Question : Writing bits to screen in Direct Draw

I have an array of bytes which encode pixel values (they are palettized) and I want to draw this to the screen as fast as possible. Basically my function looks like this:

void __fastcall
draw(__int8* line, int lineCount)
{
// Line points to an array of bytes where each byte encodes 2 pixel values, e.g.
// line -> [0x0F, 0x52, ...] Is pixels 0,F,5,2
//           A single line of the array is guarnateed to be exactly 128 bytes (corresponding to 256 pixels)
// lineCount is the number of lines that the buffer points to
}

void __fastcall
endDraw()
{
// Once I accumulate 240 lines, I need the data to actually go onto the screen
// I'm using DirectX (DirectDraw) and am hoping that all that I have to do here is call flip on my primary surface.
}

If there is a better format for the data to be in, that can possibly be managed, but since the surface can only show 16 colors I was thinking that this would be a good format.

The target platform is going to be a PocketPC-type device which is the reason that I'm not using D3D.

Thanks in advance.

Answer : Writing bits to screen in Direct Draw

You're right, pixel plotting would be slow. I dont know the specifics because you haven't told me the processor but I can imagine that the hit would be fairly severe. You should be able to use a memcopy to copy a line from system to video memory. Once you lock the surface and get a pointer to the first pixel. If you have a contiguous surface then you could memcopy the whole block over in one call which would probably be your fastest option - though referring to point 1 in my previous email it might be faster to work with the video memory directly depending on the specific bus speeds of the target device.