[wiki:Component SocLib Components General Index] 

= !VciLocks =

== 1) Functional Description ==

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

This VCI target is a locks controller : In VCI-based systems, it is not anymore possible
to "lock the bus" to implement the atomic ''test & set'' instructions used for software synchronisation.
Therefore, this memory mapped hardware peripheral implements a set of binary locks:
 * Each binary lock is a single flip-flop, but corresponds to 4 bytes in the address space. The segment allocated to this component must be aligned on a 4 bytes boundary. The number of available locks is defined by segment_size / 4.
 * Any read request is interpreted as a ''test & set'' operation : the value stored in the addressed flip-flop is returned, and the addressed flip-flop is set to 1.
 * All write request are interpreted as ''reset'' : the addressed flip-flop is reset to 0.
This way, a spin lock is implemented as a simple loop waiting to read 0, and the lock release is a simple write operation.
This components checks addresses for segmentation violation, and can be used as default target.

== 2) Component definition & usage ==

source:trunk/soclib/soclib/module/internal_component/vci_locks/caba/metadata/vci_locks.sd

See [wiki:SoclibCc/VciParameters SoclibCc/VciParameters]
{{{
Uses( 'vci_locks', **vci_parameters )
}}}

== 3) CABA  Implementation ==

=== CABA sources ===
 
 * interface : source:trunk/soclib/soclib/module/internal_component/vci_locks/caba/source/include/vci_locks.h
 * implementation : source:trunk/soclib/soclib/module/internal_component/vci_locks/caba/source/src/vci_locks.cpp

=== CABA Constructor parameters ===
{{{
VciLocks(
     sc_module_name name,   // Instance name
     const soclib::common::IntTab &index,   //  Target index
     const soclib::common::MappingTable &mt);   // Mapping Table
}}}

=== CABA Ports ===

 * sc_in<bool> '''p_resetn''' : Global system reset
 * sc_in<bool> '''p_clk''' : Global system clock
 * soclib::caba::!VciTarget<vci_param> '''p_vci''' : The VCI port

== 4) TLM-T implementation ==

=== TLM-T sources ===
 
 * interface : source:trunk/soclib/soclib/module/internal_component/vci_locks/tlmt/source/include/vci_locks.h
 * implementation : source:trunk/soclib/soclib/module/internal_component/vci_locks/tlmt/source/src/vci_locks.cpp

=== TLM-T Constructor parameters ===
{{{
VciLocks(
     sc_module_name name,   // Instance name
     const soclib::common::IntTab &index,   //  Target index
     const soclib::common::MappingTable &mt);   // Mapping Table
}}}

=== TLM-T Ports ===

 * soclib::tlmt::!VciTarget<vci_param> '''p_vci''' : The VCI port