Card Information Structures
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8/28/2008
A Secure Digital (SD) I/O (SDIO) card contains one or more card information structures (CIS). An SDIO client driver will need to read from these structures to obtain the capabilities and functionality of the card.
A CIS is organized as a chain of data blocks, also called tuples, containing standard and application-specific information. An SDIO card has a common CIS area for the entire card, and a CIS area for each individual card function. A client driver is able to read from the CIS area of its own function, or from the common CIS area, by using the CommonCIS parameter flag.
The SDGetTuple function allows a client driver to access a specific tuple without having to programatically traverse the tuple chain. Since tuples are often of an unknown size, the function call to SDGetTuple will return the size of the tuple in pBufferSizeif pBufferis set to NULL.
A tuple length of zero indicates that the tuple does not exist. When the tuple length has been determined, the client driver can allocate sufficient memory and call the API again with a non-NULL value for pBufferto read the tuple data.