How to set the UART's Divisor Register in NT using API

[Roy Wang]

I have a question about how to change the Divisor Latch in the serial port. In win98, _inp() and _outp() can work, but in NT it don't work. The source is as following:
unsigned char result;
unsigned short ppport = 0x2EB;

result = _inp( ppport );
_outp( ppport, (result | 0x80));
_outp( 0x2E8, 21 );
_outp( 0x2E9, 0x00 );
_outp( 0x2EB, (result & 0x7F));

Roy Wang