How to read radio audio switches

[Abdullah Radwan]

Hi,

I am using C++ SDK. I am not familiar with bits system. I want to read radio audio switches (offset 3122). Could somebody provide an example?

I want to check which com is selected.

[Abdullah Radwan]

After playing a lot, here is working code:

byte audioSelection;

FSUIPC_Read(0x3122, 1, &audioSelection, &error);
int comSelection = 0;
if(audioSelection >= 128) comSelection = 1; //Com 1
else comSelection = 2; //Com 2

 

[Pete Dowson]

1 hour ago, Abdullah Radwan said:

After playing a lot, here is working code:

Well done. But in general, when you want to test one "bit" in a byte, you'd use:

if (x & mask) ...

where x is the value you've read, and "mask" is the value of the bit( you want to test for. So in your case:

if (audioSelection & 128)
  for COM1, and

if (audioSelection & 64)
  for COM2

There are other bits for the other audio switches.

Bit values are derived from evaluation 2 to the power n, i.e. 2 times 2 'n' number of times, with the special-seeming case that 0 results always in the value 1. So:

bit 0 = 1
bit 1 = 2
bit 2 = 4
bit 3 = 8
bit 4 = 16
bit 5 = 32
bit 6 = 64
bit 7 = 128

For more about bits, see the FAQ subforum help thread entitled
About bits, numbers and hexadecimal

Pete

 

[Abdullah Radwan]

Thank you so much! This what I need. Thanks for pointing out the correct way.