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Assigning byte variable from a long/word value? — Parallax Forums

Assigning byte variable from a long/word value?

I have some network stuff I'm doing as byte arrays, and I need to fill in some of them with values I'm getting from words. Do I need to bother doing the following:
a[0] := (b>>8)&$FF
a[1] := b&$FF
Or does it only copy the bottom 8 bits regardless, in which case the &$FF is wasted cycles?

Comments

  • JonnyMacJonnyMac Posts: 8,054

    if a is an array of bytes, then any simple assignments to it will be truncated to 8 bits.

    I double-checked with this bit of code:

    pub run_test() | byte a[4], x, y
    
      bytefill(@a, 0, 4)                                            ' clear array to start
    
      repeat x from 0 to 3
        a[x] := $1234
        repeat y from 0 to 3
          term.fxhex(a[y], 2)
          term.tx(" ")
        term.tx(13)
    

    This was the output:

  • Thanks, that's great!

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