Intel 386 - Manual (Page 328)

11-41
ASYNCHRONOUS SERIAL I/O UNIT
}
} /* SerialWriteMem */
/*****************************************************************************
Serial0_ISR:
Description:
Template Interrupt Service Routine for Serial Port0 interrupts.
This function identifies the cause of the interrupt and branches
to the corresponding action.
Parameters:
None (Not called by user)
Returns:
None
Assumptions:
None
Syntax:
Not a user function.
Real/Protected Mode:
No changes required.
******************************************************************************/
void interrupt far Serial0_ISR (void)
{
BYTE iir0, lsr0, msr0;
iir0 = _GetEXRegByte(IIR0);
switch ((iir0&0x06) >> 1) {
case 0:
/* modem status signal */
msr0 = _GetEXRegByte(MSR0);
if ((msr0&0x08) && (msr0&0x80)){
/* data carrier detect has been set */
}