Thank you thank you thank you thank you!

jdb

> -----Original Message-----
> From: John M McIntosh [mailto:johnmci at smalltalkconsulting.com]
> Sent: Thursday, November 14, 2002 2:04 AM
> To: squeak-dev at lists.squeakfoundation.org
> Subject: Re: On MacOSX (Re: Croquet 
> 
> 
> Air air, what day is it.
> 
> mm this would be more fun if it was generating cash.
> 
> After spending much time tinkering with the FFI code and 
> reading rather  
> old/dry manuals on powerpc assembler calling convention I 
> happened to  
> miss this gem in one of them. "Alignment Padding—Space inserted in  
> order to quadword-align the stack pointer. "
> 
> Naa, that couldn't be an issue could it? No I'm only passing 3  
> parameters into glTexParameteri, why no silly prolog code would ever  
> think about being clever and assuming they got extra bytes 
> there on the  
> stack to abuse because stacks are quadword-aligned. Nope then 
> of course
> diddling with that extra free 4 bytes in that quadword-aligned stack  
> couldn't mean I"ll override the stack chain if I wanted to stuff  
> something there at the non-existent parm 4, nope couldn't 
> conceive of  
> such a thing. Why if it did then the program would crash out in the  
> boonies and it would be ugly ugly to debug.  Certainly any 
> reasonable  
> compiler wouldn't ignore that tenant from the powerpc 
> compilers writers  
> guide, nope nope. Who in the world would need to do FFI calls 
> anyways  
> and handcraft assembler that violates the spirit of the 
> guidebook? Nope  
> not those squeaker.
> 
> If you assume someone is being clever, then debugging becomes easier.
> 
> So this gets one beyond crashing and into does it work? 
> Yes!!! I've the  
> only working carbon os-x Croquet VM on the planet. I think 
> I'll put it  
> on eBay. No? After some sleep, I'll attempt to assemble a VM 
> and a new  
> FFI tomorrow so some of you mad desperate squeakers who've 
> tossed notes  
> in my email box can waste their weekend away.
> 
> For the truly desperate what you need to do is build a new VM 
> using the  
> 3.4 image with the required
> macintosh special change sets. Then build a new mac FFI plugin and  
> change a line of code in  sqMacFFI.s
> 
> 	addi r5, r5, 24 /* linkage area */
> to
> 	addi r5, r5, 32 /* linkage area and cheat on padding */
> 
> This isn't the elegant solution, rather a raw ugly fix so I 
> can reflect  
> on the correct assembler to round up the value by 16.
> --
> ==============================================================
> ========== 
> ===
> John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
> Corporate Smalltalk Consulting Ltd.  
> http://www.smalltalkconsulting.com
> ==============================================================
> ========== 
> ===
> 
> 
> 
>