Commit f606afef authored by Dean Camera's avatar Dean Camera
Browse files

Remove void* arithmetic in the USB_GetNextDescriptor() static inline function,...

Remove void* arithmetic in the USB_GetNextDescriptor() static inline function, to make the header file C++ compatible once again. Implement workaround for an obscure GCC bug which can cause incorrect code generation under some circumstances when the void* is re-cast.
parent 152b2764
......@@ -114,13 +114,13 @@ void USB_GetNextDescriptorOfTypeAfter(uint16_t* const BytesRem,
USB_GetNextDescriptorOfType(BytesRem, CurrConfigLoc, Type);
}
uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine)
uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** const CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine)
{
uint8_t ErrorCode;
while (*BytesRem)
{
void* PrevDescLoc = *CurrConfigLoc;
uint8_t* PrevDescLoc = *CurrConfigLoc;
uint16_t PrevBytesRem = *BytesRem;
USB_GetNextDescriptor(BytesRem, CurrConfigLoc);
......
......@@ -119,49 +119,6 @@
* \see \ref USB_GetNextDescriptorComp function for more details
*/
typedef uint8_t (* ConfigComparatorPtr_t)(void*);
/* Function Prototypes: */
/** Searches for the next descriptor in the given configuration descriptor using a premade 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 \ref DSearch_Return_ErrorCodes_t enum as a uint8_t value.
*
* \note This function is available in USB Host mode only.
*
* \param[in,out] BytesRem Pointer to an int storing the remaining bytes in the configuration descriptor
* \param[in,out] CurrConfigLoc Pointer to the current position in the configuration descriptor
* \param[in] ComparatorRoutine Name of the comparator search function to use on the configuration descriptor
*
* \return Value of one of the members of the \ref DSearch_Comp_Return_ErrorCodes_t enum
*
* Usage Example:
* \code
* 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
* }
* \endcode
*/
uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine);
/* Enums: */
/** Enum for the possible return codes of the \ref USB_Host_GetDeviceConfigDescriptor() function. */
......@@ -257,7 +214,59 @@
const uint8_t AfterType)
ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2);
/** Searches for the next descriptor in the given configuration descriptor using a premade 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 \ref DSearch_Return_ErrorCodes_t enum as a uint8_t value.
*
* \note This function is available in USB Host mode only.
*
* \param[in,out] BytesRem Pointer to an int storing the remaining bytes in the configuration descriptor
* \param[in,out] CurrConfigLoc Pointer to the current position in the configuration descriptor
* \param[in] ComparatorRoutine Name of the comparator search function to use on the configuration descriptor
*
* \return Value of one of the members of the \ref DSearch_Comp_Return_ErrorCodes_t enum
*
* Usage Example:
* \code
* 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
* }
* \endcode
*/
uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** const CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine);
/* Inline Functions: */
#if !defined(__DOXYGEN__)
static inline void USB_GetNextDescriptorST(uint16_t* const BytesRem, uint8_t** CurrConfigLoc)
{
uint16_t CurrDescriptorSize = DESCRIPTOR_CAST(*CurrConfigLoc, USB_Descriptor_Header_t).Size;
*CurrConfigLoc += CurrDescriptorSize;
*BytesRem -= CurrDescriptorSize;
}
#endif
/** 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.
*
......@@ -268,12 +277,14 @@
ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2);
static inline void USB_GetNextDescriptor(uint16_t* const BytesRem, void** CurrConfigLoc)
{
uint16_t CurrDescriptorSize = DESCRIPTOR_CAST(*CurrConfigLoc, USB_Descriptor_Header_t).Size;
*CurrConfigLoc += CurrDescriptorSize;
*BytesRem -= CurrDescriptorSize;
/* Horrible workaround for a bug in GCC - in some circumstances, the code generated for the strongly-typed
* (uint8_t**) cast to avoid void pointer arithmetic (which is not allowed in C++) causes incorrect code to
* be generated. Performing the cast and using a secondary inline routine show here seems to avoid the
* problem.
*/
USB_GetNextDescriptorST(BytesRem, (uint8_t**)CurrConfigLoc);
}
/* Disable C linkage for C++ Compilers: */
#if defined(__cplusplus)
}
......
......@@ -21,7 +21,7 @@
* - AT90USB162 Breadboard PCB (Russian): http://microsin.ru/content/view/685/44/
* - Benito #7, a no-frills USB board: http://www.dorkbotpdx.org/wiki/benito
* - Bumble-B, yet another AT90USB162 development board: http://fletchtronics.net/bumble-b
* - JM-DB-U2, an ATMEGA32U2 development board: http://u2.mattair.net/index.html
* - JM-DB-U2, an ATMEGA32U2 development board: http://www.mattairtech.com/index.php/development-boards/atmega32u2-development-board.html
* - Micropendous, an open design/source set of AVR USB development boards: http://micropendous.org/
* - Nanduino, a do-it-yourself AT90USB162 board: http://www.makestuff.eu/wordpress/?page_id=569
* - Teensy and Teensy++, two other AVR USB development boards: http://www.pjrc.com/teensy/index.html
......
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