16. Removed SETPGRP_RELEASES_CTTY.  Not necessary any more, with
    fixed definitions of EMACS_SEPARATE_PROCESS_GROUP et al.

17. Removed defines of NLIST_STRUCT.  configure detects this.

18. Removed defines of _setjmp and _longjmp.  configure detects this.

19. Removed all '#define static' business.  Defines NO_REMAP instead.

20. Removed defines of HAVE_MACH_MACH_H.  configure detects this.

21. Removed KERNEL_FILE and LDAV_SYMBOL from most if not all files.
    getloadavg.c has all sorts of conditional defns to define these.

22. Got rid of most PTY-related stuff.  We try hard to autodetect the
    proper way of allocating PTY's.  Removed HAVE_PTYS defn.

23. Removed HAVE_SOCKETS, we autodetect this.

24. Removed CLASH_DETECTION; this is now a configurable option.

25. Removed BSD_PGRPS; this is autodetected.

26. Removed NARROWPROTO; this is autodetected.

27. Removed LIBS_DEBUG, C_DEBUG_SWITCH, C_OPTIMIZE_SWITCH.
    None of them are used any more.  Any such stuff goes into
    configure.ac.