[En-Nut-Discussion] network throughput gain (nicrtl output)

[Damian Slee]

Hi,
anyone know of a good ARM9/ARM7 GCC toolchain? 
preferably compiled to use under windows, Like WinAVR.  If there was one around, more of us probably would use an ARM.

There are some nice ARM processors out there with lots of flash and RAM on chip.

-----Original Message-----
From: Ralph Mason [mailto:ralph.mason at telogis.com]
Sent: Monday, 1 December 2003 8:02 AM
To: enut at ixo.de; Ethernut User Chat (English)
Subject: RE: [En-Nut-Discussion] network throughput gain (nicrtl output)



If your using a CPLD why not just do a DMA mode?

Set a Read address and a write address, and a number of bytes and set it
going, with an output done line.

You could clock it from the same crystal as the AVR and do a byte per clock.
Then in the AVR code you set it up and wait for the done line.

But if you do all this why not just use a faster chip some ARM variant
perhaps, and get rid of the CPLD etc altogether.  They are as cheap as an
mega128 these days anyway.

Ralph


> -----Original Message-----
> From: en-nut-discussion-bounces at egnite.de
> [mailto:en-nut-discussion-bounces at egnite.de]On Behalf Of Waschk,Kolja
> Sent: Monday, 1 December 2003 10:55
> To: Ethernut User Chat (English)
> Subject: Re: [En-Nut-Discussion] network throughput gain (nicrtl output)
>
>
> > If I'm not wrong, this is even 1 cycle faster.
>
> > .L94:
> >  ld r24,Z+
> >  sts -16376,r24
> >  subi r22,lo8(-(-1))
> >  sbci r23,hi8(-(-1))
> >  brne .L94
>
> 4+4+1+1+2 = 12 cycles per byte, whereas
>
> >> .L94:
> >>   ld r24,X+
> >>   std Y+16,r24
> >>   subi r18,1
> >>   brcc .L94
> >>  subi r19,1
> >>  brcc .L94
>
> 4+4+1+2 = 11 cycles most of the time,
> 4+4+1+1+1+2 = 13 cycles only at 8 bit boundary
>
> For 536 bytes that's about 9% gain
>
> To push throughput even more, I'm currently playing with the idea of
> implementing an operating mode where m128 issues a read from RAM
> and some logic
> (CPLD) translates this into a write access to the MAC at the same
> time (RAM
> outputs data, MAC reads it).  Thus no explicit write instruction would be
> needed, and the inner loop would shrink to 7 cycles. Anyone tried
> something
> similar before?
>
> Kolja
>
> --
> mr. kolja waschk - haubach-39 - 22765 hh - ger
> phone +49 40 889130-34 - fax -35 - e-mail s.a.
>
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