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nexus: Fix FASM gen for DCC-thru

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2021-06-16 13:23:42 +01:00
parent ded32f3390
commit 84fc2877c6
1 changed files with 34 additions and 3 deletions
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37
nexus/fasm.cc
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@ -227,9 +227,8 @@ struct NexusFasmWriter
blank();
}
// Find the CIBMUX output for a signal
WireId find_cibmux(const CellInfo *cell, IdString pin)
WireId find_cibmux(WireId cursor)
{
WireId cursor = ctx->getBelPinWire(cell->bel, pin);
if (cursor == WireId())
return WireId();
for (int i = 0; i < 10; i++) {
@ -270,7 +269,7 @@ struct NexusFasmWriter
// Handle CIB muxes - these must be set such that floating pins really are floating to VCC and not connected
// to another CIB signal
if ((pin_style & PINBIT_CIBMUX) && port.second.net == nullptr) {
WireId cibmuxout = find_cibmux(cell, port.first);
WireId cibmuxout = find_cibmux(ctx->getBelPinWire(cell->bel, port.first));
if (cibmuxout != WireId()) {
write_comment(stringf("CIBMUX for unused pin %s", ctx->nameOf(port.first)));
bool found = false;
@ -287,6 +286,36 @@ struct NexusFasmWriter
}
}
// Handle route-through DCCs
void write_dcc_thru()
{
for (auto bel : ctx->getBels()) {
if (ctx->getBelType(bel) != id_DCC)
continue;
if (!ctx->checkBelAvail(bel))
continue;
WireId dst = ctx->getBelPinWire(bel, id_CLKO);
if (ctx->getBoundWireNet(dst) == nullptr)
continue;
// Set up the CIBMUX so CE is guaranteed to be tied high
WireId ce = ctx->getBelPinWire(bel, id_CE);
WireId cibmuxout = find_cibmux(ce);
NPNR_ASSERT(cibmuxout != WireId());
write_comment(stringf("CE CIBMUX for DCC route-thru %s", ctx->nameOfBel(bel)));
bool found = false;
for (PipId pip : ctx->getPipsUphill(cibmuxout)) {
if (ctx->checkPipAvail(pip) && ctx->checkWireAvail(ctx->getPipSrcWire(pip))) {
write_pip(pip);
found = true;
break;
}
}
NPNR_ASSERT(found);
}
}
// Write config for an OXIDE_COMB cell
void write_comb(const CellInfo *cell)
{
@ -846,6 +875,8 @@ struct NexusFasmWriter
write_dphy(ci);
blank();
}
// Handle DCC route-throughs
write_dcc_thru();
// Write config for unused bels
write_unused();
// Write bank config