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Inside Macintosh: Mac OS Runtime Architectures /

Appendix B - The RTLib.o and NuRTLib.o Libraries / Runtime Operations

kRTGetJTAddress and kRTGetJTAddressA5

The operation kRTGetJTAddress returns the address of the code that the specified function address points to in the current A5, and kRTGetJTAddressA5 does the same for a specified A5 world.

The fRTParams structure (page B-2) used with these operations is as follows:

struct RTGetJTAddrParam {
   void*fJTAddr;
   void*fCodeAddr;
   };
typedef struct RTGetJTAddrParam RTGetJTAddrParam;

• In the classic 68K runtime environment, fJTAddr is a function address. In the CFM-68K runtime environment, fJTAddr is the address of a transition vector.
• fCodeAddr contains the returned code address. If the segment is not loaded, fCodeAddr is set to 0.

The kRTGetJTAddress operation assumes the current A5 world, while RTGetJTAddressA5 lets you specify one in the fA5 field of the RTPB structure (page B-2).