// this is for +Fs/4 [moves receive frequency to the left in the spectrum display]
for (unsigned i = 0; i < BUFFER_SIZE * N_BLOCKS; i += 4)
{ // float_buffer_L contains I = real values
// float_buffer_R contains Q = imaginary values
// xnew(0) = xreal(0) + jximag(0)
// leave as it is!
// xnew(1) = - ximag(1) + jxreal(1)
hh1 = - float_buffer_R[i + 1];
hh2 = float_buffer_L[i + 1];
float_buffer_L[i + 1] = hh1;
float_buffer_R[i + 1] = hh2;
// xnew(2) = -xreal(2) - jximag(2)
hh1 = - float_buffer_L[i + 2];
hh2 = - float_buffer_R[i + 2];
float_buffer_L[i + 2] = hh1;
float_buffer_R[i + 2] = hh2;
// xnew(3) = + ximag(3) - jxreal(3)
hh1 = float_buffer_R[i + 3];
hh2 = - float_buffer_L[i + 3];
float_buffer_L[i + 3] = hh1;
float_buffer_R[i + 3] = hh2;
}