Android Question Convert -64 (signed) to 192(unsigned)

mscientist33 · Mar 28, 2022

I am getting a byte which should be 192, b4a takes it as a signed byte of -64. How can I use it as unsigned as get my 192?

Brian Dean · Mar 28, 2022

B4X:

    Dim b as byte
    Dim i as int
    ....
    ...
    If (b < 0) Then i = b + 256 Else i = b

emexes · Mar 28, 2022

Unsigned Bytes would be great, although I suspect they'd be implemented as Java Ints or Shorts.

B4X:

Dim b As Byte = Rnd(-127, 0)

Dim OneWay As Int = Bit.And(b, 0xFF)

Dim AnotherWay As Int = b Mod 256

Log(b)
Log(OneWay)
Log(AnotherWay)

emexes · Mar 29, 2022

If you're calculating a packet checkvalue by summing packet bytes, you can leave the signed-to-unsigned adjustment until the end.

And if the packet checkvalue and your summing variable are both Bytes, then you probably don't even need to do an adjustment at all, because they'll both be subject to the same -128..127 range wraparound.

mscientist33 · Mar 30, 2022

Ah, I found my problem. I was doing your "oneway" example but I was still declaring a byte instead of an int....

Android Question Convert -64 (signed) to 192(unsigned)

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Android Question Convert -64 (signed) to 192(unsigned)

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