USB Configuration Descriptor definitions. More...

Defines
#define	DESCRIPTOR_PCAST(DescriptorPtr, Type) ((Type*)(DescriptorPtr))
#define	DESCRIPTOR_CAST(DescriptorPtr, Type) (*DESCRIPTOR_PCAST(DescriptorPtr, Type))
#define	DESCRIPTOR_TYPE(DescriptorPtr) DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Type
#define	DESCRIPTOR_SIZE(DescriptorPtr) DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Size
Typedefs
typedef uint8_t(*	ConfigComparatorPtr_t )(void *)
Enumerations
enum	USB_Host_GetConfigDescriptor_ErrorCodes_t { HOST_GETCONFIG_Successful = 0, HOST_GETCONFIG_DeviceDisconnect = 1, HOST_GETCONFIG_PipeError = 2, HOST_GETCONFIG_SetupStalled = 3, HOST_GETCONFIG_SoftwareTimeOut = 4, HOST_GETCONFIG_BuffOverflow = 5, HOST_GETCONFIG_InvalidData = 6 }
enum	DSearch_Return_ErrorCodes_t { DESCRIPTOR_SEARCH_Found = 0, DESCRIPTOR_SEARCH_Fail = 1, DESCRIPTOR_SEARCH_NotFound = 2 }
enum	DSearch_Comp_Return_ErrorCodes_t { DESCRIPTOR_SEARCH_COMP_Found = 0, DESCRIPTOR_SEARCH_COMP_Fail = 1, DESCRIPTOR_SEARCH_COMP_EndOfDescriptor = 2 }
Functions
uint8_t	USB_Host_GetDeviceConfigDescriptor (const uint8_t ConfigNumber, uint16_t const ConfigSizePtr, void const BufferPtr, const uint16_t BufferSize) ATTR_NON_NULL_PTR_ARG(2) ATTR_NON_NULL_PTR_ARG(3)
void	USB_GetNextDescriptorOfType (uint16_t const BytesRem, void *const CurrConfigLoc, const uint8_t Type) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
void	USB_GetNextDescriptorOfTypeBefore (uint16_t const BytesRem, void *const CurrConfigLoc, const uint8_t Type, const uint8_t BeforeType) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
void	USB_GetNextDescriptorOfTypeAfter (uint16_t const BytesRem, void *const CurrConfigLoc, const uint8_t Type, const uint8_t AfterType) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
uint8_t	USB_GetNextDescriptorComp (uint16_t const BytesRem, void *const CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine)
static void	USB_GetNextDescriptor (uint16_t const BytesRem, void *CurrConfigLoc) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)

Detailed Description

This section of the library gives a friendly API which can be used in host applications to easily parse an attached device's configuration descriptor so that endpoint, interface and other descriptor data can be extracted and used as needed.

Define Documentation

#define DESCRIPTOR_CAST	(	DescriptorPtr,
		Type
	)	(*DESCRIPTOR_PCAST(DescriptorPtr, Type))

Casts a pointer to a descriptor inside the configuration descriptor into the given descriptor type (as an actual struct instance rather than a pointer to a struct).

Usage Example:

  uint8_t* CurrDescriptor = &ConfigDescriptor[0]; // Pointing to the configuration header
  USB_Descriptor_Configuration_Header_t ConfigHeader = DESCRIPTOR_CAST(CurrDescriptor,
                                                       USB_Descriptor_Configuration_Header_t);

  // Can now access elements of the configuration header struct using the . operator

#define DESCRIPTOR_PCAST	(	DescriptorPtr,
		Type
	)	((Type*)(DescriptorPtr))

Casts a pointer to a descriptor inside the configuration descriptor into a pointer to the given descriptor type.

Usage Example:

  uint8_t* CurrDescriptor = &ConfigDescriptor[0]; // Pointing to the configuration header
  USB_Descriptor_Configuration_Header_t* ConfigHeaderPtr = DESCRIPTOR_PCAST(CurrDescriptor,
                                                           USB_Descriptor_Configuration_Header_t);

  // Can now access elements of the configuration header struct using the -> indirection operator

#define DESCRIPTOR_SIZE ( DescriptorPtr ) DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Size

Returns the descriptor's size, expressed as the 8-bit value indicating the number of bytes.

#define DESCRIPTOR_TYPE ( DescriptorPtr ) DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Type

Returns the descriptor's type, expressed as the 8-bit type value in the header of the descriptor. This value's meaning depends on the descriptor's placement in the descriptor, but standard type values can be accessed in the USB_DescriptorTypes_t enum.

Typedef Documentation

typedef uint8_t(* ConfigComparatorPtr_t)(void *)

Type define for a Configuration Descriptor comparator function (function taking a pointer to an array of type void, returning a uint8_t value).

See also:: USB_GetNextDescriptorComp function for more details.

Enumeration Type Documentation

enum DSearch_Comp_Return_ErrorCodes_t

Enum for return values of USB_GetNextDescriptorComp().

Enumerator:

DESCRIPTOR_SEARCH_COMP_Found	Configuration descriptor now points to descriptor which matches search criteria of the given comparator function.
DESCRIPTOR_SEARCH_COMP_Fail	Comparator function returned DESCRIPTOR_SEARCH_Fail.
DESCRIPTOR_SEARCH_COMP_EndOfDescriptor	End of configuration descriptor reached before match found.

enum DSearch_Return_ErrorCodes_t

Enum for return values of a descriptor comparator function.

Enumerator:

DESCRIPTOR_SEARCH_Found	Current descriptor matches comparator criteria.
DESCRIPTOR_SEARCH_Fail	No further descriptor could possibly match criteria, fail the search.
DESCRIPTOR_SEARCH_NotFound	Current descriptor does not match comparator criteria.

enum USB_Host_GetConfigDescriptor_ErrorCodes_t

Enum for the possible return codes of the USB_Host_GetDeviceConfigDescriptor() function.

Enumerator:

HOST_GETCONFIG_Successful	No error occurred while retrieving the configuration descriptor.
HOST_GETCONFIG_DeviceDisconnect	The attached device was disconnected while retrieving the configuration descriptor.
HOST_GETCONFIG_PipeError	An error occurred in the pipe while sending the request.
HOST_GETCONFIG_SetupStalled	The attached device stalled the request to retrieve the configuration descriptor.
HOST_GETCONFIG_SoftwareTimeOut	The request or data transfer timed out.
HOST_GETCONFIG_BuffOverflow	The device's configuration descriptor is too large to fit into the allocated buffer.
HOST_GETCONFIG_InvalidData	The device returned invalid configuration descriptor data.

Function Documentation

static void USB_GetNextDescriptor	(	uint16_t *const	BytesRem,
		void **	CurrConfigLoc
	)		`[inline, static]`

Skips over the current sub-descriptor inside the configuration descriptor, so that the pointer then points to the next sub-descriptor. The bytes remaining value is automatically decremented.

Parameters:

[in,out]	BytesRem	Pointer to the number of bytes remaining of the configuration descriptor.
[in,out]	CurrConfigLoc	Pointer to the current descriptor inside the configuration descriptor.

uint8_t USB_GetNextDescriptorComp	(	uint16_t *const	BytesRem,
		void **const	CurrConfigLoc,
		ConfigComparatorPtr_t const	ComparatorRoutine
	)

Searches for the next descriptor in the given configuration descriptor using a pre-made comparator function. The routine updates the position and remaining configuration descriptor bytes values automatically. If a comparator routine fails a search, the descriptor pointer is retreated back so that the next descriptor search invocation will start from the descriptor which first caused the original search to fail. This behaviour allows for one comparator to be used immediately after another has failed, starting the second search from the descriptor which failed the first.

Comparator functions should be standard functions which accept a pointer to the header of the current descriptor inside the configuration descriptor which is being compared, and should return a value from the DSearch_Return_ErrorCodes_t enum as a uint8_t value.

Note:: This function is available in USB Host mode only.

Parameters:

[in,out]	BytesRem	Pointer to an int storing the remaining bytes in the configuration descriptor.
[in,out]	CurrConfigLoc	Pointer to the current position in the configuration descriptor.
[in]	ComparatorRoutine	Name of the comparator search function to use on the configuration descriptor.

Returns:: Value of one of the members of the DSearch_Comp_Return_ErrorCodes_t enum.

Usage Example:

  uint8_t EndpointSearcher(void* CurrentDescriptor); // Comparator Prototype

  uint8_t EndpointSearcher(void* CurrentDescriptor)
  {
     if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
         return DESCRIPTOR_SEARCH_Found;
     else
         return DESCRIPTOR_SEARCH_NotFound;
  }

  //...
  // After retrieving configuration descriptor:
  if (USB_Host_GetNextDescriptorComp(&BytesRemaining, &CurrentConfigLoc, EndpointSearcher) ==
      Descriptor_Search_Comp_Found)
  {
      // Do something with the endpoint descriptor
  }

void USB_GetNextDescriptorOfType	(	uint16_t *const	BytesRem,
		void **const	CurrConfigLoc,
		const uint8_t	Type
	)

Skips to the next sub-descriptor inside the configuration descriptor of the specified type value. The bytes remaining value is automatically decremented.

Parameters:

[in,out]	BytesRem	Pointer to the number of bytes remaining of the configuration descriptor.
[in,out]	CurrConfigLoc	Pointer to the current descriptor inside the configuration descriptor.
[in]	Type	Descriptor type value to search for.

void USB_GetNextDescriptorOfTypeAfter	(	uint16_t *const	BytesRem,
		void **const	CurrConfigLoc,
		const uint8_t	Type,
		const uint8_t	AfterType
	)

Skips to the next sub-descriptor inside the configuration descriptor of the specified type value, which must come after a descriptor of the second given type value. The bytes remaining value is automatically decremented.

Parameters:

[in,out]	BytesRem	Pointer to the number of bytes remaining of the configuration descriptor.
[in,out]	CurrConfigLoc	Pointer to the current descriptor inside the configuration descriptor.
[in]	Type	Descriptor type value to search for.
[in]	AfterType	Descriptor type value which must be reached before the given Type descriptor.

void USB_GetNextDescriptorOfTypeBefore	(	uint16_t *const	BytesRem,
		void **const	CurrConfigLoc,
		const uint8_t	Type,
		const uint8_t	BeforeType
	)

Skips to the next sub-descriptor inside the configuration descriptor of the specified type value, which must come before a descriptor of the second given type value. If the BeforeType type descriptor is reached first, the number of bytes remaining to process is set to zero and the function exits. The bytes remaining value is automatically decremented.

Parameters:

[in,out]	BytesRem	Pointer to the number of bytes remaining of the configuration descriptor.
[in,out]	CurrConfigLoc	Pointer to the current descriptor inside the configuration descriptor.
[in]	Type	Descriptor type value to search for.
[in]	BeforeType	Descriptor type value which must not be reached before the given Type descriptor.

uint8_t USB_Host_GetDeviceConfigDescriptor	(	const uint8_t	ConfigNumber,
		uint16_t *const	ConfigSizePtr,
		void *const	BufferPtr,
		const uint16_t	BufferSize
	)

Retrieves the configuration descriptor data from an attached device via a standard request into a buffer, including validity and size checking to prevent a buffer overflow.

Parameters:

[in]	ConfigNumber	Device configuration descriptor number to fetch from the device (usually set to 1 for single configuration devices).
[in,out]	ConfigSizePtr	Pointer to a location for storing the retrieved configuration descriptor size.
[out]	BufferPtr	Pointer to the buffer for storing the configuration descriptor data.
[out]	BufferSize	Size of the allocated buffer where the configuration descriptor is to be stored.

Returns:: A value from the USB_Host_GetConfigDescriptor_ErrorCodes_t enum.

Defines

Typedefs

Enumerations

Functions

Detailed Description

Define Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation