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Diffstat (limited to 'passes/techmap/dff2dffs.cc')
| -rw-r--r-- | passes/techmap/dff2dffs.cc | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/passes/techmap/dff2dffs.cc b/passes/techmap/dff2dffs.cc new file mode 100644 index 00000000..39a4f6ad --- /dev/null +++ b/passes/techmap/dff2dffs.cc @@ -0,0 +1,142 @@ +/* + * yosys -- Yosys Open SYnthesis Suite + * + * Copyright (C) 2012 Clifford Wolf <clifford@clifford.at> + * Copyright (C) 2018 David Shah <dave@ds0.me> + * + * 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 Dff2dffsPass : public Pass { + Dff2dffsPass() : Pass("dff2dffs", "process sync set/reset with SR over CE priority") { } + void help() YS_OVERRIDE + { + log("\n"); + log(" dff2dffs [options] [selection]\n"); + log("\n"); + log("Merge synchronous set/reset $_MUX_ cells to create $__DFFS_[NP][NP][01], to be run before\n"); + log("dff2dffe for SR over CE priority.\n"); + log("\n"); + } + void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE + { + log_header(design, "Executing dff2dffs pass (merge synchronous set/reset into FF cells).\n"); + + size_t argidx; + for (argidx = 1; argidx < args.size(); argidx++) + { + // if (args[argidx] == "-singleton") { + // singleton_mode = true; + // continue; + // } + break; + } + extra_args(args, argidx, design); + + pool<IdString> dff_types; + dff_types.insert("$_DFF_N_"); + dff_types.insert("$_DFF_P_"); + + for (auto module : design->selected_modules()) + { + log("Merging set/reset $_MUX_ cells into DFFs in %s.\n", log_id(module)); + + SigMap sigmap(module); + dict<SigBit, Cell*> sr_muxes; + vector<Cell*> ff_cells; + + for (auto cell : module->selected_cells()) + { + if (dff_types.count(cell->type)) { + ff_cells.push_back(cell); + continue; + } + + if (cell->type != "$_MUX_") + continue; + + SigBit bit_a = sigmap(cell->getPort("\\A")); + SigBit bit_b = sigmap(cell->getPort("\\B")); + + if (bit_a.wire == nullptr || bit_b.wire == nullptr) + sr_muxes[sigmap(cell->getPort("\\Y"))] = cell; + } + + for (auto cell : ff_cells) + { + SigSpec sig_d = cell->getPort("\\D"); + + if (GetSize(sig_d) < 1) + continue; + + SigBit bit_d = sigmap(sig_d[0]); + + if (sr_muxes.count(bit_d) == 0) + continue; + + Cell *mux_cell = sr_muxes.at(bit_d); + SigBit bit_a = sigmap(mux_cell->getPort("\\A")); + SigBit bit_b = sigmap(mux_cell->getPort("\\B")); + SigBit bit_s = sigmap(mux_cell->getPort("\\S")); + + log(" Merging %s (A=%s, B=%s, S=%s) into %s (%s).\n", log_id(mux_cell), + log_signal(bit_a), log_signal(bit_b), log_signal(bit_s), log_id(cell), log_id(cell->type)); + + SigBit sr_val, sr_sig; + bool invert_sr; + sr_sig = bit_s; + if (bit_a.wire == nullptr) { + bit_d = bit_b; + sr_val = bit_a; + invert_sr = true; + } else { + log_assert(bit_b.wire == nullptr); + bit_d = bit_a; + sr_val = bit_b; + invert_sr = false; + } + + if (sr_val == State::S1) { + if (cell->type == "$_DFF_N_") { + if (invert_sr) cell->type = "$__DFFS_NN1_"; + else cell->type = "$__DFFS_NP1_"; + } else { + log_assert(cell->type == "$_DFF_P_"); + if (invert_sr) cell->type = "$__DFFS_PN1_"; + else cell->type = "$__DFFS_PP1_"; + } + } else { + if (cell->type == "$_DFF_N_") { + if (invert_sr) cell->type = "$__DFFS_NN0_"; + else cell->type = "$__DFFS_NP0_"; + } else { + log_assert(cell->type == "$_DFF_P_"); + if (invert_sr) cell->type = "$__DFFS_PN0_"; + else cell->type = "$__DFFS_PP0_"; + } + } + cell->setPort("\\R", sr_sig); + cell->setPort("\\D", bit_d); + } + } + } +} Dff2dffsPass; + +PRIVATE_NAMESPACE_END |