[tremor] Memory optimizations

[John Ripley]

> From: PALFFY Daniel [mailto:dpalffy-lists at rainstorm.org]
> Sent: 29 March 2004 19:51
> To: tremor at xiph.org
> Subject: [tremor] Memory optimizations
> 
> I want to make tremor work on the Apple iPod on the uClinux 
> platform (for more info, see http://ipodlinux.sf.net/).
> 
> The ipod has two arm7tdmi cores running at up to 90MHz, so 
> this should be
> no problem. My problem is with memory bandwidth - the 32MB 
> main memory is
> connected to the CPUs on a very slow bus. But we have 96kB fast SRAM.
> Unoptimized ivorbisfile_example runs at about 50-80% speed 
> depending on
> bitrate.
> 
> Any ideas what parts of code/data should I put to fast memory?

It's mostly the same hardware in a Rio Karma and Tremor (not lowmem) fits
real time on a single core without any tweaking at all, I believe - just
running out of cached SDRAM. The biggest improvement will be to move the
working vector into SRAM and doing the iMDCT there. Basically move anything
which will thrash the cache into SRAM. I wouldn't bother moving code.

- John Ripley.
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