rotate bytes in array

[Art]

Hi Guys,
I want to rotate all bytes (bytewise) in an array of 30 bytes so that the oldest value in the array is discarded
from one end, and a new value is placed in the other end, and the new value should be the last to be discarded.

A seemingly simple problem driving me nuts!
Something like this would just copy the new value to all bytes:

FOR gcnt = 0 TO 29 '
vmean[gcnt+1] = vmean[gcnt] '
NEXT gcnt '

Any help appreciated.
Cheers, Brek.

[Art]

Something like this:

ii = 29 '
FOR gcnt = 1 to 29 '
vmean[ii] = vmean[ii - 1] '
ii = ii - 1 '
NEXT gcnt '
'
vmean[0] = newvalue '


(I think is right)

[languer]

Seems right. Out of curiosity, what are you using this for?

[Art]

Adding a new voltage reading every second to calculate a new mean voltage over thirty seconds for a low voltage cutout.

[Demon]

Why not:

FOR ii = 29 TO 1 STEP -1
vmean[ii] = vmean[ii - 1]
NEXT ii

vmean[0] = newvalue

I don't have the manual nearby, but I'm pretty sure we can go backwards.

Robert

[MikeWinston]

instead of a for/next shift, how about a in-place overwrite. (instead of shifting the data, shift the index variable.)

index = 0

Loop:
adResult = {...new voltage value}

arraySum = arraySum - arr[index]
arr[index] = adResult
arraySum = arraySum + adResult

if index = 29 then
index = 0
else
index = index + 1
endif

goto Loop


Mike -

[Art]

Mike, is the compile size smaller?
I can't really check in my project because it appears code is being fragmented over several pages
after I crossed the first boundary.

Robert, Didn't know you could use a STEP -1 directive,
but if it works, it's shorter, and saves a useless byte.

It appears to be working nicely, but I will shorten it if possible.
It's for my car computer I've posted about here before.
With the vehicle running, the voltage reading is live.
With the engine stopped, but accessories relay on,
the stereo amplifiers tend to cause the voltage to jump around (understandably).
The thirty second average is then displayed and acted on to turn accessories off if the average is too low.

[MikeWinston]

Art,
don't know if it's smaller. i was going for speed rather than code size.

Mike -

[Demon]

...Robert, Didn't know you could use a STEP -1 directive,
but if it works, it's shorter, and saves a useless byte...

Yup, got off my lazy butt and got the manual, it's in there.

So far our score in PBP knowledge:
Robert 1 .... Art 56,743