mkttydata: Build cache for termcap/graphcap device entries

Package: softools

Usage

mkttydata devices termcap_file output_file

Parameters

devlist: A comma delimited list of the devices whose termcap or graphcap entries are to be compiled.

termcap_file: The name of the termcap or graphcap file be searched, e.g., "dev$termcap", or "dev$graphcap".

output_file: The name of the output file to be written, an SPP include file containing a number of declarations and data initialization statements. This should be "dev$cachet.dat" if the standard termcap is being compiled, and "dev$cacheg.dat" if the standard graphcap is being compiled.

verbose = yes: Causes a message to be printed for each device entry compiled.

Description

The mkttydata task is used by the IRAF system manager to precompile the termcap or graphcap entries for commonly used video or graphics terminals. This can be advantageous on slow systems since otherwise the termcap or graphcap file must be searched at runtime every time the screen is cleared or a graph is plotted, reducing the performance and interactive response of the system. Since each IRAF site will commonly use a different set of devices, entries can only be cached by the local system manager after the system is installed. [NOTE, Jun 1990: the above is still true, but with the addition of features such as shared libraries and multiple architecture support to some versions of IRAF, relinking IRAF is more difficult and it is easier to make mistakes. Furthermore, modern systems are getting very fast. For most sites it will be easier, and safer, to merely copy frequently referenced device entries to the head of the termcap or graphcap file and skip the sysgen.]

The input to mkttydata consists of a list of devices and a reference to either the termcap or graphcap file. The output is an SPP include file which is referenced by the procedures in the TTY package. After updating the cache files, a full system sysgen is required to recompile the affected modules, update them in the system libraries, and relink all executables.

Enter the following values for the termcap_file and output_file parameters to build the termcap and graphcap cache files. Note that for caching to work the value of termcap_file must match that of the termcap or graphcap environment variable, hence do not enter "graphcap" rather than "dev$graphcap", just because you happen to be in the dev directory.

                termcap_file     output_file

termcap         dev$termcap     dev$cachet.dat
graphcap        dev$graphcap    dev$cacheg.dat

After updating these files, perform a sysgen-relink to update the system libraries and relink all executables (this takes a while, and requires IRAF permissions and full sources). Instructions for performing the sysgen-relink are given in the Site Manager's Guide for your IRAF system. The exact procedure for performing a sysgen-relink depends upon the host system. In particular, if the system support multiple architectures, each architecture must be restored and relinked separately. Note that systems configured for multiple architecture support are shipped configured "generic", and you must restore an architecture before relinking or the entire IRAF system will be recompiled (which is time consuming, and inadvisable due to the possibility of system or compiler differences introducing bugs into IRAF).

After this finishes, log out and back in and you should notice the difference when running tasks like page, clear, and implot.

Note that once a device entry is cached it cannot be modified without going through this all over again, while if the entry is not cached it can be edited and the new entry used immediately. It is therefore not desirable to cache new termcap or graphcap entries until they have stopped changing. Even after a device entry has been cached, however, it is possible to test new entries by changing the entry name, or by changing the value of the termcap or graphcap environment variable. If these values are different than they were when the entries were cached, the cached entries will not be used, even if the device name matches that of a cached entry.

For additional information on graphcap see the "GIO Design" document. For additional information on termcap see the Berkeley UNIX "Programmer's Guide: Reference Manual", section 5. IRAF uses a standard UNIX termcap.

Examples

1. Update the graphcap cache.

cl> mktty vt640,vt240,4012,cit414a dev$graphcap dev$cacheg.dat

Bugs

There is a fixed limit on the amount of data that can be cached. If the limit is exceedd the affected TTY modules will fail to compile.