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/*
* 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() override
{
log("\n");
log(" dff2dffs [options] [selection]\n");
log("\n");
log("Merge synchronous set/reset $_MUX_ cells to create $_SDFF_[NP][NP][01]_, to be run before\n");
log("dff2dffe for SR over CE priority.\n");
log("\n");
log(" -match-init\n");
log(" Disallow merging synchronous set/reset that has polarity opposite of the\n");
log(" output wire's init attribute (if any).\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
log_header(design, "Executing dff2dffs pass (merge synchronous set/reset into FF cells).\n");
bool match_init = false;
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++)
{
// if (args[argidx] == "-singleton") {
// singleton_mode = true;
// continue;
// }
if (args[argidx] == "-match-init") {
match_init = true;
continue;
}
break;
}
extra_args(args, argidx, design);
pool<IdString> dff_types;
dff_types.insert(ID($_DFF_N_));
dff_types.insert(ID($_DFF_P_));
for (auto module : design->selected_modules())
{
log("Merging set/reset $_MUX_ cells into DFFs in %s.\n", log_id(module));
SigMap sigmap(module);
dict<SigBit, Cell*> sr_muxes;
vector<Cell*> ff_cells;
for (auto cell : module->selected_cells())
{
if (dff_types.count(cell->type)) {
ff_cells.push_back(cell);
continue;
}
if (cell->type != ID($_MUX_))
continue;
SigBit bit_a = sigmap(cell->getPort(ID::A));
SigBit bit_b = sigmap(cell->getPort(ID::B));
if (bit_a.wire == nullptr || bit_b.wire == nullptr)
sr_muxes[sigmap(cell->getPort(ID::Y))] = cell;
}
for (auto cell : ff_cells)
{
SigSpec sig_d = cell->getPort(ID::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(ID::A));
SigBit bit_b = sigmap(mux_cell->getPort(ID::B));
SigBit bit_s = sigmap(mux_cell->getPort(ID::S));
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 (match_init) {
SigBit bit_q = cell->getPort(ID::Q);
if (bit_q.wire) {
auto it = bit_q.wire->attributes.find(ID::init);
if (it != bit_q.wire->attributes.end()) {
auto init_val = it->second[bit_q.offset];
if (init_val == State::S1 && sr_val != State::S1)
continue;
if (init_val == State::S0 && sr_val != State::S0)
continue;
}
}
}
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));
if (sr_val == State::S1) {
if (cell->type == ID($_DFF_N_)) {
if (invert_sr) cell->type = ID($_SDFF_NN1_);
else cell->type = ID($_SDFF_NP1_);
} else {
log_assert(cell->type == ID($_DFF_P_));
if (invert_sr) cell->type = ID($_SDFF_PN1_);
else cell->type = ID($_SDFF_PP1_);
}
} else {
if (cell->type == ID($_DFF_N_)) {
if (invert_sr) cell->type = ID($_SDFF_NN0_);
else cell->type = ID($_SDFF_NP0_);
} else {
log_assert(cell->type == ID($_DFF_P_));
if (invert_sr) cell->type = ID($_SDFF_PN0_);
else cell->type = ID($_SDFF_PP0_);
}
}
cell->setPort(ID::R, sr_sig);
cell->setPort(ID::D, bit_d);
}
}
}
} Dff2dffsPass;
PRIVATE_NAMESPACE_END
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