VAR Aliases...

DToolan

If I create a word var (or any other kind of var)... can I somehow create a byte array that resides on top of that var so I can access each byte without having to mask and shift?

Example:

Word MyWordVar
Byte MyByteArray[2] @MyWordVar '<- MyByteArray actually lives on top of the memory locations of MyWordVar

MyWordVar := $AA55

'MyByteArray[0] should equal $55 and MyByteArray[1] should equal $AA without having to mask and shift MyWordVar into seperate bytes

Duane Degn

You can access the bytes this way.

VAR
  word MyWordVar
  byte MyByteArray[2] 
PUB Main
 
  MyByteArray[0] := byte[@MyWordVar] 
  MyByteArray[1] := byte[@MyWordVar + 1]
 

I doubt it's what you're looking for but you don't have to shift the bits.

In this example MyByteArray[1] will hold the least significant byte (I'm pretty sure).

Also (as I'm sure you know) MyByteArray wont change automatically when you change MyWordVar. Which, if I understand you correctly, is your main objective (which my example fails to do).

Maybe some else has a better idea?

Duane

kuroneko

DToolan wrote: »

If I create a word var (or any other kind of var)... can I somehow create a byte array that resides on top of that var so I can access each byte without having to mask and shift?

That won't work for various reasons (reordering of long/word/byte etc). What you can do is access smaller units of a long like value.word[0] or value.byte[2] or of a word like value.byte[1].

Beau Schwabe

If you use the DAT section, here is one way to alias the BYTE,WORD, and LONG variables without any program overhead...

http://forums.parallax.com/showthread.php?112970-Word-Sized-constant-in-Byte-array&p=808493&viewfull=1#post808493

Main Reference Thread:
http://forums.parallax.com/showthread.php?112970-Word-Sized-constant-in-Byte-array


Pertinent information:

DAT
L0            long
W0            word
W0_lowbyte    byte      0
W0_highbyte   byte      0
W1            word
W1_lowbyte    byte      0
W1_highbyte   byte      0

DToolan

Thank you all very much for your information. It was very helpful.