PocketMatrix

We've discussed this elsewhere before, but just in case it helps, the StrongARM based hardware (usually) works like this:

There is no specific buffer to hold video memory (i.e. no VRAM). The buffer that's displayed is sitting somewhere in the SDRAM.

Usually the StrongARM's internal LCD controller (and corresponding DMA) is used to transfer the contents of the "screen" from the buffer to the LCD in chunks of 16 bytes (IIRC).

The LCD's DMA is the highest priority device in the system - i.e. if the LCD is screaming for data then even the CPU is blocked out until it's serviced.

Bear in mind that normally the buffer(s) that are used for the LCD are unbuffered and uncached. They're slow to access and use. A blit to screen is really just a memcpy() to the uncached buffer that the DMA is using from whatever (usually cached) buffer that you plotted into.

The update of the LCD is limited to the refresh rate of the LCD in the device (IIRC for Ipaq's it's 70Hz).
There's no easy way of getting a vsync hooked up, so 70Hz isn't a hard limit - it's just pointless going above it.

HTH,

Ref.

You know, I decided long ago to hard-code all my work to 30FPS. That way I can pretty much guarantee it will maintain a steady frame rate on any device (I use my stock E-125 as a baseline... if it can churn out 30FPS in whatever I'm doing consistently, I know I'm good on any modern device).

So, let me pull a Bill Gates here...

"30FPS should be enough for anybody!"

And if your still not laughing, try coding on a C64 where your trying to update a color table in between HORIZONTAL SCAN RETURNS (approximately 1/3 of 1/30 of a screen refresh, give or take, I forget... It WAS 15 years ago!)

Thanks Refractor for clearing this up. I figured it was something like that, but I wasn't sure.

And I have to agree with fzammetti too. 30 FPS should be enough for everyone.

Personal remark: Coding for C64. Respect! I only played games on my C64 (and I still have a working C64 in a box back at my parents house. One of the joysticks has stopped working but I hope I can fix it during the summer. Who needs Playstation II when you got Krackout, 1942 and the Last Ninja on C64?)