Documentation: Update copyrights to 2019.
[pub/lufa.git] / Demos / Device / LowLevel / AudioInput / Descriptors.c
index b8de373..1860b55 100644 (file)
-/*\r
-             LUFA Library\r
-     Copyright (C) Dean Camera, 2009.\r
-              \r
-  dean [at] fourwalledcubicle [dot] com\r
-      www.fourwalledcubicle.com\r
-*/\r
-\r
-/*\r
-  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)\r
-\r
-  Permission to use, copy, modify, and distribute this software\r
-  and its documentation for any purpose and without fee is hereby\r
-  granted, provided that the above copyright notice appear in all\r
-  copies and that both that the copyright notice and this\r
-  permission notice and warranty disclaimer appear in supporting\r
-  documentation, and that the name of the author not be used in\r
-  advertising or publicity pertaining to distribution of the\r
-  software without specific, written prior permission.\r
-\r
-  The author disclaim all warranties with regard to this\r
-  software, including all implied warranties of merchantability\r
-  and fitness.  In no event shall the author be liable for any\r
-  special, indirect or consequential damages or any damages\r
-  whatsoever resulting from loss of use, data or profits, whether\r
-  in an action of contract, negligence or other tortious action,\r
-  arising out of or in connection with the use or performance of\r
-  this software.\r
-*/\r
-\r
-/** \file\r
- *\r
- *  USB Device Descriptors, for library use when in USB device mode. Descriptors are special \r
- *  computer-readable structures which the host requests upon device enumeration, to determine\r
- *  the device's capabilities and functions.  \r
- */\r
\r
-#include "Descriptors.h"\r
-\r
-/** Device descriptor structure. This descriptor, located in FLASH memory, describes the overall\r
- *  device characteristics, including the supported USB version, control endpoint size and the\r
- *  number of device configurations. The descriptor is read out by the USB host when the enumeration\r
- *  process begins.\r
- */\r
-USB_Descriptor_Device_t PROGMEM DeviceDescriptor =\r
-{\r
-       .Header                 = {.Size = sizeof(USB_Descriptor_Device_t), .Type = DTYPE_Device},\r
-               \r
-       .USBSpecification       = VERSION_BCD(02.00),\r
-       .Class                  = 0x00,\r
-       .SubClass               = 0x00,\r
-       .Protocol               = 0x00,\r
-                               \r
-       .Endpoint0Size          = FIXED_CONTROL_ENDPOINT_SIZE,\r
-               \r
-       .VendorID               = 0x03EB,\r
-       .ProductID              = 0x2047,\r
-       .ReleaseNumber          = 0x0000,\r
-               \r
-       .ManufacturerStrIndex   = 0x01,\r
-       .ProductStrIndex        = 0x02,\r
-       .SerialNumStrIndex      = NO_DESCRIPTOR,\r
-               \r
-       .NumberOfConfigurations = 1\r
-};\r
-\r
-/** Configuration descriptor structure. This descriptor, located in FLASH memory, describes the usage\r
- *  of the device in one of its supported configurations, including information about any device interfaces\r
- *  and endpoints. The descriptor is read out by the USB host during the enumeration process when selecting\r
- *  a configuration so that the host may correctly communicate with the USB device.\r
- */\r
-USB_Descriptor_Configuration_t PROGMEM ConfigurationDescriptor =\r
-{\r
-       .Config = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_Descriptor_Configuration_Header_t), .Type = DTYPE_Configuration},\r
-\r
-                       .TotalConfigurationSize   = sizeof(USB_Descriptor_Configuration_t),\r
-                       .TotalInterfaces          = 2,\r
-\r
-                       .ConfigurationNumber      = 1,\r
-                       .ConfigurationStrIndex    = NO_DESCRIPTOR,\r
-                               \r
-                       .ConfigAttributes         = (USB_CONFIG_ATTR_BUSPOWERED | USB_CONFIG_ATTR_SELFPOWERED),\r
-                       \r
-                       .MaxPowerConsumption      = USB_CONFIG_POWER_MA(100)\r
-               },\r
-               \r
-       .AudioControlInterface = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},\r
-\r
-                       .InterfaceNumber          = 0,\r
-                       .AlternateSetting         = 0,\r
-                       \r
-                       .TotalEndpoints           = 0,\r
-                               \r
-                       .Class                    = 0x01,\r
-                       .SubClass                 = 0x01,\r
-                       .Protocol                 = 0x00,\r
-                               \r
-                       .InterfaceStrIndex        = NO_DESCRIPTOR                       \r
-               },\r
-       \r
-       .AudioControlInterface_SPC = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioInterface_AC_t), .Type = DTYPE_AudioInterface},\r
-                       .Subtype                  = DSUBTYPE_Header,\r
-                       \r
-                       .ACSpecification          = VERSION_BCD(01.00),\r
-                       .TotalLength              = (sizeof(USB_AudioInterface_AC_t) +\r
-                                                    sizeof(USB_AudioInputTerminal_t) +\r
-                                                                            sizeof(USB_AudioOutputTerminal_t)),\r
-                       \r
-                       .InCollection             = 1,\r
-                       .InterfaceNumbers         = {1},                        \r
-               },\r
-\r
-       .InputTerminal = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioInputTerminal_t), .Type = DTYPE_AudioInterface},\r
-                       .Subtype                  = DSUBTYPE_InputTerminal,\r
-               \r
-                       .TerminalID               = 0x01,\r
-                       .TerminalType             = TERMINAL_IN_MIC,\r
-                       .AssociatedOutputTerminal = 0x00,\r
-                       \r
-                       .TotalChannels            = 1,\r
-                       .ChannelConfig            = 0,\r
-                       \r
-                       .ChannelStrIndex          = NO_DESCRIPTOR,\r
-                       .TerminalStrIndex         = NO_DESCRIPTOR\r
-               },\r
-\r
-       .OutputTerminal = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioOutputTerminal_t), .Type = DTYPE_AudioInterface},\r
-                       .Subtype                  = DSUBTYPE_OutputTerminal,\r
-               \r
-                       .TerminalID               = 0x02,\r
-                       .TerminalType             = TERMINAL_STREAMING,\r
-                       .AssociatedInputTerminal  = 0x00,\r
-                       \r
-                       .SourceID                 = 0x01,\r
-                       \r
-                       .TerminalStrIndex         = NO_DESCRIPTOR                       \r
-               },\r
-\r
-       .AudioStreamInterface_Alt0 = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},\r
-\r
-                       .InterfaceNumber          = 1,\r
-                       .AlternateSetting         = 0,\r
-                       \r
-                       .TotalEndpoints           = 0,\r
-                               \r
-                       .Class                    = 0x01,\r
-                       .SubClass                 = 0x02,\r
-                       .Protocol                 = 0x00,\r
-                               \r
-                       .InterfaceStrIndex        = NO_DESCRIPTOR\r
-               },\r
-\r
-       .AudioStreamInterface_Alt1 = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},\r
-\r
-                       .InterfaceNumber          = 1,\r
-                       .AlternateSetting         = 1,\r
-                       \r
-                       .TotalEndpoints           = 1,\r
-                               \r
-                       .Class                    = 0x01,\r
-                       .SubClass                 = 0x02,\r
-                       .Protocol                 = 0x00,\r
-                               \r
-                       .InterfaceStrIndex        = NO_DESCRIPTOR\r
-               },\r
-               \r
-       .AudioStreamInterface_SPC = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioInterface_AS_t), .Type = DTYPE_AudioInterface},\r
-                       .Subtype                  = DSUBTYPE_General,\r
-                       \r
-                       .TerminalLink             = 0x02,\r
-                       \r
-                       .FrameDelay               = 1,\r
-                       .AudioFormat              = 0x0001\r
-               },\r
-               \r
-       .AudioFormat = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioFormat_t), .Type = DTYPE_AudioInterface},\r
-                       .Subtype                  = DSUBTYPE_Format,\r
-\r
-                       .FormatType               = 0x01,\r
-                       .Channels                 = 0x01,\r
-                       \r
-                       .SubFrameSize             = 0x02,\r
-                       .BitResolution            = 16,\r
-                       .SampleFrequencyType      = (sizeof(ConfigurationDescriptor.AudioFormat.SampleFrequencies) / sizeof(AudioSampleFreq_t)),\r
-               \r
-                       .SampleFrequencies        = {SAMPLE_FREQ(AUDIO_SAMPLE_FREQUENCY)}\r
-               },\r
-       \r
-       .AudioEndpoint = \r
-               {\r
-                       .Endpoint = \r
-                               {\r
-                                       .Header              = {.Size = sizeof(USB_AudioStreamEndpoint_Std_t), .Type = DTYPE_Endpoint},\r
-\r
-                                       .EndpointAddress     = (ENDPOINT_DESCRIPTOR_DIR_IN | AUDIO_STREAM_EPNUM),\r
-                                       .Attributes          = (EP_TYPE_ISOCHRONOUS | ENDPOINT_ATTR_SYNC | ENDPOINT_USAGE_DATA),\r
-                                       .EndpointSize        = AUDIO_STREAM_EPSIZE,\r
-                                       .PollingIntervalMS   = 1\r
-                               },\r
-                       \r
-                       .Refresh                  = 0,\r
-                       .SyncEndpointNumber       = 0\r
-               },\r
-               \r
-       .AudioEndpoint_SPC = \r
-               {\r
-                       .Header                   = {.Size = sizeof(USB_AudioStreamEndpoint_Spc_t), .Type = DTYPE_AudioEndpoint},\r
-                       .Subtype                  = DSUBTYPE_General,\r
-                       \r
-                       .Attributes               = 0x00,\r
-                       \r
-                       .LockDelayUnits           = 0x00,\r
-                       .LockDelay                = 0x0000\r
-               }\r
-};\r
-\r
-/** Language descriptor structure. This descriptor, located in FLASH memory, is returned when the host requests\r
- *  the string descriptor with index 0 (the first index). It is actually an array of 16-bit integers, which indicate\r
- *  via the language ID table available at USB.org what languages the device supports for its string descriptors.\r
- */\r
-USB_Descriptor_String_t PROGMEM LanguageString =\r
-{\r
-       .Header                 = {.Size = USB_STRING_LEN(1), .Type = DTYPE_String},\r
-               \r
-       .UnicodeString          = {LANGUAGE_ID_ENG}\r
-};\r
-\r
-/** Manufacturer descriptor string. This is a Unicode string containing the manufacturer's details in human readable\r
- *  form, and is read out upon request by the host when the appropriate string ID is requested, listed in the Device\r
- *  Descriptor.\r
- */\r
-USB_Descriptor_String_t PROGMEM ManufacturerString =\r
-{\r
-       .Header                 = {.Size = USB_STRING_LEN(11), .Type = DTYPE_String},\r
-               \r
-       .UnicodeString          = L"Dean Camera"\r
-};\r
-\r
-/** Product descriptor string. This is a Unicode string containing the product's details in human readable form,\r
- *  and is read out upon request by the host when the appropriate string ID is requested, listed in the Device\r
- *  Descriptor.\r
- */\r
-USB_Descriptor_String_t PROGMEM ProductString =\r
-{\r
-       .Header                 = {.Size = USB_STRING_LEN(18), .Type = DTYPE_String},\r
-               \r
-       .UnicodeString          = L"LUFA Audio In Demo"\r
-};\r
-\r
-/** This function is called by the library when in device mode, and must be overridden (see library "USB Descriptors"\r
- *  documentation) by the application code so that the address and size of a requested descriptor can be given\r
- *  to the USB library. When the device receives a Get Descriptor request on the control endpoint, this function\r
- *  is called so that the descriptor details can be passed back and the appropriate descriptor sent back to the\r
- *  USB host.\r
- */\r
-uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue, const uint8_t wIndex, void** const DescriptorAddress)\r
-{\r
-       const uint8_t  DescriptorType   = (wValue >> 8);\r
-       const uint8_t  DescriptorNumber = (wValue & 0xFF);\r
-\r
-       void*    Address = NULL;\r
-       uint16_t Size    = NO_DESCRIPTOR;\r
-\r
-       switch (DescriptorType)\r
-       {\r
-               case DTYPE_Device:\r
-                       Address = (void*)&DeviceDescriptor;\r
-                       Size    = sizeof(USB_Descriptor_Device_t);\r
-                       break;\r
-               case DTYPE_Configuration: \r
-                       Address = (void*)&ConfigurationDescriptor;\r
-                       Size    = sizeof(USB_Descriptor_Configuration_t);\r
-                       break;\r
-               case DTYPE_String: \r
-                       switch (DescriptorNumber)\r
-                       {\r
-                               case 0x00: \r
-                                       Address = (void*)&LanguageString;\r
-                                       Size    = pgm_read_byte(&LanguageString.Header.Size);\r
-                                       break;\r
-                               case 0x01: \r
-                                       Address = (void*)&ManufacturerString;\r
-                                       Size    = pgm_read_byte(&ManufacturerString.Header.Size);\r
-                                       break;\r
-                               case 0x02: \r
-                                       Address = (void*)&ProductString;\r
-                                       Size    = pgm_read_byte(&ProductString.Header.Size);\r
-                                       break;\r
-                       }\r
-                       \r
-                       break;\r
-       }\r
-       \r
-       *DescriptorAddress = Address;\r
-       return Size;\r
-}\r
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2019.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2019  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  USB Device Descriptors, for library use when in USB device mode. Descriptors are special
+ *  computer-readable structures which the host requests upon device enumeration, to determine
+ *  the device's capabilities and functions.
+ */
+
+#include "Descriptors.h"
+
+/** Device descriptor structure. This descriptor, located in FLASH memory, describes the overall
+ *  device characteristics, including the supported USB version, control endpoint size and the
+ *  number of device configurations. The descriptor is read out by the USB host when the enumeration
+ *  process begins.
+ */
+const USB_Descriptor_Device_t PROGMEM DeviceDescriptor =
+{
+       .Header                 = {.Size = sizeof(USB_Descriptor_Device_t), .Type = DTYPE_Device},
+
+       .USBSpecification       = VERSION_BCD(1,1,0),
+       .Class                  = USB_CSCP_NoDeviceClass,
+       .SubClass               = USB_CSCP_NoDeviceSubclass,
+       .Protocol               = USB_CSCP_NoDeviceProtocol,
+
+       .Endpoint0Size          = FIXED_CONTROL_ENDPOINT_SIZE,
+
+       .VendorID               = 0x03EB,
+       .ProductID              = 0x2047,
+       .ReleaseNumber          = VERSION_BCD(0,0,2),
+
+       .ManufacturerStrIndex   = STRING_ID_Manufacturer,
+       .ProductStrIndex        = STRING_ID_Product,
+       .SerialNumStrIndex      = NO_DESCRIPTOR,
+
+       .NumberOfConfigurations = FIXED_NUM_CONFIGURATIONS
+};
+
+/** Configuration descriptor structure. This descriptor, located in FLASH memory, describes the usage
+ *  of the device in one of its supported configurations, including information about any device interfaces
+ *  and endpoints. The descriptor is read out by the USB host during the enumeration process when selecting
+ *  a configuration so that the host may correctly communicate with the USB device.
+ */
+const USB_Descriptor_Configuration_t PROGMEM ConfigurationDescriptor =
+{
+       .Config =
+               {
+                       .Header                   = {.Size = sizeof(USB_Descriptor_Configuration_Header_t), .Type = DTYPE_Configuration},
+
+                       .TotalConfigurationSize   = sizeof(USB_Descriptor_Configuration_t),
+                       .TotalInterfaces          = 2,
+
+                       .ConfigurationNumber      = 1,
+                       .ConfigurationStrIndex    = NO_DESCRIPTOR,
+
+                       .ConfigAttributes         = (USB_CONFIG_ATTR_RESERVED | USB_CONFIG_ATTR_SELFPOWERED),
+
+                       .MaxPowerConsumption      = USB_CONFIG_POWER_MA(100)
+               },
+
+       .Audio_ControlInterface =
+               {
+                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+                       .InterfaceNumber          = INTERFACE_ID_AudioControl,
+                       .AlternateSetting         = 0,
+
+                       .TotalEndpoints           = 0,
+
+                       .Class                    = AUDIO_CSCP_AudioClass,
+                       .SubClass                 = AUDIO_CSCP_ControlSubclass,
+                       .Protocol                 = AUDIO_CSCP_ControlProtocol,
+
+                       .InterfaceStrIndex        = NO_DESCRIPTOR
+               },
+
+       .Audio_ControlInterface_SPC =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_Interface_AC_t), .Type = AUDIO_DTYPE_CSInterface},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSInterface_Header,
+
+                       .ACSpecification          = VERSION_BCD(1,0,0),
+                       .TotalLength              = (sizeof(USB_Audio_Descriptor_Interface_AC_t) +
+                                                    sizeof(USB_Audio_Descriptor_InputTerminal_t) +
+                                                    sizeof(USB_Audio_Descriptor_OutputTerminal_t)),
+
+                       .InCollection             = 1,
+                       .InterfaceNumber          = INTERFACE_ID_AudioStream,
+               },
+
+       .Audio_InputTerminal =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_InputTerminal_t), .Type = AUDIO_DTYPE_CSInterface},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSInterface_InputTerminal,
+
+                       .TerminalID               = 0x01,
+                       .TerminalType             = AUDIO_TERMINAL_IN_MIC,
+                       .AssociatedOutputTerminal = 0x00,
+
+                       .TotalChannels            = 1,
+                       .ChannelConfig            = 0,
+
+                       .ChannelStrIndex          = NO_DESCRIPTOR,
+                       .TerminalStrIndex         = NO_DESCRIPTOR
+               },
+
+       .Audio_OutputTerminal =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_OutputTerminal_t), .Type = AUDIO_DTYPE_CSInterface},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSInterface_OutputTerminal,
+
+                       .TerminalID               = 0x02,
+                       .TerminalType             = AUDIO_TERMINAL_STREAMING,
+                       .AssociatedInputTerminal  = 0x00,
+
+                       .SourceID                 = 0x01,
+
+                       .TerminalStrIndex         = NO_DESCRIPTOR
+               },
+
+       .Audio_StreamInterface_Alt0 =
+               {
+                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+                       .InterfaceNumber          = INTERFACE_ID_AudioStream,
+                       .AlternateSetting         = 0,
+
+                       .TotalEndpoints           = 0,
+
+                       .Class                    = AUDIO_CSCP_AudioClass,
+                       .SubClass                 = AUDIO_CSCP_AudioStreamingSubclass,
+                       .Protocol                 = AUDIO_CSCP_StreamingProtocol,
+
+                       .InterfaceStrIndex        = NO_DESCRIPTOR
+               },
+
+       .Audio_StreamInterface_Alt1 =
+               {
+                       .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+                       .InterfaceNumber          = INTERFACE_ID_AudioStream,
+                       .AlternateSetting         = 1,
+
+                       .TotalEndpoints           = 1,
+
+                       .Class                    = AUDIO_CSCP_AudioClass,
+                       .SubClass                 = AUDIO_CSCP_AudioStreamingSubclass,
+                       .Protocol                 = AUDIO_CSCP_StreamingProtocol,
+
+                       .InterfaceStrIndex        = NO_DESCRIPTOR
+               },
+
+       .Audio_StreamInterface_SPC =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_Interface_AS_t), .Type = AUDIO_DTYPE_CSInterface},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSInterface_General,
+
+                       .TerminalLink             = 0x02,
+
+                       .FrameDelay               = 1,
+                       .AudioFormat              = 0x0001
+               },
+
+       .Audio_AudioFormat =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_Format_t) +
+                                                            sizeof(ConfigurationDescriptor.Audio_AudioFormatSampleRates),
+                                                    .Type = AUDIO_DTYPE_CSInterface},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSInterface_FormatType,
+
+                       .FormatType               = 0x01,
+                       .Channels                 = 0x01,
+
+                       .SubFrameSize             = 0x02,
+                       .BitResolution            = 16,
+
+                       .TotalDiscreteSampleRates = (sizeof(ConfigurationDescriptor.Audio_AudioFormatSampleRates) / sizeof(USB_Audio_SampleFreq_t)),
+               },
+
+       .Audio_AudioFormatSampleRates =
+               {
+                       AUDIO_SAMPLE_FREQ(8000),
+                       AUDIO_SAMPLE_FREQ(11025),
+                       AUDIO_SAMPLE_FREQ(22050),
+                       AUDIO_SAMPLE_FREQ(44100),
+                       AUDIO_SAMPLE_FREQ(48000),
+               },
+
+       .Audio_StreamEndpoint =
+               {
+                       .Endpoint =
+                               {
+                                       .Header              = {.Size = sizeof(USB_Audio_Descriptor_StreamEndpoint_Std_t), .Type = DTYPE_Endpoint},
+
+                                       .EndpointAddress     = AUDIO_STREAM_EPADDR,
+                                       .Attributes          = (EP_TYPE_ISOCHRONOUS | ENDPOINT_ATTR_SYNC | ENDPOINT_USAGE_DATA),
+                                       .EndpointSize        = AUDIO_STREAM_EPSIZE,
+                                       .PollingIntervalMS   = 0x01
+                               },
+
+                       .Refresh                  = 0,
+                       .SyncEndpointNumber       = 0
+               },
+
+       .Audio_StreamEndpoint_SPC =
+               {
+                       .Header                   = {.Size = sizeof(USB_Audio_Descriptor_StreamEndpoint_Spc_t), .Type = AUDIO_DTYPE_CSEndpoint},
+                       .Subtype                  = AUDIO_DSUBTYPE_CSEndpoint_General,
+
+                       .Attributes               = (AUDIO_EP_ACCEPTS_SMALL_PACKETS | AUDIO_EP_SAMPLE_FREQ_CONTROL),
+
+                       .LockDelayUnits           = 0x00,
+                       .LockDelay                = 0x0000
+               }
+};
+
+/** Language descriptor structure. This descriptor, located in FLASH memory, is returned when the host requests
+ *  the string descriptor with index 0 (the first index). It is actually an array of 16-bit integers, which indicate
+ *  via the language ID table available at USB.org what languages the device supports for its string descriptors.
+ */
+const USB_Descriptor_String_t PROGMEM LanguageString = USB_STRING_DESCRIPTOR_ARRAY(LANGUAGE_ID_ENG);
+
+/** Manufacturer descriptor string. This is a Unicode string containing the manufacturer's details in human readable
+ *  form, and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
+ *  Descriptor.
+ */
+const USB_Descriptor_String_t PROGMEM ManufacturerString = USB_STRING_DESCRIPTOR(L"LUFA Library");
+
+/** Product descriptor string. This is a Unicode string containing the product's details in human readable form,
+ *  and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
+ *  Descriptor.
+ */
+const USB_Descriptor_String_t PROGMEM ProductString = USB_STRING_DESCRIPTOR(L"LUFA Audio In Demo");
+
+/** This function is called by the library when in device mode, and must be overridden (see library "USB Descriptors"
+ *  documentation) by the application code so that the address and size of a requested descriptor can be given
+ *  to the USB library. When the device receives a Get Descriptor request on the control endpoint, this function
+ *  is called so that the descriptor details can be passed back and the appropriate descriptor sent back to the
+ *  USB host.
+ */
+uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
+                                    const uint16_t wIndex,
+                                    const void** const DescriptorAddress)
+{
+       const uint8_t  DescriptorType   = (wValue >> 8);
+       const uint8_t  DescriptorNumber = (wValue & 0xFF);
+
+       const void* Address = NULL;
+       uint16_t    Size    = NO_DESCRIPTOR;
+
+       switch (DescriptorType)
+       {
+               case DTYPE_Device:
+                       Address = &DeviceDescriptor;
+                       Size    = sizeof(USB_Descriptor_Device_t);
+                       break;
+               case DTYPE_Configuration:
+                       Address = &ConfigurationDescriptor;
+                       Size    = sizeof(USB_Descriptor_Configuration_t);
+                       break;
+               case DTYPE_String:
+                       switch (DescriptorNumber)
+                       {
+                               case STRING_ID_Language:
+                                       Address = &LanguageString;
+                                       Size    = pgm_read_byte(&LanguageString.Header.Size);
+                                       break;
+                               case STRING_ID_Manufacturer:
+                                       Address = &ManufacturerString;
+                                       Size    = pgm_read_byte(&ManufacturerString.Header.Size);
+                                       break;
+                               case STRING_ID_Product:
+                                       Address = &ProductString;
+                                       Size    = pgm_read_byte(&ProductString.Header.Size);
+                                       break;
+                       }
+
+                       break;
+       }
+
+       *DescriptorAddress = Address;
+       return Size;
+}
+