Espresso 0.0.2c

lib/sync.c

@@ -0,0 +1,40 @@
+
+
+#include <sync.h>
+
+
+void spinlock_init(spinlock_t* lock)
+{
+  lock->locked = 0;
+}
+
+static inline int atomic_xchg(volatile int* addr, int newval)
+{
+  int result;
+
+  asm volatile (
+    "xchg %0, %1"
+    : "=r"(result), "+m"(*addr)
+    : "0"(newval)
+    : "memory"
+  );
+
+  return result;
+}
+
+void spin_lock(spinlock_t* lock)
+{
+  while (atomic_xchg(&lock->locked, 1))
+  {
+    while (lock->locked)
+    {
+      asm volatile("pause");
+    }
+  }
+}
+
+void spin_unlock(spinlock_t* lock)
+{
+  __atomic_clear(&lock->locked, __ATOMIC_RELEASE);
+}
+