1 files changed, 160 insertions, 0 deletions
diff --git a/src/lib/sync.C b/src/lib/sync.C
new file mode 100644
index 000000000..a70761eef
--- /dev/null
+++ b/src/lib/sync.C
@@ -0,0 +1,160 @@
+#include <sys/sync.h>
+#include <sys/syscall.h>
+#include <assert.h>
+
+using namespace Systemcalls;
+
+//-----------------------------------------------------------------------------
+
+uint64_t futex_wait(uint64_t * i_addr, uint64_t i_val)
+{
+    return (uint64_t) _syscall2(FUTEX_WAIT,i_addr, (void *)i_val);
+}
+
+//-----------------------------------------------------------------------------
+
+uint64_t futex_wake(uint64_t * i_addr, uint64_t i_count)
+{
+    return (uint64_t) _syscall2(FUTEX_WAKE, i_addr, (void *)i_count);
+}
+
+//-----------------------------------------------------------------------------
+
+void barrier_init (barrier_t * o_barrier, uint64_t i_count)
+{
+    mutex_init(&(o_barrier->iv_mutex));
+    o_barrier->iv_event = 0;
+    o_barrier->iv_count = i_count;
+    o_barrier->iv_missing = i_count;
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+void barrier_destroy (barrier_t * i_barrier)
+{
+    assert(i_barrier->iv_missing == i_barrier->iv_count);
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+void barrier_wait (barrier_t * i_barrier)
+{
+    mutex_lock(&(i_barrier->iv_mutex));
+    --(i_barrier->iv_missing);
+    if(i_barrier->iv_missing > 0)
+    {
+        uint64_t l_event = i_barrier->iv_event;
+        mutex_unlock(&(i_barrier->iv_mutex));
+        do
+        {
+            futex_wait(&(i_barrier->iv_event), l_event);
+        } while (i_barrier->iv_event == l_event);
+    }
+    else
+    {
+        ++(i_barrier->iv_event);
+        i_barrier->iv_missing = i_barrier->iv_count;
+
+        // Wake em all up
+        futex_wake(&(i_barrier->iv_event), UINT64_MAX);
+        mutex_unlock(&(i_barrier->iv_mutex));
+    }
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+mutex_t * mutex_create()
+{
+    mutex_t * m = new mutex_t;
+    mutex_init(m);
+    return m;
+}
+
+//-----------------------------------------------------------------------------
+
+void mutex_init(mutex_t * o_mutex)
+{
+    o_mutex->iv_val = 0;
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+void mutex_destroy(mutex_t *& i_mutex)
+{
+    delete i_mutex;
+    i_mutex = NULL;
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+void mutex_lock(mutex_t * i_mutex)
+{
+#ifdef __IDEA_1
+    uint64_t l_count = __sync_val_compare_and_swap(&(i_mutex->iv_val),0,1);
+
+    if(l_count != 0)
+    {
+        if (l_count != 2)
+            l_count = __sync_lock_test_and_set(&(i_mutex->iv_val), 2);
+
+        while( l_count != 0 )
+        {
+            futex_wait( &(i_mutex->iv_val), 2);
+            l_count = __sync_lock_test_and_set(&(i_mutex->iv_val),2);
+            // if more than one thread gets out - one continues while
+            // the rest get blocked again.
+        }
+    }
+#endif
+
+    // Idea # 2
+    while(1)
+    {
+        uint64_t l_count = __sync_val_compare_and_swap(&(i_mutex->iv_val),0,1);
+        if( 0 == l_count ) // uncontended lock
+        {
+            break;
+        }
+        else if ( 2 == l_count ) // already contended
+        {
+            futex_wait( &(i_mutex->iv_val), l_count);
+        }
+        else if ( 1 == l_count ) // lock now contended
+        {
+            if (__sync_bool_compare_and_swap(&(i_mutex->iv_val),1,2))
+            {
+                futex_wait( &(i_mutex->iv_val), 2);
+            }
+        }
+    }
+
+    return;
+}
+
+//-----------------------------------------------------------------------------
+
+void mutex_unlock(mutex_t * i_mutex)
+{
+#ifdef __IDEA_1
+    if (__sync_fetch_and_sub(&(i_mutex->iv_val), 1) != 1)
+    {
+        i_mutex->iv_val = 0; // the thread that is started will set this back to 2
+        futex_wake(&(i_mutex->iv_val), 1); // wake one thread
+    }
+#endif
+    // #idea 2
+    uint64_t l_count = __sync_lock_test_and_set(&(i_mutex->iv_val),0);
+    if(2 == l_count)
+    {
+        futex_wake(&(i_mutex->iv_val), 1); // wake one thread
+    }
+ 
+    return;
+}
+
+