1 /* Copyright (C) 2001 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3    Contributed by Jakub Jelinek <jakub@redhat.com>.
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14 
15    You should have received a copy of the GNU Lesser General Public
16    License along with the GNU C Library; if not, write to the Free
17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18    02111-1307 USA.  */
19 
20 #include <ucontext.h>
21 
22 #define UC_M_PC 40
23 #define UC_M_NPC 48
24 
25 extern int __getcontext (ucontext_t *ucp);
26 extern int __setcontext (const ucontext_t *ucp, int restoremask);
27 
28 int
29 swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
30 {
31   extern void __swapcontext_ret (void);
32   /* Save the current machine context to oucp.  */
33   __getcontext (oucp);
34   /* Modify oucp to skip the __setcontext call on reactivation.  */
35   *(long*)((char*)oucp+UC_M_PC) = (long)__swapcontext_ret;
36   *(long*)((char*)oucp+UC_M_NPC) = (long)__swapcontext_ret + 4;
37   /* Restore the machine context in ucp.  */
38   __setcontext (ucp, 1);
39   return 0;
40 }
41 
42 asm ("							\n\
43 	.text						\n\
44 	.type	__swapcontext_ret, #function		\n\
45 __swapcontext_ret:					\n\
46 	return	%i7 + 8					\n\
47 	 clr	%o0					\n\
48 	.size	__swapcontext_ret, .-__swapcontext_ret	\n\
49      ");
50