From: Thom Johansen <thomj_at_pvv.ntnu.no>
Date: Mon, 23 May 2005 13:30:39 +0200

Pedro Vasconcelos wrote:
>>The Coldfire processor we're using has 96kb of fast internal single
>>cycle access RAM. The slow accesses we get from ordinary RAM is a pretty
>>big bottleneck, so using this is beneficial.
>>You can put a variable/array/whatever in IRAM by postfixing the
>>definition with IDATA_ATTR, like this:
>>int myarray[512] IDATA_ATTR;
>>vorbis2wav doesn't support this right now, but I'll commit a fix for
>>this in five minutes.
>
> That's very interesting. Is it a cache or a separate memory range?
It's a separate memory range. The Coldfire has no ordinary data cache,
though it has a code cache which is also very important to utilise
properly.

> I ask
> this because most of the mdct functions take pointers: should IDATA_ATTR
> be used at the allocation point or the usage point?
>
> Anyway we have chose carefully what to use for because Tremor is using
> ~300kb at the moment (maybe there is a leak as well...)
The only place you need to worry about it, is when you define the
variable. Using IRAM together with malloc()-like functions is pretty
much out of the question, since IRAM usage needs to be tightly
controlled.

Thom
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Received on 2005-05-23