Q: What is the glue for calling
PBXGetVolInfoSync and PBXGetVolInfoAsync?
A: Here is the glue that you need:
#if GENERATINGCFM
#include <Traps.h>
#include <FSM.h>
// kFSMXGetVolInfo was not introduced until Universal Interfaces 3.0.1.
#if UNIVERSAL_INTERFACES_VERSION < 0x0301
enum {
kFSMXGetVolInfo = 0x0012
};
#endif
// Define the ProcInfoType value for the PBXGetVolInfo routines.
enum {
uppXGetVolInfoProcInfo = kRegisterBased |
RESULT_SIZE(SIZE_CODE(sizeof(OSErr))) |
REGISTER_RESULT_LOCATION(kRegisterD0) |
REGISTER_ROUTINE_PARAMETER(1, kRegisterD0, kFourByteCode) |
REGISTER_ROUTINE_PARAMETER(2, kRegisterD1, kFourByteCode) |
REGISTER_ROUTINE_PARAMETER(3, kRegisterA0, SIZE_CODE(sizeof(XVolumeParamPtr)))
};
// Glue for the sync routine.
extern pascal OSErr PBXGetVolInfoSync(XVolumeParamPtr paramBlock)
{
return CallOSTrapUniversalProc(GetOSTrapAddress(_FSDispatch), uppXGetVolInfoProcInfo,
kFSMXGetVolInfo, // selector in D0
_FSDispatch, // trap word in D1
paramBlock // paramBlock in A0
);
}
// Glue for the async routine.
extern pascal OSErr PBXGetVolInfoAsync(XVolumeParamPtr paramBlock)
{
return CallOSTrapUniversalProc(GetOSTrapAddress(_FSDispatch), uppXGetVolInfoProcInfo,
kFSMXGetVolInfo, // selector in D0
_FSDispatch | kAsyncMask, // trap word in D1
paramBlock // paramBlock in A0
);
}
#endif
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IMPORTANT:
While the glue in this Q&A has always been correct, DTS
has given out incorrect glue for
PBXGetVolInfoSync to a number of individual
developers. This glue appears to work, but there is a
distinct chance it will cause the computer to crash
eventually. If you are using this incorrect glue, you should
update to the glue given above as soon as possible.
You can recognize the incorrect glue by looking at the
ProcInfoType it constructs. The
ProcInfoType construction code for the
incorrect glue is shown below.
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// WARNING: Do not use this code
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#define PROCINFO \
kRegisterBased | \
RESULT_SIZE(SIZE_CODE(sizeof(OSErr))) | \
REGISTER_RESULT_LOCATION(kRegisterD0) | \
REGISTER_ROUTINE_PARAMETER(1, kRegisterD0, kTwoByteCode) | \
REGISTER_ROUTINE_PARAMETER(2, kRegisterA0, SIZE_CODE(sizeof(XVolumeParamPtr)))
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// WARNING: Do not use this code
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This ProcInfoType is incorrect because it
does not describe the use of 68K register D1 as an implicit
parameter to PBXGetVolInfoSync. Register D1
determines whether the trap runs synchronously or
asynchronously. If you fail to set it up, the trap may run
asynchronously (based on the previous contents of register
D1) which, depending on a variety of circumstances, may
crash the computer.
For more information on how to build glue for calling
classic 68K code from CFM, including OS traps like
PBXGetVolInfoSync, read Technote 1127
In Search of Missing
Links.
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