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Handle nested-if chip enables.

This commit is contained in:
steve 2002-11-09 23:29:29 +00:00
parent 3178f886b7
commit 1742231eba
1 changed files with 48 additions and 9 deletions
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55
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 1.19 2002/11/09 20:22:57 steve Exp $"
#ident "$Id: synth2.cc,v 1.20 2002/11/09 23:29:29 steve Exp $"
#endif
# include "config.h"
@ -440,6 +440,7 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
const NetNet*nex_map, NetNet*nex_out,
const svector<NetEvProbe*>&events_in)
{
/* Synthesize the enable expression. */
NetNet*ce = expr_->synthesize(des);
assert(ce->pin_count() == 1);
@ -452,6 +453,7 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
if (connected(ce->pin(0), ev->pin(0))) {
bool flag = true;
assert(ev->edge() == NetEvProbe::POSEDGE);
/* Synthesize the true clause to figure out what
@ -459,7 +461,7 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
NetNet*asig = new NetNet(scope, scope->local_hsymbol(),
NetNet::WIRE, nex_map->pin_count());
asig->local_flag(true);
if_->synth_async(des, scope, nex_map, asig);
flag = if_->synth_async(des, scope, nex_map, asig) && flag;
assert(asig->pin_count() == ff->width());
@ -487,7 +489,8 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
assert(events_in.count() == 1);
return else_->synth_sync(des, scope, ff, nex_map,
nex_out, svector<NetEvProbe*>(0));
nex_out, svector<NetEvProbe*>(0))
&& flag;
}
}
@ -509,14 +512,47 @@ bool NetCondit::synth_sync(Design*des, NetScope*scope, NetFF*ff,
assert(if_);
assert(!else_);
/* Synthesize the input to the DFF. */
bool flag = if_->synth_async(des, scope, nex_map, nex_out);
if (flag == false)
return flag;
/* What's left, is a synchronous CE statement like this:
assert(expr_);
if (expr_) <true statement>;
The expr_ expression has alreacy been synthesized to the ce
net, so we connect it here to the FF. What's left is to
synthesize the substatement as a combinational
statement.
Watch out for the special case that there is already a CE
connected to this FF. This can be caused by code like this:
if (a) if (b) <statement>;
In this case, we are working on the inner IF, so we AND the
a and b expressions to make a new CE. */
if (ff->pin_Enable().is_linked()) {
NetLogic*ce_and = new NetLogic(scope,
scope->local_hsymbol(), 3,
NetLogic::AND);
des->add_node(ce_and);
connect(ff->pin_Enable(), ce_and->pin(1));
connect(ce->pin(0), ce_and->pin(2));
ff->pin_Enable().unlink();
connect(ff->pin_Enable(), ce_and->pin(0));
NetNet*tmp = new NetNet(scope, scope->local_hsymbol(),
NetNet::IMPLICIT, 1);
tmp->local_flag(true);
connect(ff->pin_Enable(), tmp->pin(0));
} else {
connect(ff->pin_Enable(), ce->pin(0));
}
bool flag = if_->synth_sync(des, scope, ff, nex_map, nex_out, events_in);
if (flag == false)
return flag;
return true;
}
@ -702,6 +738,9 @@ void synth2(Design*des)
/*
* $Log: synth2.cc,v $
* Revision 1.20 2002/11/09 23:29:29 steve
* Handle nested-if chip enables.
*
* Revision 1.19 2002/11/09 20:22:57 steve
* Detect synthesis conflicts blocks statements share outputs.
*