Remove whitespace

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

diff --git a/compat_arch_x86.c b/compat_arch_x86.c
new file mode 100644 (file)
index 0000000..e08ac89
--- /dev/null
+++ b/compat_arch_x86.c
@@ -0,0 +1,129 @@
+/*
+ * compat_arch_x86.c
+ *
+ * Userspace RCU library - x86 compatibility checks
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * 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 <stdio.h>
+#include <pthread.h>
+#include <signal.h>
+#include <assert.h>
+#include <urcu/uatomic_arch.h>
+
+/*
+ * It does not really matter if the constructor is called before using
+ * the library, as long as the caller checks if __urcu_cas_avail < 0 and calls
+ * compat_arch_init() explicitely if needed.
+ */
+int __attribute__((constructor)) __urcu_cas_init(void);
+
+static pthread_mutex_t compat_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * -1: unknown
+ *  1: available
+ *  0: unavailable
+ */
+int __urcu_cas_avail = -1;
+
+/*
+ * Imported from glibc 2.3.5. linuxthreads/sysdeps/i386/pt-machine.h.
+ */
+
+int get_eflags (void)
+{
+       int res;
+       __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
+       return res;
+}
+
+void set_eflags (int newflags)
+{
+       __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
+}
+
+int compare_and_swap_is_available (void)
+{
+       int oldflags = get_eflags ();
+       int changed;
+       /* Flip AC bit in EFLAGS.  */
+       set_eflags (oldflags ^ 0x40000);
+       /* See if bit changed.  */
+       changed = (get_eflags () ^ oldflags) & 0x40000;
+       /* Restore EFLAGS.  */
+       set_eflags (oldflags);
+       /* If the AC flag did not change, it's a 386 and it lacks cmpxchg.
+       Otherwise, it's a 486 or above and it has cmpxchg.  */
+       return changed != 0;
+}
+
+unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old,
+                             unsigned long _new, int len)
+{
+       sigset_t newmask, oldmask;
+       int ret;
+
+       /* Disable signals */
+       ret = sigemptyset(&newmask);
+       assert(!ret);
+       ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+       assert(!ret);
+       ret = pthread_mutex_lock(&compat_mutex);
+       assert(!ret);
+
+       switch (len) {
+       case 1:
+       {
+               unsigned char result = *(unsigned char *)addr;
+               if (result == old)
+                       *(unsigned char *)addr = (unsigned char)_new;
+               return result;
+       }
+       case 2:
+       {
+               unsigned short result = *(unsigned short *)addr;
+               if (result == old)
+                       *(unsigned short *)addr = (unsigned short)_new;
+               return result;
+       }
+       case 4:
+       {
+               unsigned int result = *(unsigned int *)addr;
+               if (result == old)
+                       *(unsigned int *)addr = (unsigned int)_new;
+               return result;
+       }
+       }
+       /* generate an illegal instruction. Cannot catch this with linker tricks
+        * when optimizations are disabled. */
+       __asm__ __volatile__("ud2");
+       return 0;
+
+       ret = pthread_mutex_unlock(&compat_mutex);
+       assert(!ret);
+       ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
+       assert(!ret);
+}
+
+int __urcu_cas_init(void)
+{
+       if (__urcu_cas_avail < 0)
+               __urcu_cas_avail = compare_and_swap_is_available();
+       return __urcu_cas_avail;
+}