/* Create new context.

   Copyright (C) 2008-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Helge Deller <deller@gmx.de>, 2008.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library.  If not, see

   <http://www.gnu.org/licenses/>.  */

#include <libintl.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <sysdep.h>

#include <ucontext.h>

/* POSIX only supports integer arguments.  */

/* Stack must be 64-byte aligned at all times.  */

#define STACK_ALIGN 64

/* Size of frame marker in unsigned long words.  */

#define FRAME_SIZE_UL 8

/* Size of frame marker in bytes.  */

#define FRAME_SIZE_BYTES (8 * sizeof(unsigned long))

/* Size of X arguments in bytes.  */

#define ARGS(x) (x * sizeof(unsigned long))

void

__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)

{

  unsigned long *sp, *osp;

  va_list ap;

  int i;

  /* Create a 64-byte aligned frame to store args. Use ss_sp if

     it is available, otherwise be robust and use the currently

     saved stack pointer.  */

  if (ucp->uc_stack.ss_sp && ucp->uc_stack.ss_size)

    osp = (unsigned long *)ucp->uc_stack.ss_sp;

  else

    osp = (unsigned long *)ucp->uc_mcontext.sc_gr[30];

  sp = (unsigned long *)((((unsigned long) osp)

			   + FRAME_SIZE_BYTES + ARGS(argc) + STACK_ALIGN)

			 & ~(STACK_ALIGN - 1));

  /* Use new frame.  */

  ucp->uc_mcontext.sc_gr[30] = ((unsigned long) sp);

  /* Finish frame setup.  */

  if (ucp->uc_link)

    {

      /* Returning to the next context and next frame.  */

      sp[-4/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[30];

      sp[-20/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[2];

    }

  else

    {

      /* This is the main context. No frame marker, and no return address.  */

      sp[-4/sizeof(unsigned long)] = 0x0;

      sp[-20/sizeof(unsigned long)] = 0x0;

    }

  /* Store address to jump to.  */

  ucp->uc_mcontext.sc_gr[2] = (unsigned long) func;

  /* Process arguments.  */

  va_start (ap, argc);

  for (i = 0; i < argc; ++i)

    {

      if (i < 4)

	{

	  ucp->uc_mcontext.sc_gr[26-i] = va_arg (ap, int);

	  continue;

	}

      if ((i < 8) && (sizeof(unsigned long) == 8))

	{

	  /* 64bit: r19-r22 are arg7-arg4.  */

	  ucp->uc_mcontext.sc_gr[22+4-i] = va_arg (ap, int);

	  continue;

	}

      /* All other arguments go on the stack.  */

      sp[-1 * (FRAME_SIZE_UL + 1 + i)] = va_arg (ap, int);

    }

  va_end (ap);

}

weak_alias(__makecontext, makecontext)