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diff --git a/hifi/xaf/hifi-dpf/include/lib/mutex.h b/hifi/xaf/hifi-dpf/include/lib/mutex.h
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+/*******************************************************************************
+* Copyright (C) 2018 Cadence Design Systems, Inc.
+* 
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to use this Software with Cadence processor cores only and 
+* not with any other processors and platforms, subject to
+* the following conditions:
+* 
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+* 
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+******************************************************************************/
+
+/*******************************************************************************
+ * mutex.h
+ *
+ *
+ * Implementation of "non-robust" Szymanski linear-waiting algorithm. Types of
+ * failures tolerated by Szymanski's "robust" algorithm are not specific for
+ * Xtensa DSP cluster and therefore more lightweight version of the algorithm
+ * is used. FIFO servicing property is of low importance, and faster/smaller
+ * version with linear-wait property is preferable.
+ *
+ * We assume there is just a single mutex in the system, and all communication
+ * variables are defined somewhere in board-specific headers and imported here
+ * by means of macros MUTEX_SHARED_READ/WRITE.
+ ******************************************************************************/
+
+#ifndef __MUTEX_H
+#define __MUTEX_H
+
+/*******************************************************************************
+ * Imported macros
+ ******************************************************************************/
+
+#if !defined(MUTEX_SHARED_READ) || !defined(MUTEX_SHARED_WRITE)
+#error "Macros MUTEX_SHARED_READ and/or MUTEX_SHARED_WRITE not defined"
+#endif
+
+/*******************************************************************************
+ * Entry points
+ ******************************************************************************/
+
+/* ...acquire global mutex from i-th core */
+extern void mutex_lock(u32 i);
+
+/* ...release global mutex from i-th core */
+extern void mutex_unlock(u32 i);
+
+#endif  /* __MUTEX_H */