= Functional Description =

This VCI target is a memory mapped peripheral implementing
a vectorized interrupt controller. It can concentrate up 
to 32 independent interrupt lines '''p_irq_in[i]''' to a single 
'''p_irq''' interrupt line.
The active state is high, and the output interrupt is the logical OR of all 
input interrupts. 
Each input interrupt can be individually masked
using a memory mapped  32 bits register.
This component can be addresse to return the index of the highest priority
active interrupt '''p_irq_[i]'''. 
The priority scheme is fixed : The lower indexes have the highest priority.
The memory segment allocated to this component must be aligned
on 8 bytes boundary.
This hardware component cheks for segmentation violation, and can be used
as a default target.

This component contains 2 memory mapped registers:

 * '''ICU_INDEX'''     : ADDRESS![2:0] = 0x0
It is actually a 32 bits pseudo-register: A read request
returns the index value of the highest priority active input interrupt.
If there is no active interrupt, it returns the 32 value.
This register is read-only.

 * '''ICU_MASK''' : ADDRESS![2:0] = 0x4 
Each bit i of this 32 bits register enables the corresponding 
'''p_irq_in[i]''' input interrupt, when this bit is one.
This register can be read or written.A write request of a zero gives resets this register.
This register is write-only.

= CABA  Implementation =

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

== Template parameters: ==
 * The VCI parameters

== Constructor parameters ==
{{{ 
VciIcu(
     sc_module_name name,  // Component Name
     const soclib::common::InTab &index, // Target index
     const soclib::common::MappingTable &mt,  // Mapping Table
     size_t nirq);  // Number of input interrupts
}}}

== Ports ==
 * sc_in<bool> p_resetn  : Global system reset
 * sc_in<bool> p_clk : Global system clock
 * soclib::caba::VciTarget<vci_param> p_vci : VCI port
 * sc_out<bool> p_irq : Output interrupt port
 * sc_in<bool> *p_irq_in : pointer to the input interrupts ports table