diff options
Diffstat (limited to 'mistral/pack.cc')
| -rw-r--r-- | mistral/pack.cc | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/mistral/pack.cc b/mistral/pack.cc index 78657321..aed9572e 100644 --- a/mistral/pack.cc +++ b/mistral/pack.cc @@ -275,11 +275,52 @@ struct MistralPacker } } + void constrain_carries() + { + for (auto cell : sorted(ctx->cells)) { + CellInfo *ci = cell.second; + if (ci->type != id_MISTRAL_ALUT_ARITH) + continue; + const NetInfo *cin = get_net_or_empty(ci, id_CI); + if (cin != nullptr && cin->driver.cell != nullptr) + continue; // not the start of a chain + std::vector<CellInfo *> chain; + CellInfo *cursor = ci; + while (true) { + chain.push_back(cursor); + const NetInfo *co = get_net_or_empty(cursor, id_CO); + if (co == nullptr || co->users.empty()) + break; + if (co->users.size() > 1) + log_error("Carry net %s has more than one sink!\n", ctx->nameOf(co)); + auto &usr = co->users.at(0); + if (usr.port != id_CI) + log_error("Carry net %s drives port %s, expected CI\n", ctx->nameOf(co), ctx->nameOf(usr.port)); + cursor = usr.cell; + } + + chain.at(0)->constr_abs_z = true; + chain.at(0)->constr_z = 0; + chain.at(0)->cluster = chain.at(0)->name; + + for (int i = 1; i < int(chain.size()); i++) { + chain.at(i)->constr_x = 0; + chain.at(i)->constr_y = (i / 20); + // 2 COMB, 4 FF per ALM + chain.at(i)->constr_z = ((i / 2) % 10) * 6 + (i % 2); + chain.at(i)->constr_abs_z = true; + chain.at(i)->cluster = chain.at(0)->name; + chain.at(0)->constr_children.push_back(chain.at(i)); + } + } + } + void run() { init_constant_nets(); pack_constants(); pack_io(); + constrain_carries(); } }; }; // namespace |