/*
 * 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 "src/RTthread.h"
#include <assert.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;
}