Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

201 lines (163 sloc) 5.342 kb
/*
* Copyright (c) 1999-2011 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
*/
# include "config.h"
# include <iostream>
# include "PDelays.h"
# include "PExpr.h"
# include "verinum.h"
# include "netmisc.h"
bool dly_used_no_timescale = false;
bool dly_used_timescale = false;
bool display_ts_dly_warning = true;
PDelays::PDelays()
{
delete_flag_ = true;
for (unsigned idx = 0 ; idx < 3 ; idx += 1)
delay_[idx] = 0;
}
PDelays::~PDelays()
{
if (delete_flag_) {
for (unsigned idx = 0 ; idx < 3 ; idx += 1)
delete delay_[idx];
}
}
void PDelays::set_delay(PExpr*del)
{
assert(del);
assert(delay_[0] == 0);
delay_[0] = del;
delete_flag_ = true;
}
void PDelays::set_delays(const list<PExpr*>*del, bool df)
{
assert(del);
assert(del->size() <= 3);
list<PExpr*>::const_iterator cur = del->begin();
for (unsigned idx = 0 ; cur != del->end() ; idx += 1, ++cur)
delay_[idx] = *cur;
delete_flag_ = df;
}
unsigned PDelays::delay_count() const
{
unsigned dly_cnt = 0;
for (unsigned idx = 0 ; idx < 3 ; idx += 1)
if (delay_[idx]) dly_cnt += 1;
return dly_cnt;
}
static NetExpr*calculate_val(Design*des, NetScope*scope, PExpr*expr)
{
NetExpr*dex = elab_and_eval(des, scope, expr, -1);
/* Print a warning if we find default and `timescale based
* delays in the design, since this is likely an error. */
if (scope->time_from_timescale()) dly_used_timescale = true;
else dly_used_no_timescale = true;
if (display_ts_dly_warning &&
dly_used_no_timescale && dly_used_timescale) {
cerr << "warning: Found both default and "
"`timescale based delays. Use" << endl;
cerr << " -Wtimescale to find the "
"module(s) with no `timescale." << endl;
display_ts_dly_warning = false;
}
/* If the delay expression is a real constant or vector
constant, then evaluate it, scale it to the local time
units, and return an adjusted value. */
if (NetECReal*tmp = dynamic_cast<NetECReal*>(dex)) {
uint64_t delay = get_scaled_time_from_real(des, scope, tmp);
delete tmp;
NetEConst*tmp2 = new NetEConst(verinum(delay, 64));
tmp2->set_line(*expr);
return tmp2;
}
if (NetEConst*tmp = dynamic_cast<NetEConst*>(dex)) {
verinum fn = tmp->value();
uint64_t delay = des->scale_to_precision(fn.as_ulong64(), scope);
delete tmp;
NetEConst*tmp2 = new NetEConst(verinum(delay, 64));
tmp2->set_line(*expr);
return tmp2;
}
/* Oops, cannot evaluate down to a constant. */
return dex;
}
static NetExpr* make_delay_nets(Design*des, NetScope*scope, NetExpr*expr)
{
if (expr == 0)
return 0;
if (dynamic_cast<NetESignal*> (expr))
return expr;
if (dynamic_cast<NetEConst*> (expr))
return expr;
NetNet*sig = expr->synthesize(des, scope, expr);
if (sig == 0) {
cerr << expr->get_fileline() << ": error: Expression " << *expr
<< " is not suitable as a delay expression." << endl;
des->errors += 1;
return 0;
}
expr = new NetESignal(sig);
return expr;
}
static NetExpr* calc_decay_time(NetExpr *rise, NetExpr *fall)
{
NetEConst *c_rise = dynamic_cast<NetEConst*>(rise);
NetEConst *c_fall = dynamic_cast<NetEConst*>(fall);
if (c_rise && c_fall) {
if (c_rise->value() < c_fall->value()) return rise;
else return fall;
}
return 0;
}
void PDelays::eval_delays(Design*des, NetScope*scope,
NetExpr*&rise_time,
NetExpr*&fall_time,
NetExpr*&decay_time,
bool as_nets_flag) const
{
assert(scope);
if (delay_[0]) {
rise_time = calculate_val(des, scope, delay_[0]);
if (as_nets_flag)
rise_time = make_delay_nets(des, scope, rise_time);
if (delay_[1]) {
fall_time = calculate_val(des, scope, delay_[1]);
if (as_nets_flag)
fall_time = make_delay_nets(des, scope, fall_time);
if (delay_[2]) {
decay_time = calculate_val(des, scope, delay_[2]);
if (as_nets_flag)
decay_time = make_delay_nets(des, scope,
decay_time);
} else {
// If this is zero then we need to do the min()
// at run time.
decay_time = calc_decay_time(rise_time, fall_time);
}
} else {
assert(delay_[2] == 0);
fall_time = rise_time;
decay_time = rise_time;
}
} else {
rise_time = 0;
fall_time = 0;
decay_time = 0;
}
}
Jump to Line
Something went wrong with that request. Please try again.