include/smp/atomic.h

0001 /*                    The Quest Operating System
0002  *  Copyright (C) 2005-2010  Richard West, Boston University
0003  *
0004  *  This program is free software: you can redistribute it and/or modify
0005  *  it under the terms of the GNU General Public License as published by
0006  *  the Free Software Foundation, either version 3 of the License, or
0007  *  (at your option) any later version.
0008  *
0009  *  This program is distributed in the hope that it will be useful,
0010  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
0011  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0012  *  GNU General Public License for more details.
0013  *
0014  *  You should have received a copy of the GNU General Public License
0015  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
0016  */
0017
0018 #ifndef _ATOMIC_H_
0019 #define _ATOMIC_H_
0020
0021 #include "types.h"
0022
0023 /* Intel Manual 3A 8.10.6.7 recommends no more than one lock or
0024  * semaphore be present within each 128-byte aligned block of memory,
0025  * to reduce bus traffic. */
0026 #define LOCK_ALIGNMENT_LOG2 7
0027 #define LOCK_ALIGNMENT (1<<LOCK_ALIGNMENT_LOG2)
0028
0029 static inline uint32
0030 atomic_load_dword (uint32 * addr)
0031 {
0032   return *((volatile uint32 *) addr);
0033 }
0034
0035 static inline void
0036 atomic_store_dword (uint32 * addr, uint32 x)
0037 {
0038   *((volatile uint32 *) addr) = x;
0039 }
0040
0041 static inline uint32
0042 atomic_xchg_dword (uint32 * addr, uint32 x)
0043 {
0044   asm volatile ("xchgl %1,(%0)":"=r" (addr), "=ir" (x):"0" (addr), "1" (x));
0045   return x;
0046 }
0047
0048 #endif
0049
0050 /*
0051  * Local Variables:
0052  * indent-tabs-mode: nil
0053  * mode: C
0054  * c-file-style: "gnu"
0055  * c-basic-offset: 2
0056  * End:
0057  */
0058
0059 /* vi: set et sw=2 sts=2: */