1 files changed, 81 insertions, 0 deletions
diff --git a/mach/lowlevellock.h b/mach/lowlevellock.h
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+/* Low-level lock implementation.  Mach gsync-based version.
+   Copyright (C) 1994-2017 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; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _MACH_LOWLEVELLOCK_H
+#define _MACH_LOWLEVELLOCK_H   1
+
+#include <mach/gnumach.h>
+#include <atomic.h>
+
+/* Gsync flags.  */
+#ifndef GSYNC_SHARED
+  #define GSYNC_SHARED      0x01
+  #define GSYNC_QUAD        0x02
+  #define GSYNC_TIMED       0x04
+  #define GSYNC_BROADCAST   0x08
+  #define GSYNC_MUTATE      0x10
+#endif
+
+/* Static initializer for low-level locks.  */
+#define LLL_INITIALIZER   0
+
+/* Wait on address PTR, without blocking if its contents
+ * are different from VAL.  */
+#define lll_wait(ptr, val, flags)   \
+  __gsync_wait (__mach_task_self (),   \
+    (vm_offset_t)(ptr), (val), 0, 0, (flags))
+
+/* Wake one or more threads waiting on address PTR.  */
+#define lll_wake(ptr, flags)   \
+  __gsync_wake (__mach_task_self (), (vm_offset_t)(ptr), 0, (flags))
+
+/* Acquire the lock at PTR.  */
+#define lll_lock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     int __flags = (flags);   \
+     if (*__iptr != 0 ||   \
+         atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) != 0)   \
+       while (1)   \
+         {   \
+           if (atomic_exchange_acq (__iptr, 2) == 0)   \
+             break;   \
+           lll_wait (__iptr, 2, __flags);   \
+         }   \
+     (void)0;   \
+   })
+
+/* Try to acquire the lock at PTR, without blocking.
+   Evaluates to zero on success.  */
+#define lll_trylock(ptr)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     *__iptr == 0 &&   \
+       atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) == 0 ? 0 : -1;   \
+   })
+
+/* Release the lock at PTR.  */
+#define lll_unlock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     if (atomic_exchange_rel (__iptr, 0) == 2)   \
+       lll_wake (__iptr, (flags));   \
+     (void)0;   \
+   })
+
+#endif