= MWMR  =

== General presentation ==

The MWMR communication middleware implements a generic inter-task communication mechanism for
shared memory multi-processors architectures. This protocol has been designed to support both
communication between ''software tasks'' (running on a programmable processor), and ''hardware tasks'',
implemented as dedicated hardware coprocessors. 

MWMR stands for ''Multi Writers, Multi-Readers''. The MWMR channel itself is implemented as a software
FIFO, that can have several producers, and several consumers. Each MWMR communication channel
is protected by a dedicated ''lock'', for exclusive access.

Any access to a shared MWMR channel respect the following five stages protocol :
 * get the lock protecting the MWMR (READ/WRITE access).  
 * test the status of the MWMR (READ access).
 * transfer a burst of data between a local buffer and the MWMR (READ/WRITE access). 
 * update the status of the MWMR (WRITE access). 
 * release the lock (WRITE access).

The MWMR middleware can be used with both the MutekH and MutekS operating systems.

== More Information ==

The MWMR middleware has two main components :
 * The software part is a library of C functions. Those functions are build on top of the POSIX API and implement the 5 steps MWMR protocol. They can be used by a software task to read from( or write into) one or several MWMR channels. The code is a [http://www.mutekh.org/ MutekH] library available [mutekh:source:/trunk/mutekh/libmwmr as libmwmr]
 * The  hardware part is a generic [wiki:Component/VciMwmrController MWMR controller]. This hardware component has a DMA capability, and implement the 5 steps MWMR protocol. It and can be used by any hardware coprocessor that has one or several simple FIFO interfaces.