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Detect asynchronous FF inputs that are expressions.

This commit is contained in:
steve 2003-08-10 17:04:23 +00:00
parent b6c3f94d52
commit fff8278eb4
1 changed files with 63 additions and 41 deletions
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52
synth2.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CVS_IDENT
#ident "$Id: synth2.cc,v 1.27 2003/06/23 00:14:44 steve Exp $"
#ident "$Id: synth2.cc,v 1.28 2003/08/10 17:04:23 steve Exp $"
#endif
# include "config.h"
@ -481,28 +481,41 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
const NetNet*nex_map, NetNet*nex_out,
const svector<NetEvProbe*>&events_in)
{
/* First try to turn the condition expression into an
asynchronous set/reset. If the condition expression has
inputs that are included in the sensitivity list, then it
is likely intended as an asynchronous input. */
/* Synthesize the enable expression. */
NetNet*ce = expr_->synthesize(des);
assert(ce->pin_count() == 1);
/* Try first to turn the ce into an asynchronous set/reset
input. If the ce is linked to a probe, then that probe is a
set/reset input. */
NexusSet*expr_input = expr_->nex_input();
assert(expr_input);
for (unsigned idx = 0 ; idx < events_in.count() ; idx += 1) {
NetEvProbe*ev = events_in[idx];
NexusSet pin_set;
pin_set.add(ev->pin(0).nexus());
if (connected(ce->pin(0), ev->pin(0))) {
if (! expr_input->contains(pin_set))
continue;
bool flag = true;
assert(ev->edge() == NetEvProbe::POSEDGE);
/* Ah, this edge is in the sensitivity list for the
expression, so we have an asynchronous
input. Synthesize the set/reset input expression. */
NetNet*rst = expr_->synthesize(des);
assert(rst->pin_count() == 1);
/* XXXX I really should find a way to check that the
edge used on the reset input is correct. This would
involve interpreting the exression that is fed by the
reset expression. */
//assert(ev->edge() == NetEvProbe::POSEDGE);
/* Synthesize the true clause to figure out what
kind of set/reset we have. */
NetNet*asig = new NetNet(scope, scope->local_symbol(),
NetNet::WIRE, nex_map->pin_count());
asig->local_flag(true);
flag = if_->synth_async(des, scope, nex_map, asig) && flag;
bool flag = if_->synth_async(des, scope, nex_map, asig);
assert(asig->pin_count() == ff->width());
@ -519,14 +532,15 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
assert(tmp.is_defined());
if (tmp.is_zero()) {
connect(ff->pin_Aclr(), ce->pin(0));
connect(ff->pin_Aclr(), rst->pin(0));
} else {
connect(ff->pin_Aset(), ce->pin(0));
connect(ff->pin_Aset(), rst->pin(0));
ff->aset_value(tmp);
}
delete asig;
delete expr_input;
assert(events_in.count() == 1);
return else_->synth_sync(des, scope, ff, nex_map,
@ -534,7 +548,7 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
&& flag;
}
}
delete expr_input;
/* Failed to find an asynchronous set/reset, so any events
input are probably in error. */
@ -544,6 +558,11 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
des->errors += 1;
}
/* Synthesize the enable expression. */
NetNet*ce = expr_->synthesize(des);
assert(ce->pin_count() == 1);
/* If this is an if/then/else, then it is likely a
combinational if, and I should synthesize it that way. */
if (if_ && else_) {
@ -784,6 +803,9 @@ void synth2(Design*des)
/*
* $Log: synth2.cc,v $
* Revision 1.28 2003/08/10 17:04:23 steve
* Detect asynchronous FF inputs that are expressions.
*
* Revision 1.27 2003/06/23 00:14:44 steve
* ivl_synthesis_cell cuts off synthesis within a module.
*