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// $Id: islip.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 <iostream>
#include "islip.hpp"
#include "random_utils.hpp"
//#define DEBUG_ISLIP
iSLIP_Sparse::iSLIP_Sparse( Module *parent, const string& name,
int inputs, int outputs, int iters ) :
SparseAllocator( parent, name, inputs, outputs ),
_iSLIP_iter(iters)
{
_gptrs.resize(_outputs, 0);
_aptrs.resize(_inputs, 0);
}
void iSLIP_Sparse::Allocate( )
{
int input;
int output;
int input_offset;
int output_offset;
map<int, sRequest>::iterator p;
bool wrapped;
for ( int iter = 0; iter < _iSLIP_iter; ++iter ) {
// Grant phase
vector<int> grants(_outputs, -1);
for ( output = 0; output < _outputs; ++output ) {
// Skip loop if there are no requests
// or the output is already matched
if ( ( _out_req[output].empty( ) ) ||
( _outmatch[output] != -1 ) ) {
continue;
}
// A round-robin arbiter between input requests
input_offset = _gptrs[output];
p = _out_req[output].begin( );
while( ( p != _out_req[output].end( ) ) &&
( p->second.port < input_offset ) ) {
p++;
}
wrapped = false;
while( (!wrapped) ||
( ( p != _out_req[output].end( ) ) &&
( p->second.port < input_offset ) ) ) {
if ( p == _out_req[output].end( ) ) {
if ( wrapped ) { break; }
// p is valid here because empty lists
// are skipped (above)
p = _out_req[output].begin( );
wrapped = true;
}
input = p->second.port;
// we know the output is free (above) and
// if the input is free, grant request
if ( _inmatch[input] == -1 ) {
grants[output] = input;
break;
}
p++;
}
}
#ifdef DEBUG_ISLIP
cout << "grants: ";
for ( int i = 0; i < _outputs; ++i ) {
cout << grants[i] << " ";
}
cout << endl;
cout << "aptrs: ";
for ( int i = 0; i < _inputs; ++i ) {
cout << _aptrs[i] << " ";
}
cout << endl;
#endif
// Accept phase
for ( input = 0; input < _inputs; ++input ) {
if ( _in_req[input].empty( ) ) {
continue;
}
// A round-robin arbiter between output grants
output_offset = _aptrs[input];
p = _in_req[input].begin( );
while( ( p != _in_req[input].end( ) ) &&
( p->second.port < output_offset ) ) {
p++;
}
wrapped = false;
while( (!wrapped) ||
( ( p != _in_req[input].end( ) ) &&
( p->second.port < output_offset ) ) ) {
if ( p == _in_req[input].end( ) ) {
if ( wrapped ) { break; }
// p is valid here because empty lists
// are skipped (above)
p = _in_req[input].begin( );
wrapped = true;
}
output = p->second.port;
// we know the output is free (above) and
// if the input is free, grant request
if ( grants[output] == input ) {
// Accept
_inmatch[input] = output;
_outmatch[output] = input;
// Only update pointers if accepted during the 1st iteration
if ( iter == 0 ) {
_gptrs[output] = ( input + 1 ) % _inputs;
_aptrs[input] = ( output + 1 ) % _outputs;
}
break;
}
p++;
}
}
}
#ifdef DEBUG_ISLIP
cout << "input match: ";
for ( int i = 0; i < _inputs; ++i ) {
cout << _inmatch[i] << " ";
}
cout << endl;
cout << "output match: ";
for ( int j = 0; j < _outputs; ++j ) {
cout << _outmatch[j] << " ";
}
cout << endl;
#endif
}
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