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Chapter 5 - Option Management / Option Management Reference

Functions / Finding Options

OTNextOption

Locates the next TOption structure in a buffer.

C INTERFACE

OSErr OTNextOption (UInt8* buffer, UInt32 buflen, 
                    TOption** prevOptPtr;

C++ INTERFACE

None. C++ applications use the C interface to this function.

PARAMETERS

buffer

A pointer to the buffer containing the option to be found.

buflen

A long specifying the size of the buffer containing the option to be found.

prevOptPtr

A pointer to a pointer to the first or current TOption structure. The first time you call the function, set this parameter to the beginning address of the buffer containing the options to be found. On return, this parameter references the beginning address of the next option

DESCRIPTION

The OTNextOption function allows you to parse through a buffer containing TOption structures describing an endpoint's option values. Within the buffer, TOption structures are aligned to long-word boundaries. This function takes into account this padding when it calculates the beginning address of the next TOption structure and it returns that address in the prevOptPtr parameter.

The first time you call the option, set the prevOptPtr parameter to the beginning address of the buffer. When the function returns, the prevOptPtr parameter points to the next (second) option in the buffer. You can continue this process, specifying the value returned for the prevOptPtr parameter by the previous invocation of the function, each time you call the function to obtain the beginning address of each option in the buffer.

SEE ALSO

To find a particular option in a buffer, use the OTFindOption function (page 5-43).