14-bit left-justified two's complement to a signed short

问题

I have two bytes containing a 14-bit left-justified two's complement value, and I need to convert it to a signed short value (ranging from -8192 to +8191, I guess?)

What would be the fastest way to do that?

回答1:

Simply divide by 4.

(Note, right-shift leads to implementation/undefined behaviour.)

回答2:

A portable solution:

short convert(unsigned char hi, unsigned char lo)
{
  int s = (hi << 6) | (lo >> 2);
  if (s >= 8192)
    s -= 16384;
  return s;
}

来源：https://stackoverflow.com/questions/14710764/14-bit-left-justified-twos-complement-to-a-signed-short