On Thu, 13 Feb 2003, Russell McMahon wrote:

> Scott D mentioned looking at ARM a while ago AFAIR.
> Maybe he has some comment to make on hood entry paths?

Sure!

Any takers on guessing what this does:

; R0 7-0 = data
; R1 15-0 = crc
;

    eor    R0,R0,R1 LSR 8    ; R0 = t = (crc>> 8) ^ data
    eor    R0,R0,R0 LSR 4    ; R0 = t ^ (t>>4)
    eor    R1,R0,R1 LSL 8    ; R1 = (crc << 8) ^ t
    eor    R1,R1,R0 LSL 5    ; R1 = (crc << 8) ^ t ^ (t<<5)
    eor    R1,R1,R0 LSL 12   ; R1 = (crc << 8) ^ t ^ (t<<12)

Okay, yeah, it's a CRC algorithm, but which one?

In my opinion, the ARM processor is a very logical next step for PIC's.
The ARM cores address the same type of markets addressed by PIC's and
other microcontrollers. The difference of course is that the ARM is a much
more powerful processor and can address a broader range of markets.

For example, I've been using the Atmel's AT91R40008 along with a Synaptics
capacitive sensing ASIC to build an extremely low power, stand-alone
Chinese Character Recognition module:

http://www.synaptics.com/press/pr_detail.cfm?prid=66

I'm quite certain that no PIC (or any other 8-bit microcontroller) can
come anywhere close to solving this problem. However, I'm also quite
certain that the experienced I gained working with 8-bit microcontrollers
for many years has helped in working on the ARM.

Scott

PS. Incidently, I'm not subscribed to [ot]: threads, but this one for some
reason is getting through.

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