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Handle simple memory addressing in expression synthesis.

This commit is contained in:
steve 2006-06-15 01:57:26 +00:00
parent 3877b636df
commit 101810df21
1 changed files with 22 additions and 4 deletions
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26
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 1.59.2.7 2006/06/14 03:02:54 steve Exp $"
#ident "$Id: expr_synth.cc,v 1.59.2.8 2006/06/15 01:57:26 steve Exp $"
#endif
# include "config.h"
@ -693,7 +693,7 @@ NetNet* NetEMemory::synthesize(Design*des)
{
NetScope*scope = mem_->scope();
NetNet*explode = mem_->reg_from_explode();
NetNet*explode = mem_->explode_to_reg();
unsigned width = expr_width();
assert(idx_);
@ -708,11 +708,26 @@ NetNet* NetEMemory::synthesize(Design*des)
if (debug_synth)
cerr << get_line() << ": debug: synthesize read of "
<< explode->pin_count() << " bit exploded memory." << endl;
/* Only make a muc big enough to address the words that
the address can generate. (If the address is
0-extended, then only the low words are addressable.) */
unsigned use_count = mem_->count();
if (use_count > (1U << addr->pin_count())) {
use_count = 1 << addr->pin_count();
if (debug_synth)
cerr << get_line() << ": debug: "
<< "Index expression can only address "
<< use_count << " of "
<< mem_->count() << " words." << endl;
}
/* This is a reference to an exploded memory. So locate
the reg vector and use the addr expression as a
select into a MUX. */
NetMux*mux = new NetMux(scope, scope->local_symbol(),
width, mem_->count(), addr->pin_count());
width, use_count, addr->pin_count());
des->add_node(mux);
mux->set_line(*this);
@ -721,7 +736,7 @@ NetNet* NetEMemory::synthesize(Design*des)
for (unsigned idx = 0 ; idx < mux->sel_width() ; idx += 1)
connect(mux->pin_Sel(idx), addr->pin(idx));
for (unsigned wrd = 0 ; wrd < mem_->count() ; wrd += 1)
for (unsigned wrd = 0 ; wrd < use_count ; wrd += 1)
for (unsigned idx = 0 ; idx < width ; idx += 1) {
unsigned bit = wrd*width + idx;
connect(mux->pin_Data(idx, wrd), explode->pin(bit));
@ -988,6 +1003,9 @@ NetNet* NetESignal::synthesize(Design*des)
/*
* $Log: expr_synth.cc,v $
* Revision 1.59.2.8 2006/06/15 01:57:26 steve
* Handle simple memory addressing in expression synthesis.
*
* Revision 1.59.2.7 2006/06/14 03:02:54 steve
* synthesis for NetEBitSel.
*