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Diffstat (limited to 'passes/sat/async2sync.cc')
| -rw-r--r-- | passes/sat/async2sync.cc | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/passes/sat/async2sync.cc b/passes/sat/async2sync.cc new file mode 100644 index 00000000..c92db711 --- /dev/null +++ b/passes/sat/async2sync.cc @@ -0,0 +1,147 @@ +/* + * yosys -- Yosys Open SYnthesis Suite + * + * Copyright (C) 2012 Clifford Wolf <clifford@clifford.at> + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + */ + +#include "kernel/yosys.h" +#include "kernel/sigtools.h" + +USING_YOSYS_NAMESPACE +PRIVATE_NAMESPACE_BEGIN + +struct Async2syncPass : public Pass { + Async2syncPass() : Pass("async2sync", "convert async FF inputs to sync circuits") { } + void help() YS_OVERRIDE + { + // |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---| + log("\n"); + log(" async2sync [options] [selection]\n"); + log("\n"); + log("This command replaces async FF inputs with sync circuits emulating the same\n"); + log("behavior for when the async signals are actually synchronized to the clock.\n"); + log("\n"); + log("This pass assumes negative hold time for the async FF inputs. For example when\n"); + log("a reset deasserts with the clock edge, then the FF output will still drive the\n"); + log("reset value in the next cycle regardless of the data-in value at the time of\n"); + log("the clock edge.\n"); + log("\n"); + log("Currently only $adff cells are supported by this pass.\n"); + log("\n"); + } + void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE + { + // bool flag_noinit = false; + + log_header(design, "Executing ASYNC2SYNC pass.\n"); + + size_t argidx; + for (argidx = 1; argidx < args.size(); argidx++) + { + // if (args[argidx] == "-noinit") { + // flag_noinit = true; + // continue; + // } + break; + } + extra_args(args, argidx, design); + + for (auto module : design->selected_modules()) + { + SigMap sigmap(module); + dict<SigBit, State> initbits; + pool<SigBit> del_initbits; + + for (auto wire : module->wires()) + if (wire->attributes.count("\\init") > 0) + { + Const initval = wire->attributes.at("\\init"); + SigSpec initsig = sigmap(wire); + + for (int i = 0; i < GetSize(initval) && i < GetSize(initsig); i++) + if (initval[i] == State::S0 || initval[i] == State::S1) + initbits[initsig[i]] = initval[i]; + } + + for (auto cell : vector<Cell*>(module->selected_cells())) + { + if (cell->type.in("$adff")) + { + // bool clk_pol = cell->parameters["\\CLK_POLARITY"].as_bool(); + bool arst_pol = cell->parameters["\\ARST_POLARITY"].as_bool(); + Const arst_val = cell->parameters["\\ARST_VALUE"]; + + SigSpec sig_clk = cell->getPort("\\CLK"); + SigSpec sig_arst = cell->getPort("\\ARST"); + SigSpec sig_d = cell->getPort("\\D"); + SigSpec sig_q = cell->getPort("\\Q"); + + log("Replacing %s.%s (%s): ARST=%s, D=%s, Q=%s\n", + log_id(module), log_id(cell), log_id(cell->type), + log_signal(sig_arst), log_signal(sig_d), log_signal(sig_q)); + + Const init_val; + for (int i = 0; i < GetSize(sig_q); i++) { + SigBit bit = sigmap(sig_q[i]); + init_val.bits.push_back(initbits.count(bit) ? initbits.at(bit) : State::Sx); + del_initbits.insert(bit); + } + + Wire *new_d = module->addWire(NEW_ID, GetSize(sig_d)); + Wire *new_q = module->addWire(NEW_ID, GetSize(sig_q)); + new_q->attributes["\\init"] = init_val; + + if (arst_pol) { + module->addMux(NEW_ID, sig_d, arst_val, sig_arst, new_d); + module->addMux(NEW_ID, new_q, arst_val, sig_arst, sig_q); + } else { + module->addMux(NEW_ID, arst_val, sig_d, sig_arst, new_d); + module->addMux(NEW_ID, arst_val, new_q, sig_arst, sig_q); + } + + cell->setPort("\\D", new_d); + cell->setPort("\\Q", new_q); + cell->unsetPort("\\ARST"); + cell->unsetParam("\\ARST_POLARITY"); + cell->unsetParam("\\ARST_VALUE"); + cell->type = "$dff"; + continue; + } + } + + for (auto wire : module->wires()) + if (wire->attributes.count("\\init") > 0) + { + bool delete_initattr = true; + Const initval = wire->attributes.at("\\init"); + SigSpec initsig = sigmap(wire); + + for (int i = 0; i < GetSize(initval) && i < GetSize(initsig); i++) + if (del_initbits.count(initsig[i]) > 0) + initval[i] = State::Sx; + else if (initval[i] != State::Sx) + delete_initattr = false; + + if (delete_initattr) + wire->attributes.erase("\\init"); + else + wire->attributes.at("\\init") = initval; + } + } + } +} Async2syncPass; + +PRIVATE_NAMESPACE_END |