MOUSE(3)                                                 MOUSE(3)

          mouse, cursor - kernel mouse interface

          bind -a #m /dev


          The mouse device provides an interface to the mouse.  There
          is also a cursor associated with the screen; it is always
          displayed at the current mouse position.

          Reading the mouse file returns the mouse status: its posi-
          tion and button state.  The read blocks until the state has
          changed since the last read.  The read returns 49 bytes: the
          letter m followed by four decimal strings, each 11 charac-
          ters wide followed by a blank: x and y, coordinates of the
          mouse position in the screen image; buttons, a bitmask with
          the 1, 2, and 4 bits set when the mouse's left, middle, and
          right buttons, respectively, are down; and msec, a time
          stamp, in units of milliseconds.

          Writing the mouse file, in the same format, causes the mouse
          cursor to move to the position specified by the x and y
          coordinates of the message.  The buttons and msec fields are
          ignored and may be omitted.

          Writes to the mousein file are processed as if they were
          generated by the mouse hardware itself, as extra mouse
          events to be processed and passed back via the mouse file.
          The mousein file, which is exclusive-use and may be opened
          only by the host owner, is intended for controlling devices,
          such as USB mice, that are managed by user-level software.
          Each event should consist of the letter m followed by delta
          x, delta y, and buttons as space-separated decimal numbers.

          Writing to the mousectl file configures and controls the
          mouse.  The messages are:

          serial n         sets serial port n to be the mouse port.
          ps2              sets the PS2 port to be the mouse port.
          intellimouse     uses the wheel on a Microsoft Intellimouse
                           as the middle button.
          ps2intellimouse  is equivalent to a write of ps2 followed by
                           a write of intellimouse.
          accelerated [n]  turns on mouse acceleration.  N is an

     Page 1                       Plan 9             (printed 7/23/24)

     MOUSE(3)                                                 MOUSE(3)

                           optional acceleration factor.
          linear           turns off mouse acceleration.
          res n            sets mouse resolution to a setting between
                           0 and 3 inclusive.
          hwaccel on/off   sets whether acceleration is done in hard-
                           ware or software.  By default, PS2 mice use
                           hardware and serial mice use software.
                           Some laptops (notably the IBM Thinkpad T23)
                           don't implement hardware acceleration for
                           external mice.
          swap             swaps the left and right buttons on the
          buttonmap xyz    numbers the left, middle, and right mouse
                           buttons x, y, and z, respectively.  If xyz
                           is omitted, the default map, 123, is used.
                           Thus in the default state writing buttonmap
                           321 swaps left and right buttons and writ-
                           ing buttonmap 123 or just buttonmap
                           restores their usual meaning.  Note that
                           buttonmap messages are idempotent, unlike
          reset            clears the mouse to its default state.
          blank            Blank the screen.  The screen also blanks
                           after 30 minutes of inactivity.  The screen
                           can be unblanked by moving the mouse.
          blanktime minutes
                           Set the timeout before the screen blanks;
                           the default is 30 minutes.  If minutes is
                           zero, blanking is disabled.
          twitch           unblanks the screen and resets the idle
                           timeout as if the mouse was twitched.

          Not all mice interpret all messages; with some devices, some
          of the messages may be no-ops.

          Cursors are described in graphics(2). When read or written
          from or to the cursor file, they are represented in a 72-
          byte binary format.  The first and second four bytes are
          little endian 32-bit numbers specifying the x and y coordi-
          nates of the cursor offset; the next 32 bytes are the clr
          bitmask, and the last 32 bytes the set bitmask.

          Reading from the cursor file returns the current cursor
          information.  Writing to the cursor file sets the current
          cursor information.  A write of fewer than 72 bytes sets the
          cursor to the default, an arrow.

          The mouse and cursor files are multiplexed by rio(1) to give
          the illusion of a private mouse to each of its clients.  The
          semantics are otherwise the same except that notification of
          a window resize is passed to the application using a mouse
          message beginning with r rather than m; see rio(4) for

     Page 2                       Plan 9             (printed 7/23/24)

     MOUSE(3)                                                 MOUSE(3)


          To cope with pointing devices with only two buttons, when
          the shift key is pressed, the right mouse button generates
          middle-button events.



          The cursor format is big endian while the rest of the graph-
          ics interface is little endian.

     Page 3                       Plan 9             (printed 7/23/24)