FSE_GETSYMBOL
op[0] = FSE_GETSYMBOL(&state1);
op[1] = FSE_GETSYMBOL(&state2);
op[2] = FSE_GETSYMBOL(&state1);
op[3] = FSE_GETSYMBOL(&state2);
*op++ = FSE_GETSYMBOL(&state1);
*op++ = FSE_GETSYMBOL(&state2);
*op++ = FSE_GETSYMBOL(&state2);
*op++ = FSE_GETSYMBOL(&state1);