diff --git a/lib_xua/src/core/module_description b/lib_xua/module_description
similarity index 100%
rename from lib_xua/src/core/module_description
rename to lib_xua/module_description
diff --git a/lib_xua/src/core/module_build_info b/lib_xua/src/core/module_build_info
deleted file mode 100644
index 4520aab3..00000000
--- a/lib_xua/src/core/module_build_info
+++ /dev/null
@@ -1,37 +0,0 @@
-# This file describes how this module will affect the application
-# using it. The file is included in the Makefile of the main application.
-#
-# The module contributes to the build of the application by extending 
-# the following variables:
-#
-#   SOURCE_DIRS  - directories with source files to be included in the build
-#   INCLUDE_DIRS - directories to be added to the include path during the build 
-#   LIB_DIRS     - directories containing libraries to be linked into the build
-#
-# Note that all the source files in each directory in SOURCE_DIRS 
-# will be compiled (you do not need to name the files individually).
-# 
-
-# You can change the flags of a set of files using the SET_XCC_[lang]_FLAGS
-# functions. The first argument is a list of directories and the
-# second argument is the value to set the compile flags to. e.g.
-#
-# $(call SET_XCC_C_FLAGS, mydir1 mydir2, $(XCC_FLAGS) -g -O3)
-
-# You can change the flags of an individual file by setting the 
-# XCC_FLAGS_[filename] variable. e.g.
-#
-# XCC_FLAGS_myfile.xc = $(XCC_FLAGS) -fsubword-select
-
-# You can exclude particular files from the build even if they occur
-# within SOURCE_DIRS by adding the file name (with no path) to the 
-# EXCLUDE_FILES variable e..g
-#
-EXCLUDE_FILES += descriptors_2.rst
-
-XCC_FLAGS_endpoint0.c = -Os -mno-dual-issue $(XCC_FLAGS)
-XCC_FLAGS_dbcalc.xc = -Os -mno-dual-issue $(XCC_FLAGS)
-XCC_FLAGS_audiorequests.xc = -Os -mno-dual-issue $(XCC_FLAGS)
-XCC_FLAGS_flashlib_user.c = -Os -mno-dual-issue $(XCC_FLAGS)
-XCC_FLAGS_audioports.c = -Os -mno-dual-issue $(XCC_FLAGS)
-XCC_FLAGS_audioports.xc = -Os -mno-dual-issue $(XCC_FLAGS)
diff --git a/lib_xua/src/core/pll/pll.h b/lib_xua/src/core/pll/pll.h
deleted file mode 100644
index af761d72..00000000
--- a/lib_xua/src/core/pll/pll.h
+++ /dev/null
@@ -1,4 +0,0 @@
-void PllInit(chanend ?c);
-
-
-void PllMult(unsigned mult, chanend ?c);
diff --git a/lib_xua/src/core/support/locks/lock.h b/lib_xua/src/core/support/locks/lock.h
new file mode 100644
index 00000000..1a027a7f
--- /dev/null
+++ b/lib_xua/src/core/support/locks/lock.h
@@ -0,0 +1,25 @@
+/** @file       lock.h
+  * @brief      Functions for using hardware locks
+  * @author     Ross Owen, XMOS Limited
+  */
+
+#ifndef _LOCK_H_
+#define _LOCK_H_ 1
+
+typedef unsigned lock;
+
+/* Allocates and returns a lock resource - returns 0 if out of lock */
+lock GetLockResource();
+
+/* Claims the passed lock, this is a blocking call */
+void ClaimLock(lock l);
+
+/* Frees the passed lock */
+void FreeLock(lock l);
+
+/* De-allocated the passed lock resource */
+void FreeLockResource(lock l);
+
+
+
+#endif
diff --git a/lib_xua/src/core/audiostream/audiostream.c b/lib_xua/src/core/user/audiostream/audiostream.c
similarity index 100%
rename from lib_xua/src/core/audiostream/audiostream.c
rename to lib_xua/src/core/user/audiostream/audiostream.c
diff --git a/lib_xua/src/core/audiostream/audiostream.h b/lib_xua/src/core/user/audiostream/audiostream.h
similarity index 100%
rename from lib_xua/src/core/audiostream/audiostream.h
rename to lib_xua/src/core/user/audiostream/audiostream.h
diff --git a/lib_xua/src/core/user/hostactive/hostactive.c b/lib_xua/src/core/user/hostactive/hostactive.c
new file mode 100644
index 00000000..b8bd33ec
--- /dev/null
+++ b/lib_xua/src/core/user/hostactive/hostactive.c
@@ -0,0 +1,7 @@
+
+void UserHostActive(int active) __attribute__ ((weak));
+void UserHostActive(int active)
+{
+    return;
+}
+
diff --git a/lib_xua/src/core/user/hostactive/hostactive.h b/lib_xua/src/core/user/hostactive/hostactive.h
new file mode 100644
index 00000000..378848d3
--- /dev/null
+++ b/lib_xua/src/core/user/hostactive/hostactive.h
@@ -0,0 +1,2 @@
+
+void UserHostActive(int active);