Basic Routines

1.

LOAD_GREG (Mode)
This subroutine must be called before any other reference to GreG services. It is used to define the operating mode and to initialize the GreG vocabulary into the SIC monitor. The argument is of type Character and can be 'LIBRARY' to initialize GreG in the ``Library Only'' (no interactive SIC monitor) mode, or 'INTERACTIVE' to initialize GreG with all SIC monitor capabilities. Strings like 'LIBRARY GREG1' or 'INTERACTIVE GREG2' can be used to load only one language, although the GREG2 $\backslash$ language requires GREG1 $\backslash$ to function. This routine does not set the SIC prompt, neither the Log File which you may specify by calling routine SIC_OPT. Please refer to the SIC manual.

2.

GR_EXEC(LINE)
This is the basic routine for all plot actions. It is able to activate any GreG command exactly in the same way as if you had typed it during an interactive session. Use GR_EXEC if you do not know to which of the GreG languages it pertains, GR_EXEC1,2 or L according to the language if you know (and you should). The command line must not include the language field. The command is not written to the SIC stack, neither to the Log File.

3.

GR_ERROR()
This logical function allows error recovery. It returns the internal error status of GreG program, and clears it. If another GreG subroutine is called while an error status exist, program execution aborts.

4.

ENTER_GREG enter GreG interactive mode. The user obtains control over GreG exactly as if he was running the GreG utility. This subroutine can only be used if GreG has been initialized in ``Interactive'' mode.

5.

EXEC_GREG(LINE)
execute a command line which can be either a GreG command or a SIC command (like '@ PROC' for example). Control returns to the calling program when the command is completed successfully. If an error occurs, the current SIC error recovery action is activated before. This is usually a PAUSE which gives interactive control to the user ; control will then return to the calling program only after command EXIT (or ^Z) has been typed. Contrary to GR_EXEC, the command is written to the SIC stack, and to the Log File. ``Interactive'' mode is required.

6.

PLAY_GREG(LINE)
execute a SIC or GreG command and then leave GreG in interactive mode. This call is thus more or less equivalent to successive calls to EXEC_GREG and ENTER_GREG (there is a minor difference in case of error). Control returns to the calling program after EXIT. ``Interactive'' mode is required.

Only GR_EXEC (or its variant) and GR_ERROR are allowed in Library Mode.