= Description =

[[Image(VciLocks.png, align=right)]]

This VCI target is an hardware semaphore helper.

VCI-based systems may have some difficulties implementing proper locking of target components
as this can be done on buses. As a side-effect, locks and other atomic-access-based
software resources can't be used. This component solves this problem implementing the
atomic-access-like features on target side.

This components has one bit of information stored on each 32-bit addressable word:
 * When read, its current value is returned, and it is implicitly set to 1
 * When written to, it is reset to 0.

This way:
 * A spin lock is a simple loop waiting to read 0
 * Releasing the lock is a simple write operation

= Implementations =

== Caba implementation ==

The caba implementation is in 
 * source:trunk/soclib/systemc/include/caba/target/vci_locks.h
 * source:trunk/soclib/systemc/src/caba/target/vci_locks.cc

Template parameters:
 * The VCI parameters

Instanciation parameters
 * Name
 * Target's index
 * MappingTable reference

Ports
 * p_vci: the VCI port
 * p_resetn: Global system reset
 * p_clk: Global system clock