PocketMatrix

Writing to the "screen" is certainly a nasty bottle-neck on most PocketPC devices. The "problem" is that the screen buffer that GAPI passes you is generally unbuffered and uncached (so when the DMA reads it to plot to the screen there aren't "written" pixels waiting in the cache to be plotted/missed).

We've been over all this before - try searching the (entire) forum for "unbuffered" or "uncached".

Oh yeah, now I remember (reminded by Moose's post).

IIRC the 3800 series iPaq's actual LCD is "rotated" from the "old" iPaqs. So, to maintain compatability, the 3800's GAPI layer exposes an intermediary buffer and then *rotates* it into screen memory. Again, I'm sure you'll find lots about it by searching the forum.

People, Thanks for all the really useful feedback.

Ive tried the following to write my image to the screen but it doesn't work (nothing happens!). Im using the 0xac0755a0 address as suggested and removed the begindraw() and enddraw()

my code is as follows (please dont laugh)

g_gxdp.cxWidth = 240;
g_gxdp.cyHeight = 320;
g_gxdp.cBPP = 16;
g_gxdp.ffFormat = 168;
g_gxdp.cbyPitch = 2;
g_gxdp.cbxPitch = -640;

unsigned short * pusLine = (unsigned short *) 0xac0755a0;

if (pusLine == NULL) return false; // NOT OK

for (unsigned int y = 0; y < g_gxdp.cyHeight; y++) {
unsigned short * pusDest = pusLine;
for (unsigned int x = 0; x < g_gxdp.cxWidth; x++) {
PixelCol = WarpedImage[y*imagewidth+x];
*pusDest = PixelCol;
pusDest += g_gxdp.cbxPitch >> 1;
}
pusLine += g_gxdp.cbyPitch >> 1;
}

yes tried that. Stumped frankly. Is there any urls with source code examples on this topic anywhere?

What happens if you try to do a memset to video memory?

The starting address of display memory on the iPaq 3800 is 0xAC050020 (pixel location 239, 0). Try setting 153600 bytes, starting at that address, to 0xFF.

Is the resulting screen filled with white?