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Detect constant shift distances in synthesis.

This commit is contained in:
steve 2003-04-08 05:07:15 +00:00
parent 2c129dfbfa
commit 58f2fe73c8
1 changed files with 54 additions and 6 deletions
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60
expr_synth.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: expr_synth.cc,v 1.42 2003/04/08 04:33:55 steve Exp $"
#ident "$Id: expr_synth.cc,v 1.43 2003/04/08 05:07:15 steve Exp $"
#endif
# include "config.h"
@ -400,19 +400,63 @@ NetNet* NetEBLogic::synthesize(Design*des)
NetNet* NetEBShift::synthesize(Design*des)
{
if (! dynamic_cast<NetEConst*>(right_)) {
NetExpr*tmp = right_->eval_tree();
if (tmp) {
delete right_;
right_ = tmp;
}
}
NetNet*lsig = left_->synthesize(des);
NetNet*rsig = right_->synthesize(des);
if (lsig == 0)
return 0;
if (rsig == 0)
return 0;
NetScope*scope = lsig->scope();
/* Detect the special case where the shift amount is
constant. Evaluate the shift amount, and simply reconnect
the left operand to the output, but shifted. */
if (NetEConst*rcon = dynamic_cast<NetEConst*>(right_)) {
verinum shift_v = rcon->value();
long shift = shift_v.as_long();
if (op() == 'r')
shift = 0-shift;
assert(shift >= 0);
if (shift == 0)
return lsig;
NetNet*osig = new NetNet(scope, scope->local_symbol(),
NetNet::IMPLICIT, expr_width());
osig->local_flag(true);
NetConst*zcon = new NetConst(scope, scope->local_symbol(),
verinum::V0);
des->add_node(zcon);
NetNet*zsig = new NetNet(scope, scope->local_symbol(),
NetNet::WIRE, 1);
connect(zcon->pin(0), zsig->pin(0));
for (unsigned idx = 0 ; idx < osig->pin_count() ; idx += 1) {
if (idx < shift) {
connect(osig->pin(idx), zsig->pin(0));
} else {
connect(osig->pin(idx), lsig->pin(idx-shift));
}
}
return osig;
}
NetNet*rsig = right_->synthesize(des);
if (rsig == 0)
return 0;
NetNet*osig = new NetNet(scope, scope->local_symbol(),
NetNet::IMPLICIT, expr_width());
osig->local_flag(true);
assert(op() == 'l');
NetCLShift*dev = new NetCLShift(scope, scope->local_symbol(),
@ -434,6 +478,7 @@ NetNet* NetEBShift::synthesize(Design*des)
NetNet*dir_n = new NetNet(scope, scope->local_symbol(),
NetNet::WIRE, 1);
NetConst*dir = new NetConst(scope, scope->local_symbol(), dir_v);
des->add_node(dir);
connect(dev->pin_Direction(), dir->pin(0));
connect(dev->pin_Direction(), dir_n->pin(0));
@ -683,6 +728,9 @@ NetNet* NetESignal::synthesize(Design*des)
/*
* $Log: expr_synth.cc,v $
* Revision 1.43 2003/04/08 05:07:15 steve
* Detect constant shift distances in synthesis.
*
* Revision 1.42 2003/04/08 04:33:55 steve
* Synthesize shift expressions.
*