IS_USED
s->key = IS_USED | IS_CTL7 | (chan << 7) | key;
s->key = (c << 20) | (chan << 16) | IS_USED | key;
if ( !(s->table[s->idx] & IS_USED) )
if ( !(orig & IS_USED) ) {
if ( !(val & IS_USED) )
if (!(s->table[oidx] & IS_USED))