Function:     GGIDRV

Purpose:      Driver for exported Ggi plotfields.

Category:     GRAPHICS

File:         pgdriv.src

Author:       J.P. Terlouw

Use:          CALL GGIDRV( IDEV ,     Input/Output    INTEGER
                           IFUNC ,       Input        INTEGER
                           RBUF ,     Input/Output    REAL ARRAY
                           NBUF ,     Input/Output    INTEGER
                           CHR ,      Input/Output    CHARACTER*(*)
                           LCHR )     Input/Output    INTEGER

              IDEV       Device identifier.
              IFUNC      Operation code which specifies what operation
                         the device handler is to perform. (see the
                         programmers guide.)
              RBUF       Floating-point array used to pass numerical
                         data to or from the device handler.
              NBUF       Indicates how many elements of RBUF are used.
              CHR        Used to pass character data to or from the
                         device handler.
              LCHR       Indicates how many characters are used.

Description:  In normal operation, this driver attempts to connect to
              a socket in the directory $HOME/.gipsy/ggidevices/
              with the same name as the device name.
              If the device name is "SCREEN", it attempts to connect
              with the socket $HOME/.gipsy/ggidevices/PGVIEW:0 and if
              this fails, tries to start PGVIEW to create this socket.

Updates:      Aug 11, 2004: JPT Document created.
              Mar  7, 2009: JPT Bugfix: zero byte missing from device name.
              May 18, 2012: JPT Implemented special device "SCREEN".