pt-machine.h

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

/* Machine-dependent pthreads configuration and inline functions.
   CRIS version.
   Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#ifndef _PT_MACHINE_H
#define _PT_MACHINE_H   1

#ifndef PT_EI
# define PT_EI extern inline
#endif

extern long int testandset (int *spinlock);
extern int __compare_and_swap (long int *p, long int oldval, long int newval);

PT_EI long int
testandset (int *spinlock)
{
  register unsigned long int ret;

  /* Note the use of a dummy output of *spinlock to expose the write.  The
     memory barrier is to stop *other* writes being moved past this code.  */
  __asm__ __volatile__("clearf\n"
		       "0:\n\t"
		       "movu.b [%2],%0\n\t"
		       "ax\n\t"
		       "move.b %3,[%2]\n\t"
		       "bwf 0b\n\t"
		       "clearf"
		       : "=&r" (ret), "=m" (*spinlock)
		       : "r" (spinlock), "r" ((int) 1)
		       : "memory");
  return ret;
}


/* Get some notion of the current stack.  Need not be exactly the top
   of the stack, just something somewhere in the current frame.
   I don't trust register variables, so let's do this the safe way.  */
#define CURRENT_STACK_FRAME \
 ({ char *sp; __asm__ ("move.d $sp,%0" : "=rm" (sp)); sp; })

#endif /* pt-machine.h */