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Message
From: "Damon Brantley" <brantley@m...>
Date: Sun, 06 Jul 2003 18:25:55 -0500
Subject: [openrisc] Understanding traffic cop
I am to a point in my project of trying to get uclinux running on a
digilent board, where I am ready to
integrate all the hdl code pieces together. I am trying to understand how
traffic cop works so I can
prune its size down. The full traffic cop uses up a third of my gate array
space so it needs to be pruned
down some. However I am having some difficulty in understanding how it
works. There are not many
comments in the code.
A minimum setup is just getting the cpu and memory controller attached.
However I want to be able
to easily add or remove items to/from the bus as space allows.
Some of the things I am having problems with are:
1. What are the signals with names like xi0_wb_dat_o or yi0_wb_dat_o for
example.
These ultimately are getting or'ed together to produce the output
i0_wb_dat_o, but I do not understand
the separation.
2. What is target 0 and initiator 0. Are these real devices on the bus like
(cpu and memory) or is this
a reference to traffic cop itself.
3. What does the comment // From initiators to targets 1-8 (lower part) and
// From initiators to targets 1-8 (upper part)
mean?
4. What are the z signals like z_wb_cyc_i for?
Ultimately I know this is a multiplexer, but the devil is in the details.
If there are some other docs I should be
looking at, let me know.
Thanks,
Damon
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