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// $Id: wavefront.cpp 5262 2012-09-20 23:39:40Z 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.
*/
/*wavefront.cpp
*
*The wave front allocator
*
*/
#include "booksim.hpp"
#include "wavefront.hpp"
Wavefront::Wavefront( Module *parent, const string& name,
int inputs, int outputs, bool skip_diags ) :
DenseAllocator( parent, name, inputs, outputs ),
_last_in(-1), _last_out(-1), _skip_diags(skip_diags),
_square(max(inputs, outputs)), _pri(0), _num_requests(0)
{
}
void Wavefront::AddRequest( int in, int out, int label,
int in_pri, int out_pri )
{
DenseAllocator::AddRequest(in, out, label, in_pri, out_pri);
_num_requests++;
_last_in = in;
_last_out = out;
_priorities.insert(make_pair(out_pri, in_pri));
}
void Wavefront::Allocate( )
{
int first_diag = -1;
if(_num_requests == 0)
// bypass allocator completely if there were no requests
return;
if(_num_requests == 1) {
// if we only had a single request, we can immediately grant it
_inmatch[_last_in] = _last_out;
_outmatch[_last_out] = _last_in;
first_diag = _last_in + _last_out;
} else {
// otherwise we have to loop through the diagonals of request matrix
for(set<pair<int, int> >::const_reverse_iterator iter =
_priorities.rbegin();
iter != _priorities.rend(); ++iter) {
for ( int p = 0; p < _square; ++p ) {
for ( int output = 0; output < _square; ++output ) {
int input = ( ( _pri + p ) + ( _square - output ) ) % _square;
if ( ( input < _inputs ) && ( output < _outputs ) &&
( _inmatch[input] == -1 ) && ( _outmatch[output] == -1 ) &&
( _request[input][output].label != -1 ) &&
( _request[input][output].in_pri == iter->second ) &&
( _request[input][output].out_pri == iter->first ) ) {
// Grant!
_inmatch[input] = output;
_outmatch[output] = input;
if(first_diag < 0) {
first_diag = input + output;
}
}
}
}
}
}
_num_requests = 0;
_last_in = -1;
_last_out = -1;
_priorities.clear();
assert(first_diag >= 0);
// Round-robin the priority diagonal
_pri = ( ( _skip_diags ? first_diag : _pri ) + 1 ) % _square;
}
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