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Temporary fix for br993 - assertion failure in flip-flop synthesis. 

Synthesis does not currently support some commonly used styles for
representing flip-flops, e.g.

  q <= 0;
  if (en) q <= 1;

or

  if (clr) q <= 0;
  if (set) q <= 1;

For now, output a "sorry" message.
This commit is contained in:
Martin Whitaker 2016-01-30 22:38:08 +00:00
parent a006dee990
commit 83a82914e0
1 changed files with 10 additions and 0 deletions
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10
synth2.cc
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@ -1421,6 +1421,16 @@ bool NetBlock::synth_sync(Design*des, NetScope*scope,
are used to collect the outputs from the substatement
for the inputs of the FF bank. */
NetBus tmp_out (scope, tmp_set.size());
for (unsigned idx = 0 ; idx < tmp_out.pin_count() ; idx += 1) {
unsigned ptr = nex_map.find_nexus(tmp_set[idx]);
ivl_assert(*this, ptr < nex_out.pin_count());
if (nex_out.pin(ptr).is_linked()) {
cerr << get_fileline() << ": sorry: multiple statements "
"assigning to the same flip-flop are not yet "
"supported in synthesis." << endl;
return false;
}
}
/* Create a temporary ff_ce (FF clock-enable) that
accounts for the subset of outputs that this