mkt059@ipl.jpl.nasa.gov (Mike Tschudi (Cartographic Applic.)) (11/26/90)
Has anyone had experience with SwapMMUMode or 32-bit QuickDraw's GetPixBaseAddr? I'd like to alter the values of pixels in an offscreen GWorld, but GetPixBaseAddr says that it returns a 32-bit pointer that is the only way to get to the offscreen GWorld's PixMap, and SwapMMUMode crashes my Mac (IIcx using Think C 4). Michael Tschudi Cartographic Applications Group Jet Propulsion Lab, Pasadena, CA
russotto@eng.umd.edu (Matthew T. Russotto) (11/28/90)
In article <77758@ipl.jpl.nasa.gov> mkt059@ipl.jpl.nasa.gov (Mike Tschudi (Cartographic Applic.)) writes: >Has anyone had experience with SwapMMUMode or 32-bit QuickDraw's >GetPixBaseAddr? > >I'd like to alter the values of pixels in an offscreen GWorld, but >GetPixBaseAddr says that it returns a 32-bit pointer that is the >only way to get to the offscreen GWorld's PixMap, and SwapMMUMode >crashes my Mac (IIcx using Think C 4). There is a tech note on this-- what happens is the PC looks like this: XXYYYYYY, so when you swapMMUMode, those XXs cause the machine to go off into lala land and crash. You need a bit of inline assembly to fix the PC so it looks like 00YYYYYY before you call SwapMMUMode. -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu .sig under construction, like the rest of this campus.
ph@cci632.UUCP (Pete Hoch) (11/29/90)
In article <77758@ipl.jpl.nasa.gov>, mkt059@ipl.jpl.nasa.gov (Mike Tschudi (Cartographic Applic.)) writes: > Has anyone had experience with SwapMMUMode or 32-bit QuickDraw's > GetPixBaseAddr? > I'd like to alter the values of pixels in an offscreen GWorld, but > GetPixBaseAddr says that it returns a 32-bit pointer that is the > only way to get to the offscreen GWorld's PixMap, and SwapMMUMode > crashes my Mac (IIcx using Think C 4). I think you will find that the documentation for GetPixBaseAddr said that you may get a 32 bit address back. There is another call to find out if it really is a 32 bit address. Now ask yourself, "Where would a 32 bit address come from, since my Mac runs in 24 bit mode?" The answer my friend is ridding on the NuBus. If you want to support the 8/24 GC graphics card from Apple then you may get a 32 bit address. If you don't care about this card, then do not worry. If you want to do the right thing and supprot it, then I suggest you get a real development system where you can call SwapMMUMode. ;=] Pete Hoch