Move seperate bytes into a word

[tazntex]

How can I combine these bytes into a word size variable? I am using only four bits of the bytes "0-3" and would like to place them into a word in such a way that "Z" holds A= 0-3, B= 4-7, C=8-11,and D=12-15.
Example:

A=%00000001
B=%00000010
C=%00000011
D=%00000100

Z=0100001100100001

I was thinking of using Aliases in the manual but not sure if that was a way to do it.

I really didn't want to do this:
z.0=a.0
z.1=a.1
etc.
Thanks

[Ioannis]

Something like this?

z=a+b<<4+c<<8+d<<12

Ioannis

[tazntex]

Thank you very much, never thought of that. I will try it out.

[mister_e]

"Z" holds
A= 0-3,
B= 4-7,
C=8-11,and
D=12-15.

First thing is to isolate each 4LSB of each variable. Easy way, using boolean AND (&)

A = A & $0F
B = B & $0F
C = C & $0F
D = D & $0F

Now, you need to shift some bits of your Bytes variables. This is done using left shift (<<). Check your manual about that. Knowing that, we could modify the above like

A = A & $0F
B = B << 4  
C = C & $0F
D = D << 4

Now you need to combine A & B, and C & D, then the whole thing together. Boolean OR do the trick

A = (A & $0F) | (B <<4)  ' a hold A & B
C = (C & $0F) | (D <<4)  ' C hold C & D

Then you need to send A and C where they're suppose to go in Z

Z.LowByte = A
Z.HighByte = C

A is now LSB of Z(0-7), C is now MSB of Z(8-15).

This could be shorten like

Z.LowByte = (A & $0F) | (B <<4)  
Z.HighByte = (C & $0F) | (D <<4)

If you're REALLY SURE you NEVER EVER mess with bits <7:4> of your variables, then yes, this could reduce to

Z.HighByte = (D<<4) | C
Z.LowByte = (B<<4) | A

OR

Z = (D<<12) | (C<<8) | (B<<4) | A

I see other ways, but this should be more than enough to start

[mister_e]

One step further..

Z VAR WORD
A VAR Z.LOWBYTE
B VAR BYTE
C VAR Z.HIGHBYTE
D VAR BYTE

'
'    Some other code where you set A, B, C & D BYTE variables
'

Z.HIGHBYTE = Z.HIGHBYTE | (D<<4)
Z.LOWBYTE = Z.LOWBYTE | (B<<4)
' Now you have everything in Z... easy huh?

or.. yet another

Z = Z | (B<<4) | (D<<12)

Enjoy

[tazntex]

I've tried Ioannis suggestion and it seems to work fine, I'll will try the others to. I do not plan to ever use bits 7-4 so I will give these a try. I am just playing around trying to see what does and does not work. I learned something new and appreciate all the help.

Again, Many Thanks

[Ioannis]

Steve's solutions cover the case that high nibble could hold some bits at 1 and masks to zero. Mine is based on the assumption that high nibbles will always be 0.

It would also be interesting to know which way is less memory hungry.

Ioannis