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// $Id: prio_arb.cpp 5188 2012-08-30 00:31:31Z dub $
/*
Copyright (c) 2007-2012, Trustees of The Leland Stanford Junior University
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "booksim.hpp"
#include <cassert>
#include "prio_arb.hpp"
PriorityArbiter::PriorityArbiter( const Configuration &config,
Module *parent, const string& name,
int inputs )
: Module( parent, name ), _rr_ptr(0), _inputs( inputs )
{
}
void PriorityArbiter::Clear( )
{
_requests.clear( );
}
void PriorityArbiter::AddRequest( int in, int label, int pri )
{
sRequest r;
list<sRequest>::iterator insert_point;
r.in = in; r.label = label; r.pri = pri;
insert_point = _requests.begin( );
while( ( insert_point != _requests.end( ) ) &&
( insert_point->in < in ) ) {
insert_point++;
}
bool del = false;
bool add = true;
// For consistant behavior, delete the existing request
// if it is for the same input and has a higher
// priority
if ( ( insert_point != _requests.end( ) ) &&
( insert_point->in == in ) ) {
if ( insert_point->pri < pri ) {
del = true;
} else {
add = false;
}
}
if ( add ) {
_requests.insert( insert_point, r );
}
if ( del ) {
_requests.erase( insert_point );
}
}
void PriorityArbiter::RemoveRequest( int in, int label )
{
list<sRequest>::iterator erase_point;
erase_point = _requests.begin( );
while( ( erase_point != _requests.end( ) ) &&
( erase_point->in < in ) ) {
erase_point++;
}
assert( erase_point != _requests.end( ) );
_requests.erase( erase_point );
}
int PriorityArbiter::Match( ) const
{
return _match;
}
void PriorityArbiter::Arbitrate( )
{
list<sRequest>::iterator p;
int max_index, max_pri;
bool wrapped;
//MERGENOTE
//booksim does not have this if statement
//as far as I can tell they are identical in function
if ( _requests.begin( ) != _requests.end( ) ) {
// A round-robin arbiter between input requests
p = _requests.begin( );
while( ( p != _requests.end( ) ) &&
( p->in < _rr_ptr ) ) {
p++;
}
max_index = -1;
max_pri = 0;
wrapped = false;
while( (!wrapped) || ( p->in < _rr_ptr ) ) {
if ( p == _requests.end( ) ) {
if ( wrapped ) { break; }
// p is valid here because empty lists
// are skipped (above)
p = _requests.begin( );
wrapped = true;
}
// check if request is the highest priority so far
if ( ( p->pri > max_pri ) || ( max_index == -1 ) ) {
max_pri = p->pri;
max_index = p->in;
}
p++;
}
_match = max_index; // -1 for no match
if ( _match != -1 ) {
_rr_ptr = ( _match + 1 ) % _inputs;
}
} else {
_match = -1;
}
}
//MERGENOTE
//added update function to priorityarbiter
void PriorityArbiter::Update( )
{
_rr_ptr = ( _rr_ptr + 1 ) % _inputs;
}
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