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Appendix B - The RTLib.o and NuRTLib.o Libraries

Runtime Interface

The RTLib runtime interface consists of a single procedure call (as defined in RTLib.h):

pascal OSErr Runtime (RTPB* runtimeParams);

The RTPB data type is a structure in which you specify one of four posssible parameter blocks:

struct RTPB {
   short fOperation;
   void* fA5;
   union {
      RTGetVersionParam fVersionParam;
      RTGetJTAddrParam fJTAddrParam;
      RTSetSegLoadParam fSegLoadParam;
      RTLoadSegbyNumParam fLoadbyNumParam;
      } fRTParams;
   };
typedef struct RTPB RTPB;

The fields of the RTPB structure are as follows:

• The fOperation field indicates the type of operation to be performed, and it can be set to any value shown in Table B-1 (page B-3). See "Runtime Operations" (page B-4) for more detailed information.
• Any operation whose name ends in A5 requires a value for the fA5 field, which indicates the address of an A5 world. The similarly named operation without the A5 suffix uses the current value of A5 for this parameter.
• The fRTParams field is a parameter block consisting of one of four structures that hold the parameters for the appropriate operation. See the descriptions for each operation in "Runtime Operations" (page B-4) for more details about these structures.

  Table B-1 Runtime routine operation values

  Value		Description
  kRTSetPreLoad	kRTSetPreLoadA5	Arranges for a user handler to be called by the Segment Manager before loading a segment.
  kRTSetSegLoadErr	kRTSetSegLoadErrA5	Arranges for a user handler to be called if a segment load fails.
  kRTSetPostLoad	kRTSetPostLoadA5	Arranges for a user handler to be called by the Segment Manager immediately after loading a segment.
  kRTSetPreUnload	kRTSetPreUnloadA5	Arranges for a user handler to be called by the Segment Manager before unloading a segment.
  kRTGetVersion	kRTGetVersionA5	Returns version number of A5 world.
  kRTGetJTAddress	kRTGetJTAddressA5	Returns address of the code pointed to by the specified function address.
  kRTPreLaunch		Required if you need to call the _Launch or _Chain routine.
  KRTPostLaunch
  KRTLoadSegbyNum	KRTLoadSegbyNumA5	Loads a segment by segment number (CFM-68K only).

The Runtime routine can return an error value as shown in Table B-2.

Table B-2 Runtime routine error values

Error	Description
eRTNoErr	No error (success)
eRTInvalidOP	Invalid operation
eRTBadVersion	Invalid version
eRTInvalidJTPtr	Invalid jump table pointer
eRT_not_segmented	A5 world not segmented (for example, the A5 world of a CFM-68K shared library)

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© Apple Computer, Inc.
11 MARCH 1997

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