SIOCOPYSIZE
uint8_t buf[SIOCOPYSIZE];
if (incc > SIOCOPYSIZE) {
bcopy(com->ibuf, buf, SIOCOPYSIZE);
bcopy(com->ibuf + SIOCOPYSIZE, com->ibuf, incc - SIOCOPYSIZE);
com->iptr = com->ibuf + incc - SIOCOPYSIZE;
incc = SIOCOPYSIZE;