The cpc_version() function takes an interface version as an argument and returns an interface version as a result. Usually, the argument will be the value of CPC_VER_CURRENT bound to the application when it was compiled.

If the version requested is still supported by the implementation, cpc_version() returns the requested version number and the application can use the facilities of the library on that platform. If the implementation cannot support the version needed by the application, cpc_version() returns CPC_VER_NONE, indicating that the application will at least need to be recompiled to operate correctly on the new platform, and may require further changes.

If version is CPC_VER_NONE, cpc_version() returns the most current version of the library.

See attributes(5) for descriptions of the following attributes:

cpc(3CPC), attributes(5)

The version number is used only to express incompatible semantic changes in the performance counter interfaces on the given platform within a single instruction set architecture, for example, when a new set of performance counter registers are added to an existing processor family that cannot be specified in the existing cpc_event_t data structure.