94 lines
2.9 KiB
C++
94 lines
2.9 KiB
C++
/*
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* Copyright (c) 1999-2010 Stephen Williams (steve@icarus.com)
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*
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* This source code is free software; you can redistribute it
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* and/or modify it in source code form under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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# include "config.h"
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# include "netlist.h"
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# include "netmisc.h"
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/*
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* This function transforms an expression by padding the high bits
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* with V0 until the expression has the desired width. This may mean
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* not transforming the expression at all, if it is already wide
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* enough.
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*/
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NetExpr*pad_to_width(NetExpr*expr, unsigned wid)
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{
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if (wid <= expr->expr_width())
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return expr;
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/* If the expression is a const, then replace it with a wider
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const. This is a more efficient result. */
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if (NetEConst*tmp = dynamic_cast<NetEConst*>(expr)) {
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verinum eval = tmp->value();
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bool signed_flag = eval.has_sign();
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verinum::V pad = verinum::V0;
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if (signed_flag)
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pad = eval.get(eval.len()-1);
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verinum oval (pad, wid, eval.has_len());
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for (unsigned idx = 0 ; idx < eval.len() ; idx += 1)
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oval.set(idx, eval.get(idx));
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oval.has_sign(signed_flag);
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tmp = new NetEConst(oval);
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delete expr;
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return tmp;
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}
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/* Do it the hard way, with a concatenation. */
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verinum pad(verinum::V0, wid - expr->expr_width());
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NetEConst*co = new NetEConst(pad);
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co->set_line(*expr);
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NetEConcat*cc = new NetEConcat(2);
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cc->set_line(*expr);
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cc->set(0, co);
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cc->set(1, expr);
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cc->set_width(wid);
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expr = cc;
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return expr;
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}
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NetNet*pad_to_width(Design*des, NetNet*net, unsigned wid)
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{
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NetScope*scope = net->scope();
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const string path = scope->name();
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assert(scope);
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if (net->pin_count() >= wid)
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return net;
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verinum pad(verinum::V0, wid - net->pin_count());
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NetConst*con = new NetConst(scope, scope->local_symbol(), pad);
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des->add_node(con);
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NetNet*tmp = new NetNet(scope, scope->local_symbol(),
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NetNet::WIRE, wid);
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tmp->local_flag(true);
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for (unsigned idx = 0 ; idx < net->pin_count() ; idx += 1)
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connect(tmp->pin(idx), net->pin(idx));
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for (unsigned idx = net->pin_count() ; idx < wid ; idx += 1)
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connect(tmp->pin(idx), con->pin(idx-net->pin_count()));
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return tmp;
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}
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