Q;Accumulators?

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
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shawn
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Q;Accumulators?

Postby shawn » Thu Feb 11, 2010 12:32 am

Can someone point me in the right direction for more insight on accumulators in Xmos.
How many are there, how general are they? I'am just interested for semantical reasons?

Thank you,
shawn
richard
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Postby richard » Thu Feb 11, 2010 11:05 am

Are you referring to the multiple accumulate instructions? There are no dedicated accumulator registers, the maccs / maccu instructions can use any pair of the 12 general purpose registers r0 - r11 as the accumulator. These instructions multiply two words and add the double word result into a double word accumulator.
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shawn
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Postby shawn » Thu Feb 11, 2010 12:02 pm

Richard,
That answers my question . I can get the instructions, no problem.
I just wanted reference to what and how. You got that quick.
Thank You,
Shawn
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leon_heller
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Postby leon_heller » Thu Feb 11, 2010 12:10 pm

There are actually 16 registers.

Leon
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shawn
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Postby shawn » Thu Feb 11, 2010 10:38 pm

How do you look at the reg stack do you break it up.
8 for Fast links 8 for all else. so an interupt can occur
every .00000001sec. so, 4 events to one interup max, or is
it possible with 4 mult channels to 1/4 sync interups to
optane .0000000025 sec. at any given. Its just a question
out of curiousity, And most likely not logical.
Thought's appreciatted...
Shawn
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paul
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Postby paul » Fri Feb 12, 2010 1:37 pm

leon_heller wrote:There are actually 16 registers.

Leon
Well... sort of - not all of them are General purpose. Some of them can be written to but not have other operations done on them (e.g Link Register - can have a value loaded into it but you can't do math ops on it).
Paul

On two occasions I have been asked, 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.
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shawn
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Postby shawn » Sun Feb 14, 2010 9:26 am

Thanks for helping, the number of acumultators & registers strikes my interest. some of the old
architectures, had several accumultors & registers unlike modern register rich designs. Today
we have an exponetial quanity of silicon at our disposal. I'd like to exploit best tricks, to XMOS.
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