LUFA Library  210130
Configuration Descriptor Parser

USB Configuration Descriptor definitions. More...

Macros

#define DESCRIPTOR_CAST(DescriptorPtr, Type)   (*DESCRIPTOR_PCAST(DescriptorPtr, Type))
 
#define DESCRIPTOR_PCAST(DescriptorPtr, Type)   ((Type*)(DescriptorPtr))
 
#define DESCRIPTOR_SIZE(DescriptorPtr)   DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Size
 
#define DESCRIPTOR_TYPE(DescriptorPtr)   DESCRIPTOR_PCAST(DescriptorPtr, USB_Descriptor_Header_t)->Type
 

Typedefs

typedef uint8_t(* ConfigComparatorPtr_t) (void *)
 

Enumerations

enum  DSearch_Comp_Return_ErrorCodes_t {
  DESCRIPTOR_SEARCH_COMP_Found = 0 ,
  DESCRIPTOR_SEARCH_COMP_Fail = 1 ,
  DESCRIPTOR_SEARCH_COMP_EndOfDescriptor = 2
}
 
enum  DSearch_Return_ErrorCodes_t {
  DESCRIPTOR_SEARCH_Found = 0 ,
  DESCRIPTOR_SEARCH_Fail = 1 ,
  DESCRIPTOR_SEARCH_NotFound = 2
}
 
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
}
 

Functions

static void USB_GetNextDescriptor (uint16_t *const BytesRem, void **CurrConfigLoc) 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) ATTR_NON_NULL_PTR_ARG(1) 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_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)
 
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)
 
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)
 

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.

Macro Definition Documentation

◆ DESCRIPTOR_CAST

#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
// Can now access elements of the configuration header struct using the . operator
#define DESCRIPTOR_CAST(DescriptorPtr, Type)
Definition: ConfigDescriptors.h:97
Standard USB Configuration Descriptor (LUFA naming conventions).
Definition: StdDescriptors.h:462

◆ DESCRIPTOR_PCAST

#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,
// Can now access elements of the configuration header struct using the -> indirection operator
#define DESCRIPTOR_PCAST(DescriptorPtr, Type)
Definition: ConfigDescriptors.h:83

◆ DESCRIPTOR_SIZE

#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.

◆ DESCRIPTOR_TYPE

#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

◆ ConfigComparatorPtr_t

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

◆ 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.

◆ 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.

◆ 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

◆ USB_GetNextDescriptor()

static void USB_GetNextDescriptor ( uint16_t *const  BytesRem,
void **  CurrConfigLoc 
)
inlinestatic

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]BytesRemPointer to the number of bytes remaining of the configuration descriptor.
[in,out]CurrConfigLocPointer to the current descriptor inside the configuration descriptor.

◆ USB_GetNextDescriptorComp()

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 behavior 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]BytesRemPointer to an int storing the remaining bytes in the configuration descriptor.
[in,out]CurrConfigLocPointer to the current position in the configuration descriptor.
[in]ComparatorRoutineName 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)
else
}
//...
// After retrieving configuration descriptor:
if (USB_Host_GetNextDescriptorComp(&BytesRemaining, &CurrentConfigLoc, EndpointSearcher) ==
Descriptor_Search_Comp_Found)
{
// Do something with the endpoint descriptor
}
#define DESCRIPTOR_TYPE(DescriptorPtr)
Definition: ConfigDescriptors.h:103
@ DESCRIPTOR_SEARCH_Found
Definition: ConfigDescriptors.h:138
@ DESCRIPTOR_SEARCH_NotFound
Definition: ConfigDescriptors.h:140
@ DTYPE_Endpoint
Definition: StdDescriptors.h:213

◆ USB_GetNextDescriptorOfType()

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]BytesRemPointer to the number of bytes remaining of the configuration descriptor.
[in,out]CurrConfigLocPointer to the current descriptor inside the configuration descriptor.
[in]TypeDescriptor type value to search for.

◆ USB_GetNextDescriptorOfTypeAfter()

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]BytesRemPointer to the number of bytes remaining of the configuration descriptor.
[in,out]CurrConfigLocPointer to the current descriptor inside the configuration descriptor.
[in]TypeDescriptor type value to search for.
[in]AfterTypeDescriptor type value which must be reached before the given Type descriptor.

◆ USB_GetNextDescriptorOfTypeBefore()

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]BytesRemPointer to the number of bytes remaining of the configuration descriptor.
[in,out]CurrConfigLocPointer to the current descriptor inside the configuration descriptor.
[in]TypeDescriptor type value to search for.
[in]BeforeTypeDescriptor type value which must not be reached before the given Type descriptor.

◆ USB_Host_GetDeviceConfigDescriptor()

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]ConfigNumberDevice configuration descriptor number to fetch from the device (usually set to 1 for single configuration devices).
[in,out]ConfigSizePtrPointer to a location for storing the retrieved configuration descriptor size.
[out]BufferPtrPointer to the buffer for storing the configuration descriptor data.
[out]BufferSizeSize of the allocated buffer where the configuration descriptor is to be stored.
Returns
A value from the USB_Host_GetConfigDescriptor_ErrorCodes_t enum.