[Vm-dev] VM patches for oop comparison and usqInt declarations

[John M McIntosh]

Ah well something else wrong I guess.

let's see  -0x0A is 0xFFFFFFFF6

mmm add say + 4 is 0xFFFFFFFA or (-0x06)

need more coffee.


On May 7, 2007, at 6:35 PM, Bert Freudenberg wrote:

>
> On May 7, 2007, at 17:25 , John M McIntosh wrote:
>
>> Ok, I was working with Craig a bit on this and I noticed for example.
>>
>> usqInt endOfMemory;
>>
>>    sqInt fwdBlock2;
>>
>> 		/* begin restoreHeadersAfterForwardBecome: */
>> 		fwdBlock2 = ((foo->endOfMemory + BaseHeaderSize) + 7) &  
>> (WordMask - 7);
>> 		flag("Dan");
>> 		fwdBlock2 += BytesPerWord * 4;
>>
>>
>> Really shouldn't one consider that if a unsigned value gets  
>> assigned to a signed integer one should really consider that a  
>> possible problem?
>>
>> Needless to say I believe the code above won't work as intended.
>
>
> Shooting from the hip and all, but I'd say thanks to two's  
> complement this actually should work. Far from pretty or desirable,  
> but it should generate the same code (unless the C compiler inserts  
> specific checks which it should not and AFAIK it does not).
>
> - Bert -
>
>

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John M. McIntosh <johnmci at smalltalkconsulting.com>
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
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