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      1 /*
      2  * ptw32_getprocessors.c
      3  *
      4  * Description:
      5  * This translation unit implements routines which are private to
      6  * the implementation and may be used throughout it.
      7  *
      8  * --------------------------------------------------------------------------
      9  *
     10  *      Pthreads-win32 - POSIX Threads Library for Win32
     11  *      Copyright(C) 1998 John E. Bossom
     12  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
     13  *
     14  *      Contact Email: rpj (at) callisto.canberra.edu.au
     15  *
     16  *      The current list of contributors is contained
     17  *      in the file CONTRIBUTORS included with the source
     18  *      code distribution. The list can also be seen at the
     19  *      following World Wide Web location:
     20  *      http://sources.redhat.com/pthreads-win32/contributors.html
     21  *
     22  *      This library is free software; you can redistribute it and/or
     23  *      modify it under the terms of the GNU Lesser General Public
     24  *      License as published by the Free Software Foundation; either
     25  *      version 2 of the License, or (at your option) any later version.
     26  *
     27  *      This library is distributed in the hope that it will be useful,
     28  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
     29  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     30  *      Lesser General Public License for more details.
     31  *
     32  *      You should have received a copy of the GNU Lesser General Public
     33  *      License along with this library in the file COPYING.LIB;
     34  *      if not, write to the Free Software Foundation, Inc.,
     35  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
     36  */
     37 
     38 #include "pthread.h"
     39 #include "implement.h"
     40 
     41 
     42 /*
     43  * ptw32_getprocessors()
     44  *
     45  * Get the number of CPUs available to the process.
     46  *
     47  * If the available number of CPUs is 1 then pthread_spin_lock()
     48  * will block rather than spin if the lock is already owned.
     49  *
     50  * pthread_spin_init() calls this routine when initialising
     51  * a spinlock. If the number of available processors changes
     52  * (after a call to SetProcessAffinityMask()) then only
     53  * newly initialised spinlocks will notice.
     54  */
     55 int
     56 ptw32_getprocessors (int *count)
     57 {
     58   DWORD_PTR vProcessCPUs;
     59   DWORD_PTR vSystemCPUs;
     60   int result = 0;
     61 
     62 #if defined(NEED_PROCESS_AFFINITY_MASK)
     63 
     64   *count = 1;
     65 
     66 #else
     67 
     68   if (GetProcessAffinityMask (GetCurrentProcess (),
     69 			      &vProcessCPUs, &vSystemCPUs))
     70     {
     71       DWORD_PTR bit;
     72       int CPUs = 0;
     73 
     74       for (bit = 1; bit != 0; bit <<= 1)
     75 	{
     76 	  if (vProcessCPUs & bit)
     77 	    {
     78 	      CPUs++;
     79 	    }
     80 	}
     81       *count = CPUs;
     82     }
     83   else
     84     {
     85       result = EAGAIN;
     86     }
     87 
     88 #endif
     89 
     90   return (result);
     91 }
     92