pstoraster/gpcheck.h

   1 /* Copyright (C) 1992, 1994 Aladdin Enterprises.  All rights reserved.
   2
   3   This file is part of GNU Ghostscript.
   4
   5   GNU Ghostscript is distributed in the hope that it will be useful, but
   6   WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
   7   to anyone for the consequences of using it or for whether it serves any
   8   particular purpose or works at all, unless he says so in writing.  Refer
   9   to the GNU General Public License for full details.
  10
  11   Everyone is granted permission to copy, modify and redistribute GNU
  12   Ghostscript, but only under the conditions described in the GNU General
  13   Public License.  A copy of this license is supposed to have been given
  14   to you along with GNU Ghostscript so you can know your rights and
  15   responsibilities.  It should be in a file named COPYING.  Among other
  16   things, the copyright notice and this notice must be preserved on all
  17   copies.
  18
  19   Aladdin Enterprises supports the work of the GNU Project, but is not
  20   affiliated with the Free Software Foundation or the GNU Project.  GNU
  21   Ghostscript, as distributed by Aladdin Enterprises, does not require any
  22   GNU software to build or run it.
  23 */
  24
  25 /*$Id$ */
  26 /* Interrupt check interface */
  27
  28 #ifndef gpcheck_INCLUDED
  29 #  define gpcheck_INCLUDED
  30
  31 /*
  32  * On some platforms, the interpreter must check periodically for user-
  33  * initiated actions.  (Eventually, this may be extended to all platforms,
  34  * to handle multi-tasking through the 'context' facility.)  Routines that
  35  * run for a long time must periodically call gp_check_interrupts(), and
  36  * if it returns true, must clean up whatever they are doing and return an
  37  * e_interrupted (or gs_error_interrupted) exceptional condition.
  38  * The return_if_interrupt macro provides a convenient way to do this.
  39  *
  40  * On platforms that require an interrupt check, the makefile defines
  41  * a symbol CHECK_INTERRUPTS.  Currently this is only the Microsoft
  42  * Windows platform.
  43  */
  44
  45 #ifdef CHECK_INTERRUPTS
  46 int gp_check_interrupts(P0());
  47 int gs_return_check_interrupt(P1(int code));
  48
  49 #  define process_interrupts() discard(gp_check_interrupts())
  50 #  define return_if_interrupt()\
  51     { int icode_ = gp_check_interrupts();\
  52       if ( icode_ )\
  53         return gs_note_error((icode_ > 0 ? gs_error_interrupt : icode_));\
  54     }
  55 #  define return_check_interrupt(code)\
  56     return gs_return_check_interrupt(code)
  57 #else
  58 #  define gp_check_interrupts() 0
  59 #  define process_interrupts() DO_NOTHING
  60 #  define return_if_interrupt() DO_NOTHING
  61 #  define return_check_interrupt(code)\
  62     return (code)
  63 #endif
  64
  65 #endif /* gpcheck_INCLUDED */