Reading Data from a string and comparing.

Paul K.

Im having a hard time starting this on my own.· I am using the wireless playstation remote object and I have that working and
displaying that data thru my rca connection.

It's displaying the data in hex so I get something like this $FFFF5A73 this changes as I hit a button on the remote.
I have mapped out all the changes possible.

I am lost on how to read a change.·

EX: I hit the triangle button and I·get this in return $EFFF5A73 but am lost how to read the first bit in the sequence.
I know I can compare the whole string but thats alot of wasted time if each bit has 16 different options im looking at a table of like
a couple thousand different options.· If not more.· Is there a way to read each bit.

Thanks
Paul

Beau Schwabe

Paul K.,

If the lower bits are insignificant in your comparison you can do something like this...

   If hex_data>>24 & $FF == $EF
      {triangle button pressed}

third_num
or even...

{triangle button pressed}{triangle button pressed}
   If hex_data>>28 & $F == $E
      {triangle button pressed}

If you want to look at a different position, say the 3rd one from the right where the 'A' is ... $FFFF5A73

you could do something like this...

  eigth_num := hex_data>>28 & $F
  third_num := hex_data>>8 & $F

  if third_num == $A 
     {do something here}   
   
  if eigth_num == $E 
     {triangle button pressed}

since Each HEX value represents 4 bits, the number to shift is the position from the right minus 1 times 4.

so for the 8th position... (8-1)*4 = 28
...the 3rd position... (3-1)*4 = 8


If the number that you want to look at is a BYTE (8-bits) ... same thing, but instead of multiplying by 4, multiply by 8.

in the first example... 'If hex_data>>24 & $FF == $EF'

...this was the 4th BYTE from the right... so (4-1)*8 = 24

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 10/19/2009 5:12:02 AM GMT

Paul K.

Pretty straight foward. Alot simpler than I thought.

Thanks
Paul