Initial doc add

tests/app_test_i2s_loopback/usb_device.h

@@ -0,0 +1,24 @@
+// Copyright (c) 2016-2018, XMOS Ltd, All rights reserved
+#ifndef __usb_device_h__
+#define __usb_device_h__
+
+#include <xs1.h>
+#include <xccompat.h>
+#include "usb_std_requests.h"
+#include "xud.h"
+
+XUD_Result_t USB_GetSetupPacket(XUD_ep ep_out, XUD_ep ep_in, REFERENCE_PARAM(USB_SetupPacket_t, sp));
+
+XUD_Result_t USB_StandardRequests(XUD_ep ep_out, XUD_ep ep_in,
+    NULLABLE_ARRAY_OF(unsigned char, devDesc_hs), int devDescLength_hs,
+    NULLABLE_ARRAY_OF(unsigned char, cfgDesc_hs), int cfgDescLength_hs,
+    NULLABLE_ARRAY_OF(unsigned char, devDesc_fs), int devDescLength_fs,
+    NULLABLE_ARRAY_OF(unsigned char, cfgDesc_fs), int cfgDescLength_fs,
+#ifdef __XC__
+    char * unsafe strDescs[],
+#else
+    char * strDescs[],
+#endif
+    int strDescsLength, REFERENCE_PARAM(USB_SetupPacket_t, sp), XUD_BusSpeed_t usbBusSpeed);
+
+#endif // __usb_device_h__