On 30 Sep 2008, at 10:45, EarMaster - Bent Olsen wrote:
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:fpc-pascal-
[EMAIL PROTECTED] On Behalf Of Jonas Maebe
Sent: 29. september 2008 16:26
To: FPC-Pascal users discussions
Subject: Re: [fpc-pascal] Carbon: i386 and PPC API differences
"const inDescription: ComponentDescription" is wrong, because FPC
does
not guarantee that this will be passed by reference (especially in
case of C imports, because in C "const" also means "pass by value").
Either use a pointer type, or use "var" instead. There is no constvar
or similar specifier.
I made a mistake here: when using the "mwpascal" calling convention,
"const" in combination with a record does in fact always mean "pass by
reference", because that's the meaning it also had with MetroWerks
Pascal.
Also add {$packrecords C} to your source to ensure that the records
are properly packed, and translate "unsigned long" using the "culong"
type from the ctypes unit rather than using uint32 ("unsigned long"
is
not the same as uint32 on all platforms, e.g. it's different on 64
bit
Mac OS X).
Thanks for the input, Jonas, and I went through all the declarations
and
found that AUNode from the AUGraph.h was wrongly specified as
"Integer", and
should be SInt32 as used in the C sample.
That did a huge difference, and the sample is now works.
That also explains why it worked on Intel and not on PowerPC: on
Intel, interpreting a 32 bit integer as a 16 bit integer is no problem
as long as the value is < 65536. On PowerPC, such a declaration
mismatch will however result in reading the upper 16 bits of the 32
bit value.
Jonas
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