DOS ain't dead - DirectDrawSurface::Blt in MPlayer

DirectDrawSurface::Blt in MPlayer (Developers)

posted by Japheth , Germany (South), 09.04.2013, 20:10

> I have a problem in emulated ddraw.dll, I'm unable to understand why but
> here some info for developers:
>
> It happens by using directx video output and requesting full screen draw
> with -fs.
> It doesn't switch resolution but instead it blits stretched.
>
> I have a video file with resolution 640x480, the screen set in .ini is
> 1024x768x16
>
> mplayer calls DirectDrawSurface::Blt()
>
> HRESULT Blt(
> LPRECT lpDestRect,
> LPDIRECTDRAWSURFACE lpDDSrcSurface,
> LPRECT lpSrcRect,
> DWORD dwFlags,
> LPDDBLTFX lpDDBltFx
> );
>
> g_lpddsPrimary->lpVtbl->Blt(g_lpddsPrimary, &rd, g_lpddsBack, NULL,
> DDBLT_WAIT, &ddbltfx);
>
> rd is 0,0,1024,768
> g_lpddsBack = @02176030
> ddbltfx is a just allocated struct but the flag is ignored
>
> with debug enabled I get this trace (values in hex)
> DirectDrawSurface::Blt, Dst=2175FBC pSF=28D0000 Rect=0 0 400 300 bpp=10
> pitch=800
>
> I've added this to debug the fill function, that is in a loop, the Blt code
> is in DDDRAW\SURFACE.ASM
> at line 663 in version 2.17 (call lpfnCopyProc) that is assigned to
> proc16to16_11 (if you set bpp=16 in ini)
>
> proc16to16_11: shr ecx, 1 ; rep movsd - esi:4031000 edi:28D0000
> ...
> proc16to16_11: shr ecx, 1 ; rep movsd - esi:40C6100 edi:29BE800
> proc16to16_11: shr ecx, 1 ; rep movsd - esi:40C6600 edi:29BF000
> proc16to16_11: shr ecx, 1 ; rep movsd - esi:40C6B00 edi:29BF800
> *** exception C0000005 EIP=2864809 EAX=800 EBX=2175FBC ECX=C0 EDX=500
> ESI=40C7000 EDI=29BFD00 FS=E7 BaseFS=125000 FS:[0]=364304 arg[1]=40C7000
>
> ---
> in hxstderr.log:
>
> dkrnl32: exception C0000005, flags=0 occured at BF:2864809
> ax=800 bx=2175FBC cx=C0 dx=500
> si=40C7000 di=29BFD00 bp=325CD8 sp=325CAC
> exception caused by access to memory address 40C7000
> ip = Module 'ddraw.dll'+3809
> [eip] = F3 A5 C3 60 68 F9 8C 86 02 FF 15 A8
> [esp] = 00000000 00127100 00325AAC 00325AAC 00325A8C 0033FA86
> dkrnl32: fatal exit!
>
> Any help is greatly appreciated
> Thanks

The reason for the crash is simple: access to address 40c7000 caused a page fault. From your debug code register ESI holds this address, which is the source of a memory block copy.

A vague guess is that the function calculates the height incorrectly.

---
MS-DOS forever!

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Complete thread:

DirectDrawSurface::Blt in MPlayer - sherpya, 07.04.2013, 08:49 (Developers)
- DirectDrawSurface::Blt in MPlayer - Japheth, 09.04.2013, 20:10
  - DirectDrawSurface::Blt in MPlayer - sherpya, 11.04.2013, 13:44
    - DirectDrawSurface::Blt in MPlayer - Japheth, 11.04.2013, 15:01
- DirectDrawSurface::Blt in MPlayer - DOS386, 10.04.2013, 11:47