Keep sign when using bitsliceget()

Hi there,

I want to extract 8 bits from a 16bit fixed point number using bitsliceget(). Unfortunately the result is always an unsigned variable, which is not what I want.

Here is a little example:

x = fi(-0.12835,true, 16,10);
x.bin
  ans = 1111111101111101

y = bitsliceget(x,9,2)
  ans = 190
  DataTypeMode: Fixed-point: binary point scaling
  Signedness: Unsigned
  WordLength: 8
  FractionLength: 0
y.bin
  ans = 10111110

bitsliceget(x,9,2) actually does exactly what I want it to but I just can't get y to become a signed variable without recasting and therefore changing the binary representation.

Any help would be highly appreciated.

Thanks it advance for taking the time!

Regards,

Len

Answer 1

[Krishnan Gopal]

Hi

The result of bitsliceget is always interpreted as an unsigned type, so you can use the 'reinterpretcast' function to re-evaluate it as a numeric signed type. In your case, the you should cast it to a signed numerictype with 8 bits as shown:

y = reinterpretcast(bitsliceget(x,9,2), numerictype(1,8,0));

regards

Krishnan