Patch to increase lcd speed on the ipod video.

Decreases runtime of lcd_update_rect by an average of 0.1 ticks per
call, or 1 millisecond; and up to three milliseconds max. This
increases the maximum frame rate by about one to one-and-one-half
frames per second.

Using the test_fps plugin, the results for the unmodified code, on my
ipod, are:
1/1 21.5 fps, 1/4 44.5 fps, with CPU at 30MHz
1/1 37.0 fps, 1/4 57.0 fps, with CPU at 75MHz

With this patch, my results are:
1/1 22.5 fps, 1/4 46.0 fps, with CPU at 30MHz
1/1 38.5 fps, 1/4 58.0 fps, with CPU at 75MHz

The patch uses Duff's Device to unroll a loop.

Patch can be found here: http://www.rockbox.org/tracker/task/5432
Received on Fri May 26 08:00:17 2006