arch/.unmaintained/m68k-pp-native/boot/callback.h

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #ifndef __CALLBACK_H__
   7 #define __CALLBACK_H__
   8
   9 /* This is a workaround for a bug in the current version of gcc:
  10
  11    gcc assumes that no one will touch %a4 after it is set up in crt0.o.
  12    This isn't true if a function is called as a callback by something
  13    that wasn't compiled by gcc (like FrmCloseAllForms()).  It may also
  14    not be true if it is used as a callback by something in a different
  15    shared library.
  16
  17    We really want a function attribute "callback" which will insert this
  18    progloue and epilogoue automatically.
  19
  20       - Ian */
  21
  22 register void *reg_a4 asm("%a4");
  23
  24 #define CALLBACK_PROLOGUE \
  25     void *save_a4 = reg_a4; asm("move.l %%a5,%%a4; sub.l #edata,%%a4" : :);
  26
  27 #define CALLBACK_EPILOGUE reg_a4 = save_a4;
  28
  29 #endif