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Subject: Re: things to optimize (was Re: Testers wanted: up to 50% greater battery life)
From: Daniel Stenberg (
Date: 2003-07-30

On Wed, 30 Jul 2003, TP Diffenbach wrote:

> Oh dear. Is the update smart enough to not update non-scrolling,
> non-changing lines?

No. lcd_update() writes the full frame buffer to the LCD.

For each 8 y-pixels there are 3 commands written, then there's one byte
written for each pixel column.

8*3 + 8*112 = 920 invokes of lcd_write().

That's also why we added lcd_update_rect() which only updates a given

Certainly we can make a function that doesn't update bytes that haven't
changed, but the major boost tend to be to just to not call lcd_update() more
than necessary.

> The settings code may or may not take longer; the salient point is the
> settings code really isn't needed except for two of the <however many
> settings there are now>. The other salient point is that we swouldn't need
> to do this at all if we could do a clean shutdown that saved settings.

 Remember that we only write to the RTC that often. We write to disk when
there's a actual disk activity triggered by other means.

 Daniel Stenberg -- --

Page was last modified "Jan 10 2012" The Rockbox Crew