int JBIG2MMRDecoder::getWhiteCode() {
  const CCITTCode *p;
  Guint code;

  if (bufLen == 0) {
    buf = str->getChar() & 0xff;
    bufLen = 8;
    ++nBytesRead;
  }
  while (1) {
    if (bufLen >= 11 && ((buf >> (bufLen - 7)) & 0x7f) == 0) {
      if (bufLen <= 12) {
	code = buf << (12 - bufLen);
      } else {
	code = buf >> (bufLen - 12);
      }
      p = &whiteTab1[code & 0x1f];
    } else {
      if (bufLen <= 9) {
	code = buf << (9 - bufLen);
      } else {
	code = buf >> (bufLen - 9);
      }
      p = &whiteTab2[code & 0x1ff];
    }
    if (p->bits > 0 && p->bits <= (int)bufLen) {
      bufLen -= p->bits;
      return p->n;
    }
    if (bufLen >= 12) {
      break;
    }
    buf = (buf << 8) | (str->getChar() & 0xff);
    bufLen += 8;
    ++nBytesRead;
  }
  error(str->getPos(), "Bad white code in JBIG2 MMR stream");
  --bufLen;
  return 1;
}

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