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viaduct: Allow constraining only cascades without fanout

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2022-02-04 20:49:32 +00:00
parent 5ef5c33e9e
commit e5bfff6e9f
2 changed files with 5 additions and 2 deletions
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4
generic/viaduct_helpers.cc
View File

@ -82,7 +82,7 @@ void ViaductHelpers::remove_nextpnr_iobs(const pool<CellTypePort> &top_ports)
}
int ViaductHelpers::constrain_cell_pairs(const pool<CellTypePort> &src_ports, const pool<CellTypePort> &sink_ports,
int delta_z)
int delta_z, bool allow_fanout)
{
int constrained = 0;
for (auto &cell : ctx->cells) {
@ -96,6 +96,8 @@ int ViaductHelpers::constrain_cell_pairs(const pool<CellTypePort> &src_ports, co
continue;
if (!src_ports.count(CellTypePort(ci.type, port.first)))
continue;
if (!allow_fanout && port.second.net->users.size() > 1)
continue;
for (auto &usr : port.second.net->users) {
if (!sink_ports.count(CellTypePort(usr)))
continue;

3
generic/viaduct_helpers.h
View File

@ -70,7 +70,8 @@ struct ViaductHelpers
// expects a set of top-level port types
void remove_nextpnr_iobs(const pool<CellTypePort> &top_ports);
// Constrain cells with certain port connection patterns together with a fixed z-offset
int constrain_cell_pairs(const pool<CellTypePort> &src_ports, const pool<CellTypePort> &sink_ports, int delta_z);
int constrain_cell_pairs(const pool<CellTypePort> &src_ports, const pool<CellTypePort> &sink_ports, int delta_z,
bool allow_fanout = true);
// Replace constants with given driving cells
void replace_constants(CellTypePort vcc_driver, CellTypePort gnd_driver,
const dict<IdString, Property> &vcc_params = {},