Returning values from objc_msgSend etc

FROM : Duncan McGregor
DATE : Fri Feb 29 20:05:28 2008

Are there any Objective-C wizards out there who could review a few
conceptual and practical issues I have returning values from
objc_msgSend and its friends?

I've just released Rococoa, a generic replacement for the Cocoa-Java
bridge, under LGPL. Some things do not work as expected on PPC. I know
I really need to understand how objc_msgSend works, but cannot find a
complete discussion anywhere.

In short, my questions are

* If both objc_msgSend_stret and objc_msgSend hack the stack to return
different sized return values, why are there 2 functions?
* Should I call objc_msgSend_stret when returning longs on PPC?
* Do I really need to call objc_msgSend_fpret for floating point on Intel?

In long, my understanding of the issue is set out here:

https://rococoa.dev.java.net/objc_msgSend.html

If anyone could spare some time reading this document and putting me
straight, you'd be helping an up-and-coming open-source project. It
might even be tax-deductible.

Thanks in anticipation

Duncan McGregor