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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() 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
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