Testing bits of a byte

[Jon Chandler]

I'm reading 8 input pins on an I2C port expander. The data is read out as a byte. I'm testing the status of each bit with 8 IF/THEN statements testing VARIABLE.BITS(n).

I should be able to do the same thing with a mask and a logical AND, but it's still 8 IF/THEN statements but this still doesn't seem very efficient.

The 8 inputs are independent and there's separate action to take depending on each pin.

Am I missing some easy way of doing this?

Thanks for any ideas.

[Jerry Messina]

The 8 inputs are independent and there's separate action to take depending on each pin.

Syntactically there's a couple of ways if doing this, but since in the end you need to handle 8 different conditions I don't think there's any real shortcut.

As long as the 'bits(x)' part has a const for 'x', like

Code: Select all

if (variable.bits(0) = 1) then
  <stuff>
endif
if (variable.bits(1) = 1) then
  <stuff>
endif
etc

then the code is about as short as it's going to get. If you had a variable in there for the bit index then things get a lot worse.

[Jon Chandler]

Thanks Jerry. Just wanted to make sure I wasn't overlooking some simple method!