Add the cadpli HOWTO.

cadpli/cadpli.txt

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+
+CADENCE PLI1 MODULES
+
+   Copyright 2003 Stephen Williams
+   $Id: cadpli.txt,v 1.1 2003/02/16 02:44:47 steve Exp $
+
+With the cadpli module, Icarus Verilog is able to load PLI1
+applications that were compiled and linked to be dynamic loaded by
+Verilog-XL or NC-Verilog. This allows Icarus Verilog users to run
+third-party modules that were compiled to interface with XL or
+NC. Obviously, this only works on the operating system that the PLI
+application was compiled to run on. For example, a Linux module can
+only be loaded and run under Linux.
+
+Icarus Verilog uses an interface module, the "cadpli" module, to
+connect the worlds. This module is installed with Icarus Verilog, and
+is invoked by the usual -m flag to iverilog or vvp. This module in
+turn scans the extended arguments, looking for +cadpli= arguments. The
+latter specify the share object and bootstrap function for running the
+module. For example, to run the module product.so, that has the
+bootstrap function "my_boot":
+
+    vvp -mcadpli a.out +cadpli=./product.so:my_boot
+
+The "-mcadpli" argument causes vvp to load the cadpli.vpl library
+module. This activates the +cadpli= argument interpreter. The
++cadpli=<module>:<boot_func> argument, then, cause vvp, through the
+cadpli module, to load the loadable PLI application, invoke the
+my_boot function to get a veriusertfs table, and scan that table to
+register the system tasks and functions exported by that object. The
+format of the +cadpli= extended argument is essentially the same as
+the +loadpli1= argument to Verilog-XL.
+
+The integration from this point is seamless. The PLI application
+hardly knows that it is being invoked by Icarus Verilog instead of
+Verilog-XL, so operates as it would otherwise.
+
+$Log: cadpli.txt,v $
+Revision 1.1  2003/02/16 02:44:47  steve
+ Add the cadpli HOWTO.
+