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When making NetCondit objects, handle output part select. 

When a mux (NetCondit) is only writing to a part of the output
vector (and using only a part of the inputs) then blend the mux
output with the previous statement output.
This commit is contained in:
Stephen Williams 2014-05-25 18:33:26 -07:00
parent 76883fa18c
commit ef79f538d5
2 changed files with 30 additions and 0 deletions
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4
netmisc.cc
View File

@ -1382,6 +1382,10 @@ NetPartSelect* detect_partselect_lval(Link&pin)
unsigned obj_pin;
cur->cur_link(obj, obj_pin);
// Skip NexusSet objects.
if (obj == 0)
continue;
// NetNet pins have no effect on this search.
if (dynamic_cast<NetNet*> (obj))
continue;

26
synth2.cc
View File

@ -440,6 +440,8 @@ bool NetCondit::synth_async(Design*des, NetScope*scope,
<< endl;
}
NetBus statement_input (scope, nex_out.pin_count());
bool flag;
NetBus asig(scope, nex_out.pin_count());
NetBus atmp(scope, nex_out.pin_count());
@ -459,6 +461,9 @@ bool NetCondit::synth_async(Design*des, NetScope*scope,
} else {
for (unsigned idx = 0 ; idx < nex_out.pin_count() ; idx += 1) {
connect(statement_input.pin(idx), accumulated_nex_out.pin(idx));
}
if (debug_synth2) {
cerr << get_fileline() << ": NetCondit::synth_async: "
<< "Synthesize else clause at " << else_->get_fileline()
@ -598,6 +603,27 @@ bool NetCondit::synth_async(Design*des, NetScope*scope,
connect(nex_out.pin(idx), otmp->pin(0));
// Handle the special case that this NetMux is only
// assigning to a part of the vector. If that is the
// case, then we need to blend this output with the
// already calculated input to this statement so that we
// don't accidentally disconnect the other drivers to
// other bits.
// FIXME: NEED TO CHECK THAT THESE DRIVERS DON'T
// OVERLAP. THIS CODE CURRENTLY DOESN'T DO THAT TEST.
if (mux_width < mux_lwidth && if_ && else_) {
if (debug_synth2) {
cerr << get_fileline() << ": NetCondit::synth_async: "
<< "This MetMux only impacts a few bits of output,"
<< " so combine nex_out with statement input."
<< endl;
cerr << get_fileline() << ": NetCondit::synth_async: "
<< "MISSING TEST FOR CORRECTNESS OF THE BLEND!"
<< endl;
}
connect(nex_out.pin(idx), statement_input.pin(idx));
}
des->add_node(mux);
}