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Handle padding of MUX net results.

This commit is contained in:
steve 2006-04-28 05:09:51 +00:00
parent a2c036d5ab
commit 47b72c3b74
1 changed files with 18 additions and 4 deletions
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22
elab_net.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: elab_net.cc,v 1.181 2006/04/28 04:28:35 steve Exp $"
#ident "$Id: elab_net.cc,v 1.182 2006/04/28 05:09:51 steve Exp $"
#endif
# include "config.h"
@ -2494,7 +2494,10 @@ NetNet* PETernary::elaborate_net(Design*des, NetScope*scope,
/* This is the width of the LPM_MUX device that I'm about to
create. It may be smaller then the desired output, but I'll
handle padding below.
handle padding below. Note that in principle the
alternatives should be padded to the output width first,
but it is more efficient to pad them only just enough to
prevent loss, and do the finished padding later.
Create a NetNet object wide enough to hold the
result. Also, pad the result values (if necessary) so that
@ -2503,7 +2506,7 @@ NetNet* PETernary::elaborate_net(Design*des, NetScope*scope,
unsigned dwidth = (iwidth > width)? width : iwidth;
NetNet*sig = new NetNet(scope, scope->local_symbol(),
NetNet::WIRE, width);
NetNet::WIRE, dwidth);
sig->data_type(expr_type);
sig->local_flag(true);
@ -2554,10 +2557,18 @@ NetNet* PETernary::elaborate_net(Design*des, NetScope*scope,
/* If the MUX device result is too narrow to fill out the
desired result, pad with zeros... */
assert(dwidth == width);
assert(dwidth <= width);
des->add_node(mux);
/* If the MUX device results is too narrow to fill out the
desired result, then pad it. It is OK to have a too-narrow
result here because the dwidth choise is >= the width of
both alternatives. Thus, padding here is equivilent to
padding inside, and is cheaper. */
if (dwidth < width)
sig = pad_to_width(des, sig, width);
return sig;
}
@ -2750,6 +2761,9 @@ NetNet* PEUnary::elaborate_net(Design*des, NetScope*scope,
/*
* $Log: elab_net.cc,v $
* Revision 1.182 2006/04/28 05:09:51 steve
* Handle padding of MUX net results.
*
* Revision 1.181 2006/04/28 04:28:35 steve
* Allow concatenations as arguments to inout ports.
*