ASY_LSR_DR
if (!(lsr & ASY_LSR_DR))
while ((lsr & (ASY_LSR_DR | ASY_LSR_ERRORS)) != 0) {
while ((lsr & (ASY_LSR_DR | ASY_LSR_ERRORS)) != 0) {
if (lsr & ASY_LSR_DR) {
return ((asy_get_reg(asy, ASY_LSR) & ASY_LSR_DR) != 0);