RMWx Commands

RMWx (Read/Modify/Write) commands are available in byte format (indexed or 
nonindexed) and in word format (nonindexed). A nonindexed port RMWx can be 
used for ports that have different read and write access I/O addresses. 
The syntax is as follows: 

RMWBI( indexport, dataport, index, andmask, ormask );
RMWB( bytereadport, bytewriteport, andmask, ormask );
RMWW( wordreadport, wordwriteport, andmask, ormask );

<indexport>  ::= <pio variable>  |  <constant>
<dataport>  ::= <pio variable>  |  <constant>
<bytereadport>  ::= <pio variable>  |  <constant>
<bytewriteport>  ::= <pio variable>  |  <constant>
<wordreadport>  ::= <pio variable>  |  <constant>
<wordwriteport>  ::= <pio variable>  |  <constant>
<index>  ::= <constant>
<andmask>  ::= <constant>
<ormask>  ::= <constant>

For example: 

rmww(0x4ae8, 0x4ae8, 0x01, 0x00);