DPE: Support host build

If `-DHOST_BUILD=ON` is added to the CMake command line
then the DPE library will be built as a stand-alone
Linux program. Not tested on Windows.

It allows the rapid development, build and test cycles
of the DPE library in a native environment without
the need to execute the code on FVP.

Change-Id: I4923c2aba9636d96bfe1aca4e7d5b731270382fa
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
diff --git a/partitions/dice_protection_environment/test/host/client.c b/partitions/dice_protection_environment/test/host/client.c
new file mode 100644
index 0000000..ec96c70
--- /dev/null
+++ b/partitions/dice_protection_environment/test/host/client.c
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2024, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#include "dpe_client.h"
+#include "dpe_cmd_decode.h"
+
+#define CLIENT_ID_NS -1
+
+int32_t dpe_client_call(const char *cmd_input, size_t cmd_input_size,
+                        char *cmd_output, size_t *cmd_output_size)
+{
+    int32_t err;
+
+    err = dpe_command_decode(CLIENT_ID_NS,
+                             cmd_input, cmd_input_size,
+                             cmd_output, cmd_output_size);
+
+    return err;
+}