/*
 * See the dyninst/COPYRIGHT file for copyright information.
 * 
 * We provide the Paradyn Tools (below described as "Paradyn")
 * on an AS IS basis, and do not warrant its validity or performance.
 * We reserve the right to update, modify, or discontinue this
 * software at any time.  We shall have no obligation to supply such
 * updates or modifications or any other form of support to you.
 * 
 * By your use of Paradyn, you understand and agree that we (or any
 * other person or entity with proprietary rights in Paradyn) are
 * under no obligation to provide either maintenance services,
 * update services, notices of latent defects, or correction of
 * defects for Paradyn.
 * 
 * This 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.
 * 
 * This 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <assert.h>
#include "dyninstAPI_RT/src/RTthread.h"

/**
 * atomic_set will do the following atomically:
 *    if (*val == 0) {
 *       *val = 1;
 *       return 1;
 *    }
 *    return 0;
 *
 * We need two versions since windows uses a different assembly syntax
 * (AT&T syntax on Linux and Intel on Windows)
 **/
#if defined(os_windows)
int atomic_set(volatile int *val)
{
   int result;
#ifdef _WIN64
   result = _InterlockedCompareExchange(val, 1, 0);
   return !result;
#else
   __asm
   {
      mov eax, 0 ;
      mov ebx, 1 ;
      mov ecx, val ;      
      lock cmpxchg [ecx],ebx ;
      setz al ;
      mov result, eax ;
   }   
#endif
   return result;
}
#else
static int atomic_set(volatile int *val)
{
   int result = 1;
   __asm__ __volatile__(
           "xchgl %0, %1\n"
           : "+r" (result), "+m" (*val)
           :: "memory");
   return !result;
}
#endif

int tc_lock_lock(tc_lock_t *tc)
{
   dyntid_t me;

   me = dyn_pthread_self();
   if (me == tc->tid)
      return DYNINST_DEAD_LOCK;

   while (!atomic_set(&tc->mutex));

   tc->tid = me;
   return 0;
}
