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/*
* Copyright (c) 1999 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT)
#ident "$Id: synth.cc,v 1.3 1999/12/01 06:06:16 steve Exp $"
#endif
/*
* The synth function searches the behavioral description for
* patterns that are known to represent LPM library components. This
* is especially interesting for the sequential components such as
* flip flops and latches. As threads are transformed into components,
* the design is rewritten.
*/
# include "functor.h"
# include "netlist.h"
/*
* This transform recognizes the following patterns:
*
* always @(posedge CLK) Q = D
* always @(negedge CLK) Q = D
*
* always @(posedge CLK) if (CE) Q = D;
* always @(negedge CLK) if (CE) Q = D;
*
* The r-value of the assignments must be identifiers (i.e. wires or
* registers) and the CE must be single-bit identifiers. The generated
* device will be wide enough to accomodate Q and D.
*/
class match_dff : public proc_match_t {
public:
match_dff(Design*d, NetProcTop*t)
: des_(d), top_(t), pclk_(0), nclk_(0), con_(0), ce_(0),
asn_(0), d_(0)
{ }
~match_dff() { }
void make_it();
private:
virtual int assign(NetAssign*);
virtual int condit(NetCondit*);
virtual int pevent(NetPEvent*);
Design*des_;
NetProcTop*top_;
NetPEvent*pclk_;
NetNEvent*nclk_;
NetCondit *con_;
NetNet*ce_;
NetAssign *asn_;
NetNet*d_;
};
int match_dff::assign(NetAssign*as)
{
if (!pclk_)
return 0;
if (asn_)
return 0;
asn_ = as;
d_ = asn_->rval()->synthesize(des_);
if (d_ == 0)
return 0;
return 1;
}
int match_dff::condit(NetCondit*co)
{
if (!pclk_)
return 0;
if (con_ || asn_)
return 0;
con_ = co;
if (con_->else_clause())
return 0;
ce_ = con_->expr()->synthesize(des_);
if (ce_ == 0)
return 0;
return con_->if_clause()->match_proc(this);
}
int match_dff::pevent(NetPEvent*pe)
{
if (pclk_ || con_ || asn_)
return 0;
pclk_ = pe;
// ... there must be a single event source, ...
svector<class NetNEvent*>*neb = pclk_->back_list();
if (neb == 0)
return 0;
if (neb->count() != 1) {
delete neb;
return 0;
}
nclk_ = (*neb)[0];
delete neb;
return pclk_->statement()->match_proc(this);
}
void match_dff::make_it()
{
NetFF*ff = new NetFF(asn_->name(), asn_->pin_count());
for (unsigned idx = 0 ; idx < ff->width() ; idx += 1) {
connect(ff->pin_Data(idx), d_->pin(idx));
connect(ff->pin_Q(idx), asn_->pin(idx));
}
connect(ff->pin_Clock(), nclk_->pin(0));
if (ce_) connect(ff->pin_Enable(), ce_->pin(0));
ff->attribute("LPM_FFType", "DFF");
if (nclk_->type() == NetNEvent::NEGEDGE)
ff->attribute("Clock:LPM_Polarity", "INVERT");
des_->add_node(ff);
}
class synth_f : public functor_t {
public:
void process(class Design*, class NetProcTop*);
private:
void proc_always_(class Design*);
NetProcTop*top_;
};
/*
* Look at a process, and divide the problem into always and initial
* threads.
*/
void synth_f::process(class Design*des, class NetProcTop*top)
{
switch (top->type()) {
case NetProcTop::KALWAYS:
top_ = top;
proc_always_(des);
break;
}
}
/*
* An "always ..." statement has been found.
*/
void synth_f::proc_always_(class Design*des)
{
match_dff dff_pat(des, top_);
if (top_->statement()->match_proc(&dff_pat)) {
dff_pat.make_it();
des->delete_process(top_);
return;
}
}
void synth(Design*des)
{
synth_f synth_obj;
des->functor(&synth_obj);
}
/*
* $Log: synth.cc,v $
* Revision 1.3 1999/12/01 06:06:16 steve
* Redo synth to use match_proc_t scanner.
*
* Revision 1.2 1999/11/02 04:55:34 steve
* Add the synthesize method to NetExpr to handle
* synthesis of expressions, and use that method
* to improve r-value handling of LPM_FF synthesis.
*
* Modify the XNF target to handle LPM_FF objects.
*
* Revision 1.1 1999/11/01 02:07:41 steve
* Add the synth functor to do generic synthesis
* and add the LPM_FF device to handle rows of
* flip-flops.
*
*/
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