1  /* Copyright (C) 2001-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <ucontext.h>
      19  
      20  extern int __getcontext (ucontext_t *ucp);
      21  extern int __setcontext (const ucontext_t *ucp, int restoremask);
      22  
      23  int
      24  __swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
      25  {
      26    extern void __swapcontext_ret (void);
      27    /* Save the current machine context to oucp.  */
      28    __getcontext (oucp);
      29    /* Modify oucp to skip the __setcontext call on reactivation.  */
      30    oucp->uc_mcontext.mc_gregs[MC_PC] = (long) __swapcontext_ret;
      31    oucp->uc_mcontext.mc_gregs[MC_NPC] = ((long) __swapcontext_ret) + 4;
      32    /* Restore the machine context in ucp.  */
      33    __setcontext (ucp, 1);
      34    return 0;
      35  }
      36  
      37  asm ("							\n\
      38  	.text						\n\
      39  	.type	__swapcontext_ret, #function		\n\
      40  __swapcontext_ret:					\n\
      41  	return	%i7 + 8					\n\
      42  	 clr	%o0					\n\
      43  	.size	__swapcontext_ret, .-__swapcontext_ret	\n\
      44       ");
      45  
      46  weak_alias (__swapcontext, swapcontext)