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.
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Dean Camera
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152b2764c3
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3 changed files with 62 additions and 51 deletions
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@ -119,49 +119,6 @@
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* \see \ref USB_GetNextDescriptorComp function for more details
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*/
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typedef uint8_t (* ConfigComparatorPtr_t)(void*);
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/* Function Prototypes: */
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/** Searches for the next descriptor in the given configuration descriptor using a premade comparator
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* function. The routine updates the position and remaining configuration descriptor bytes values
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* automatically. If a comparator routine fails a search, the descriptor pointer is retreated back
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* so that the next descriptor search invocation will start from the descriptor which first caused the
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* original search to fail. This behaviour allows for one comparator to be used immediately after another
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* has failed, starting the second search from the descriptor which failed the first.
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*
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* Comparator functions should be standard functions which accept a pointer to the header of the current
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* descriptor inside the configuration descriptor which is being compared, and should return a value from
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* the \ref DSearch_Return_ErrorCodes_t enum as a uint8_t value.
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*
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* \note This function is available in USB Host mode only.
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*
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* \param[in,out] BytesRem Pointer to an int storing the remaining bytes in the configuration descriptor
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* \param[in,out] CurrConfigLoc Pointer to the current position in the configuration descriptor
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* \param[in] ComparatorRoutine Name of the comparator search function to use on the configuration descriptor
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*
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* \return Value of one of the members of the \ref DSearch_Comp_Return_ErrorCodes_t enum
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*
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* Usage Example:
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* \code
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* uint8_t EndpointSearcher(void* CurrentDescriptor); // Comparator Prototype
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*
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* uint8_t EndpointSearcher(void* CurrentDescriptor)
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* {
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* if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
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* return DESCRIPTOR_SEARCH_Found;
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* else
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* return DESCRIPTOR_SEARCH_NotFound;
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* }
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*
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* //...
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* // After retrieving configuration descriptor:
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* if (USB_Host_GetNextDescriptorComp(&BytesRemaining, &CurrentConfigLoc, EndpointSearcher) ==
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* Descriptor_Search_Comp_Found)
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* {
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* // Do something with the endpoint descriptor
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* }
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* \endcode
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*/
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uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine);
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/* Enums: */
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/** Enum for the possible return codes of the \ref USB_Host_GetDeviceConfigDescriptor() function. */
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@ -257,7 +214,59 @@
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const uint8_t AfterType)
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ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2);
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/** Searches for the next descriptor in the given configuration descriptor using a premade comparator
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* function. The routine updates the position and remaining configuration descriptor bytes values
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* automatically. If a comparator routine fails a search, the descriptor pointer is retreated back
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* so that the next descriptor search invocation will start from the descriptor which first caused the
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* original search to fail. This behaviour allows for one comparator to be used immediately after another
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* has failed, starting the second search from the descriptor which failed the first.
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*
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* Comparator functions should be standard functions which accept a pointer to the header of the current
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* descriptor inside the configuration descriptor which is being compared, and should return a value from
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* the \ref DSearch_Return_ErrorCodes_t enum as a uint8_t value.
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*
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* \note This function is available in USB Host mode only.
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*
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* \param[in,out] BytesRem Pointer to an int storing the remaining bytes in the configuration descriptor
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* \param[in,out] CurrConfigLoc Pointer to the current position in the configuration descriptor
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* \param[in] ComparatorRoutine Name of the comparator search function to use on the configuration descriptor
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*
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* \return Value of one of the members of the \ref DSearch_Comp_Return_ErrorCodes_t enum
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*
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* Usage Example:
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* \code
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* uint8_t EndpointSearcher(void* CurrentDescriptor); // Comparator Prototype
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*
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* uint8_t EndpointSearcher(void* CurrentDescriptor)
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* {
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* if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Endpoint)
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* return DESCRIPTOR_SEARCH_Found;
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* else
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* return DESCRIPTOR_SEARCH_NotFound;
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* }
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*
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* //...
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* // After retrieving configuration descriptor:
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* if (USB_Host_GetNextDescriptorComp(&BytesRemaining, &CurrentConfigLoc, EndpointSearcher) ==
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* Descriptor_Search_Comp_Found)
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* {
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* // Do something with the endpoint descriptor
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* }
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* \endcode
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*/
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uint8_t USB_GetNextDescriptorComp(uint16_t* BytesRem, void** const CurrConfigLoc, ConfigComparatorPtr_t const ComparatorRoutine);
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/* Inline Functions: */
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#if !defined(__DOXYGEN__)
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static inline void USB_GetNextDescriptorST(uint16_t* const BytesRem, uint8_t** CurrConfigLoc)
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{
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uint16_t CurrDescriptorSize = DESCRIPTOR_CAST(*CurrConfigLoc, USB_Descriptor_Header_t).Size;
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*CurrConfigLoc += CurrDescriptorSize;
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*BytesRem -= CurrDescriptorSize;
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}
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#endif
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/** Skips over the current sub-descriptor inside the configuration descriptor, so that the pointer then
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points to the next sub-descriptor. The bytes remaining value is automatically decremented.
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*
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@ -268,12 +277,14 @@
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ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2);
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static inline void USB_GetNextDescriptor(uint16_t* const BytesRem, void** CurrConfigLoc)
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{
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uint16_t CurrDescriptorSize = DESCRIPTOR_CAST(*CurrConfigLoc, USB_Descriptor_Header_t).Size;
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*CurrConfigLoc += CurrDescriptorSize;
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*BytesRem -= CurrDescriptorSize;
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/* Horrible workaround for a bug in GCC - in some circumstances, the code generated for the strongly-typed
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* (uint8_t**) cast to avoid void pointer arithmetic (which is not allowed in C++) causes incorrect code to
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* be generated. Performing the cast and using a secondary inline routine show here seems to avoid the
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* problem.
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*/
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USB_GetNextDescriptorST(BytesRem, (uint8_t**)CurrConfigLoc);
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}
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/* Disable C linkage for C++ Compilers: */
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#if defined(__cplusplus)
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}
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