Implement ArYieldProcessor() routine

sdk/xtdk/amd64/arfuncs.h

@@ -108,4 +108,8 @@ VOID
 ArWriteModelSpecificRegister(IN ULONG Register,
                              IN ULONGLONG Value);
 
+XTCDECL
+VOID
+ArYieldProcessor();
+
 #endif /* __XTDK_AMD64_ARFUNCS_H */

sdk/xtdk/i686/arfuncs.h

@@ -104,4 +104,8 @@ VOID
 ArWriteModelSpecificRegister(IN ULONG Register,
                              IN ULONGLONG Value);
 
+XTCDECL
+VOID
+ArYieldProcessor();
+
 #endif /* __XTDK_I686_ARFUNCS_H */

xtoskrnl/ar/amd64/cpufunc.c

@@ -592,3 +592,20 @@ ArWriteModelSpecificRegister(IN ULONG Register,
                    "a" (Low),
                    "d" (High));
 }
+
+/**
+ * Yields a current thread running on the processor.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+VOID
+ArYieldProcessor()
+{
+    asm volatile("pause"
+                 :
+                 :
+                 : "memory");
+}

xtoskrnl/ar/i686/cpufunc.c

@@ -551,3 +551,20 @@ ArWriteModelSpecificRegister(IN ULONG Register,
                  : "c" (Register),
                    "A" (Value));
 }
+
+/**
+ * Yields a current thread running on the processor.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+VOID
+ArYieldProcessor()
+{
+    asm volatile("pause"
+                 :
+                 :
+                 : "memory");
+}