Porting troubles

Wim Boot wimb at bart.nl
Fri Jul 17 12:23:16 UTC 1998

John Maloney wrote:

>>As I read it the memory has been malloced high up and all those ints that
>>represent addresses have become negative, breaking the pointer arithmetic.
>>So...shouldn´t all variables that hold addresses (OOPs) be declared as
>>unsigned instead of int (or am I barking up the wrong tree) ?
>Yes, or (void *) perhaps. But I'd hate to have to put all
>those type declarations into the Smalltalk code that is used
>to generate the C code for the VM...

This highlights a strange issue I found when looking at the interpreter
simulator: the simulator code treats everything in memory as unsigned
whereas the generated C-code treats it, with a few explicit exceptions,
as signed. Perhaps the best solution is to make the default declaration
in the C-code unsigned and fix the places where signed is essential.
Could still be a lot of work though...

Using void* carries a risk. Nothing in the C standard prevents a compiler
from generating signed comparisons between pointers. And yes, I have
learned this the hard way; it's not entirely hypothetical.

Wim Boot

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