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     INW(K)                    UNIX System V                    INW(K)



     Name
          inw, outw - reads, writes a 16-bit word from or to a
          physical I/O address

     Syntax
          int
          inw(read_addr)
          int read_addr;

          int
          outw (write_addr, value)
          int write_addr, value;

     Description
          The inw function reads a 16-bit word from the physical I/O
          address specified by read_addr.  outw writes a 16-bit word
          to the physical I/O address specified by write_addr.

     Warning
          If the specified read or write address is above 0x1000, call
          flushtlb(K) before calling inw or outw.  Refer to the
          flushtlb manual page for more information.

     Parameters
          read_addr is an integer that specifies the physical I/O
          address to be read from.

          write_addr is the physical I/O address being written to.
          value is the 16-bit word bring written to write_addr.

     Return
          A 32-bit integer whose high 2 bytes are set to zero is
          returned by inw. outw has no return value.

     Example
          To read a 16-bit register at I/O address 0x300 you could use
          the following lines of code:

          short int val;
          val = (short int) inw(0x300);

          To write the 16-bit value 0xFF0 to I/O address 0x300 you
          could use the following code:

          outw(0x300, 0xFF0);

     See Also
          flushtlb(K), inb(K), ind(K), repinsb(K), copyin(K)


                                                      (printed 7/19/89)