Setting a byte array of 4 to the value of a long

Zap-o

I don't know if this is possible to do but, I wish to set a byte array value to a variable that is a long.

var
  byte rxdata [ 4 ] 
  long Qualifier

Pub main
  Bytemove(@rxdata,@Qualifier,4) 

Any ideas?

Heater.

How about:

LONG(@rxdata) := Qualifier

Of course that assumes that the bytes come out in the right order for your application. If not you have more work to do.

Zap-o

Okay that works but my bytes are backwards. As in rxdata [ 0 ] should be in the place of rxdata [ 3 ] and vise versa rxdata [ 3 ] should be in the place of rxdata [ 0 ]. Is there a cool byte flip operator?

*edited - solved


Thanks a million

Sapieha

Hi Zap-o.

Sorry As I say it -- It is for have nice help for other Beginners.

If You else other on write "SOLVED" ---> write even HOW it is solved even if that code are not NICE ---> it give other Beginners possibility how them need handle IT.

Zap-o wrote: »

Okay that works but my bytes are backwards. As in rxdata [ 0 ] should be in the place of rxdata [ 3 ] and vise versa rxdata [ 3 ] should be in the place of rxdata [ 0 ]. Is there a cool byte flip operator?

*edited - solved


Thanks a million

Zap-o

Yes, sorry:

I solved this problem by simply using the command that Heater mentioned. And as my 2nd post mentioned another issue was created because my bytes were backwards in the rxdata array.

original

var
  byte rxdata [ 4 ] 
  long Qualifier

Pub main
  Bytemove(@rxdata,@Qualifier,4)

What I did not mention was that Qualifier := $48454C50 'HELP

Solution

var
  byte rxdata [ 4 ] 
  long Qualifier

Pub main
 Long[@rxdata] := Qualifier

And I changed Qualifier := 504C4548 'PLEH

Sapieha

Hi Zap-o.

THANKS for understanding.

Beau Schwabe

Define your variables in the DAT section rather than the VAR section for this.

Example:

DAT

Qualifier     long
rxdata        byte 0,0,0,0

This way there isn't any conversion overhead. 'rxdata's BYTEs are aliased into 'Qualifier's LONG and vise versa.
This method also uses half the nember of LONG variables

Zap-o

Well prop code as you know is brought from EEprom into ram. However I make sure to leave some space in EEprom (address above $8000+) so that I can store data into as a make shift hard drive without having to write new firmware. The Qualifier variable is one of these values that I need to write to EEprom and store. That said DAT wont work in my situation; reason why I use the VAR.

Phil Pilgrim (PhiPi)

In general, the following is not a good way to do this:

 Long[@rxdata] := Qualifier

Why? Because it assumes that rxdata[0] is long-aligned, which may not always be the case. And, if it's not, the assignment will not work the way you want it to.

-Phil

ericball

Phil Pilgrim (PhiPi) wrote: »

 Long[@rxdata] := Qualifier

Why? Because it assumes that rxdata[0] is long-aligned, which may not always be the case. And, if it's not, the assignment will not work the way you want it to.

Good point, thus Bytemove(@rxdata,@Qualifier,4) would be the recommended method of copying a long into a series of bytes. However, if an endian swap is required then the following would work:

  rxdata[0] := byte[@Qualifier][3]
  rxdata[1] := byte[@Qualifier][2]
  rxdata[2] := byte[@Qualifier][1]
  rxdata[3] := byte[@Qualifier][0]