On 8 May 2010 20:01, Andreas Raab <andreas.raab at gmx.de> wrote:
> On 5/8/2010 9:54 AM, Ang BeePeng wrote:
>>
>> sqInt primitiveReturnString(void){
>>        sqInt* tempPtr = 0x111EB8D4;
>>        sqInt temp;
>>
>>        temp = popStack();
>>        if(isIntegerObject(temp))
>>                dllMemory[dllResult] = temp;
>>        else{
>>                *tempPtr = temp;
>>                dllMemory[dllResult] = temp; //I'm not sure what to do with
>> this yet
>>                addGCRoot(tempPtr);
>
>                ^^^^^^^^^^^^^^^^^^^
>
> This is wrong. It needs to be
>
>                addGCRoot(&tempPtr);
>                         ^^^
>
no, it is right, except that i don't understand the Ang's choice of
taking an arbitrary constant to serve as a memory pointer.
In fact, its equivalent to:
 addGCRoot( (sqInt*)0x111EB8D4);

because a pointer value initialized with this constant, and storing a
oop at that memory location,
obviously, doesn't affects the pointer itself.

> The call takes a variable location (pointer to a pointer). The contents of
> the variable is then updated.
>
> Cheers,
>  - Andreas
>
>
>>
>>        }
>>        pop(1);
>>        interpReturn = 1;
>> }
>>
>> I start up SqueakVM, and execute primitiveReturnString() with a float on
>> top
>> of the stack. After this primitive, SqueakVM is allow to run on its own.
>> And
>> then I got an access violation, with call stack look like this.
>>
>>        Squeak4.dll!markAndTrace(int oop=0)  Line 11883 + 0x3 bytes     C
>>        Squeak4.dll!markPhase()  Line 12221 + 0x9 bytes C
>>        Squeak4.dll!incrementalGC()  Line 5578  C
>>        Squeak4.dll!instantiateContextsizeInBytes(int
>> classPointer=275821428, int
>> sizeInBytes=92)  Line 6218      C
>>        Squeak4.dll!allocateOrRecycleContext(int needsLarge=0)  Line 2553 +
>> 0x10
>> bytes   C
>>        Squeak4.dll!interpret(int * sharedMemory=0x0015fabc, int rcvr=0,
>> char *
>> selector=0x0015fc54, int arg=1, int result=2)  Line 8485 + 0xc bytes    C
>>        Squeak4.dll!SqueakInterp2(int * sharedMemory=0x0015fabc, int
>> rcvr=0, char
>> * selector=0x0015fc54, int arg=1, int result=2)  Line 10 + 0x19 bytes   C
>>        MainProgram.exe!main()  Line 49 + 0x19 bytes    C
>>        MainProgram.exe!__tmainCRTStartup()  Line 586 + 0x19 bytes      C
>>        MainProgram.exe!mainCRTStartup()  Line 403      C
>>        kernel32.dll!76b91194()
>>        [Frames below may be incorrect and/or missing, no symbols loaded
>> for
>> kernel32.dll]
>>        ntdll.dll!7767b435()
>>        ntdll.dll!7767b408()
>>
>> or sometimes, it is like this:
>>
>>        Squeak4.dll!incCompMakeFwd()  Line 5368 + 0xc bytes     C
>>        Squeak4.dll!incCompBody()  Line 5260 + 0x5 bytes        C
>>        Squeak4.dll!incrementalGC()  Line 5588  C
>>        Squeak4.dll!sufficientSpaceAfterGC(unsigned int minFree=202504)
>>  Line
>> 23654   C
>>        Squeak4.dll!primitiveNew()  Line 17781 + 0x9 bytes      C
>>>
>>>        Squeak4.dll!dispatchFunctionPointer(void *
>>> aFunctionPointer=0x100403c5)
>>
>> Line 4097       C
>>        Squeak4.dll!interpret(int * sharedMemory=0x001dfd48, int rcvr=0,
>> char *
>> selector=0x001dfee0, int arg=1, int result=2)  Line 8458 + 0xb bytes    C
>>        Squeak4.dll!SqueakInterp2(int * sharedMemory=0x001dfd48, int
>> rcvr=0, char
>> * selector=0x001dfee0, int arg=1, int result=2)  Line 10 + 0x19 bytes   C
>>        MainProgram.exe!main()  Line 49 + 0x19 bytes    C
>>        MainProgram.exe!__tmainCRTStartup()  Line 586 + 0x19 bytes      C
>>        MainProgram.exe!mainCRTStartup()  Line 403      C
>>        kernel32.dll!76b91194()
>>        [Frames below may be incorrect and/or missing, no symbols loaded
>> for
>> kernel32.dll]
>>        ntdll.dll!7767b435()
>>        ntdll.dll!7767b408()
>>
>>
>> sometimes, it is at remap() as I mention earlier.
>>
>> At extraRoots[1] I can see 0x111EB8D4, which is still tempPtr. But at
>> 0x111EB8D4, I see some non address value which is for example 0x00000002.
>>
>> Thanks.
>>
>> Ang Beepeng
>
>
>



-- 
Best regards,
Igor Stasenko AKA sig.