How will longfill overwrite in this program?

jacksons

If I have a program such as this:

VAR
  long buffer[100]
PUB main
  long sensorval := 'get sensor reading
  longmove(@buffer+1, @buffer, 99)
  buffer[0] = sensorval

I was wondering if longfill would actually shift the array or overwrite it in an unexpected way.

T Chap

Welcome Jacksons. Why not just shift with long move then put the new sensor value at element 99 of the array? I haven't testing longmove in the direction you are trying to go.

Dave Hein

longmove checks the starting addresses of the two buffers, and will begin copying from either the beginning or the end depending on the order of the addresses. This makes it possible to shift the contents of an array. At least that's the way I understand it. You should test it to make sure.

EDIT: You did mean to say longmove, and not longfill in your last sentence, right?

Electrodude

It will shift the array as you would expect and not overwrite it. The spin interpreter automatically figures out if it should copy it from bottom to top or top to bottom so bad overwrite things don't happen.

electrodude

EDIT: This is what happens when I load twenty tabs and end up taking so long to read them all that I get ninja'd by 7 minutes. Maybe I should reload before posting next time...

T Chap

Thanks for the correction Electro.

Duane Degn

I've tested this many times myself. The various "xxxxMove" statements work great when shifting an array. As Electrodude said, the Spin interpreter makes sure it preserves the data.

I used to frequently make use of the move statements until Phil exhorted someone doing the same to learn to use a circular buffer. Since taking Phil's advice (to someone else) I find I don't need to shift buffers with "move" statements much.

kuroneko

You also want either longmove(@buffer/COLOR]1[COLOR="#FF0000", @buffer, 99) or longmove(@buffer+4, @buffer, 99).