suggested wording for message ordering

Location: pdf page 37, page #28

Add a subsection on message ordering

The idea of ordering message delivery to software arises from the fact
that there is a global time order defined in the HDL domain by the order
of cclock edges. The delivery of messages to software respects this
ordering. In particular, the delivery of messages from hardware to
software is ordered using the following rules:

Messages from a single message out port are delivered to software in the
same time order in which they are delivered to the port.

Messages from different ports which are initiated by the dual-ready
protocol on different cclocks are delivered to software in the time
order in which they were presented.

In the case that two message ports accomplish the dual-ready protocol
and have data move in the same cclock cycle, the order of delivery of
the messages to the software is undefined.

Location: pdf page 61 , page 53

Since there is no global time on the software side, the ordering of
messages from software to hardware must be accomplished by some other
principle. The principle used is wall-clock time. Messages sent from
the software to the HDL side are delivered in the order that the send
functions are called. In a multithreaded or multiprocessor
environment this requires the user to ensure the ordering of messages
between threads or processors if this order is consequential. This
can be accomplished using the mutex or semaphore constructs that all
such environments provide.

In particular, messages are delivered to the hardware side in the order
that the SceMiMessageInPortProxy::Send() calls are made. This implies
that within any single thread, messages are delivered in order, but
between threads ordering is undefined unless the user coordinates the
order of calls.

Duaine

 
Received on Thu Sep 9 14:24:38 2004