unsigned CLASS getbithuff (int nbits, ushort *huff)
{
  int c;

  if (nbits == -1)
    return bitbuf = vbits = reset = 0;
  if (nbits == 0 || vbits < 0) return 0;
  while (!reset && vbits < nbits && (c = fgetc(ifp)) != EOF &&
    !(reset = zero_after_ff && c == 0xff && fgetc(ifp))) {
    bitbuf = (bitbuf << 8) + (uchar) c;
    vbits += 8;
  }
  c = bitbuf << (32-vbits) >> (32-nbits);
  if (huff) {
    vbits -= huff[c] >> 8;
    c = (uchar) huff[c];
  } else
    vbits -= nbits;
  if (vbits < 0) derror();
  return c;
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.