PPC Toolbox Parameter Blocks

PPC Toolbox functions require a pointer to a PPC parameter block. You

must fill out any fields of the parameter block that the specific

PPC Toolbox function requires.

The qLink, csCode, intUse, intUsePtr, and reserved fields of the

PPCParamBlockRec are used internally by the PPC Toolbox. Your application

should not rely on the PPC Toolbox to preserve these fields across calls.

Your application transfers ownership of the PPC Toolbox parameter block

(and any buffers or records pointed to by the PPC Toolbox parameter block)

to the PPC Toolbox until a PPC function is complete. Once the function

completes, ownership of the parameter block (and any buffers or records it

points to) is transferred back to your application. If a PPC Toolbox function

is executed asynchronously, your program cannot alter memory that might be

used by the PPC Toolbox until that function completes.

A PPC Toolbox function that is executed asynchronously must specify NIL or

the address of a completion routine in the ioCompletion field of the

PPC parameter block. The ioResult field should be used to determine the

actual result code when an asynchronously executed PPC Toolbox function

completes.

If you specify a completion routine in the ioCompletion field, it is called at

interrupt time when the PPC Toolbox function completes execution.

Warning: Completion routines execute at the interrupt level and must

preserve all registers other than A0, A1, and D0-D2. (Note that most

commercial high-level languages do this automatically.) Your completion

routine must not make any calls to the Memory Manager, directly or

indirectly, and it can't depend on the validity of handles to unlocked blocks. The

PPC Toolbox pre serves the application global register A5.

You can write completion routines in C, Pascal, or assembly language. A

completion routine declared in Think C is:

pascal void MyCompletionRoutine (PPCParamBlockPtr Pb);

The pb parameter points to the PPC parameter block passed to the