Re: [AD] crash 16bit fullscreen mode

[aj <aj@xxxxxxxxxx>]

i have a theory...

i think i have found a race condition where the graphics driver may be 
drawing to a surface it no longer has locked, due to alt-tabing away from 
the app.   is that possible ?
could it be that during the alt-tab away, the screen bitmap is lost and 
attempting to draw on it causes a crash ?
this problem has only been reported to me by some users that claim its a 
recent bug, so maybe its a change that occured between 4.1.15 and 4.1.16 ?



> winXPsp1
> msvc7.1 (.net)
> allegro 4.1.16
>
> my allegro app crashes in 16bit mode, running on a 16bit desktop.
> when i alt-tab away from the fullscreen driver it crashes.
>
> it does not crash in the debug mode.
> only the release version.
>
> i also tried 32bit desktop and it does NOT crash.
>
>
> here is the only info i could find.. the crash location is marked with an 
> arrow.
>
>
> 005088ED  dec         ecx
> 005088EE  jne         005088E0
> 005088F0  movs        word ptr [edi],word ptr [esi]
> 005088F2  mov         ds,bx
> 005088F4  inc         dword ptr [ebp+14h]
> 005088F7  inc         dword ptr [ebp+1Ch]
> 005088FA  dec         dword ptr [ebp+24h]
> 005088FD  jg          005088BC
> 005088FF  emms
> 00508901  jmp         00508A74
> 00508906  mov         esi,esi
> 00508908  mov         edx,dword ptr [ebp+0Ch]
> 0050890B  mov         eax,dword ptr [ebp+1Ch]
> 0050890E  mov         edi,dword ptr [ebp+18h]
> 00508911  call        dword ptr [edx+20h]
> 00508914  lea         edi,[eax+edi*2]
> 00508917  mov         edx,dword ptr [ebp+8]
> 0050891A  mov         eax,dword ptr [ebp+14h]
> 0050891D  mov         esi,dword ptr [ebp+10h]
> 00508920  call        dword ptr [edx+24h]
> 00508923  lea         esi,[eax+esi*2]
> 00508926  mov         ecx,dword ptr [ebp+20h]
> 00508929  mov         ds,word ptr [edx+3Ch]
> 0050892C  movq        mm0,mmword ptr [esi]
> 0050892F  add         esi,8
> -----> 00508932  movq        mmword ptr es:[edi],mm0
> 00508936  add         edi,8
> 00508939  dec         ecx
> 0050893A  jne         0050892C
> 0050893C  mov         ds,bx
> 0050893E  inc         dword ptr [ebp+14h]
> 00508941  inc         dword ptr [ebp+1Ch]
> 00508944  dec         dword ptr [ebp+24h]
> 00508947  jg          00508908
> 00508949  emms
> 0050894B  jmp         00508A74
> 00508950  mov         edx,dword ptr [ebp+0Ch]
> 00508953  mov         eax,dword ptr [ebp+1Ch]
> 00508956  mov         edi,dword ptr [ebp+18h]
> 00508959  call        dword ptr [edx+20h]
> 0050895C  lea         edi,[eax+edi*2]
> 0050895F  mov         edx,dword ptr [ebp+8]
> 00508962  mov         eax,dword ptr [ebp+14h]
>
>
>
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