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yosys/passes/sat/async2sync.cc

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/*
* 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"
#include "kernel/ffinit.h"
#include "kernel/ff.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct Async2syncPass : public Pass {
Async2syncPass() : Pass("async2sync", "convert async FF inputs to sync circuits") { }
void help() 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, $dffsr, and $dlatch cells are supported by this pass.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) 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);
FfInitVals initvals(&sigmap, module);
for (auto cell : vector<Cell*>(module->selected_cells()))
{
if (!RTLIL::builtin_ff_cell_types().count(cell->type))
continue;
FfData ff(&initvals, cell);
// Skip for $_FF_ and $ff cells.
if (ff.has_d && !ff.has_clk && !ff.has_en)
continue;
if (ff.has_clk)
{
if (!ff.has_sr && !ff.has_arst)
continue;
if (ff.has_sr) {
ff.unmap_ce_srst(module);
log("Replacing %s.%s (%s): SET=%s, CLR=%s, D=%s, Q=%s\n",
log_id(module), log_id(cell), log_id(cell->type),
log_signal(ff.sig_set), log_signal(ff.sig_clr), log_signal(ff.sig_d), log_signal(ff.sig_q));
initvals.remove_init(ff.sig_q);
Wire *new_d = module->addWire(NEW_ID, ff.width);
Wire *new_q = module->addWire(NEW_ID, ff.width);
SigSpec sig_set = ff.sig_set;
SigSpec sig_clr = ff.sig_clr;
if (!ff.pol_set) {
if (!ff.is_fine)
sig_set = module->Not(NEW_ID, sig_set);
else
sig_set = module->NotGate(NEW_ID, sig_set);
}
if (ff.pol_clr) {
if (!ff.is_fine)
sig_clr = module->Not(NEW_ID, sig_clr);
else
sig_clr = module->NotGate(NEW_ID, sig_clr);
}
if (!ff.is_fine) {
SigSpec tmp = module->Or(NEW_ID, ff.sig_d, sig_set);
module->addAnd(NEW_ID, tmp, sig_clr, new_d);
tmp = module->Or(NEW_ID, new_q, sig_set);
module->addAnd(NEW_ID, tmp, sig_clr, ff.sig_q);
} else {
SigSpec tmp = module->OrGate(NEW_ID, ff.sig_d, sig_set);
module->addAndGate(NEW_ID, tmp, sig_clr, new_d);
tmp = module->OrGate(NEW_ID, new_q, sig_set);
module->addAndGate(NEW_ID, tmp, sig_clr, ff.sig_q);
}
ff.sig_d = new_d;
ff.sig_q = new_q;
ff.has_sr = false;
} else if (ff.has_arst) {
ff.unmap_srst(module);
log("Replacing %s.%s (%s): ARST=%s, D=%s, Q=%s\n",
log_id(module), log_id(cell), log_id(cell->type),
log_signal(ff.sig_arst), log_signal(ff.sig_d), log_signal(ff.sig_q));
initvals.remove_init(ff.sig_q);
Wire *new_q = module->addWire(NEW_ID, ff.width);
if (ff.pol_arst) {
if (!ff.is_fine)
module->addMux(NEW_ID, new_q, ff.val_arst, ff.sig_arst, ff.sig_q);
else
module->addMuxGate(NEW_ID, new_q, ff.val_arst[0], ff.sig_arst, ff.sig_q);
} else {
if (!ff.is_fine)
module->addMux(NEW_ID, ff.val_arst, new_q, ff.sig_arst, ff.sig_q);
else
module->addMuxGate(NEW_ID, ff.val_arst[0], new_q, ff.sig_arst, ff.sig_q);
}
ff.sig_q = new_q;
ff.has_arst = false;
ff.has_srst = true;
ff.val_srst = ff.val_arst;
ff.sig_srst = ff.sig_arst;
ff.pol_srst = ff.pol_arst;
}
}
else
{
// Latch.
log("Replacing %s.%s (%s): EN=%s, D=%s, Q=%s\n",
log_id(module), log_id(cell), log_id(cell->type),
log_signal(ff.sig_en), log_signal(ff.sig_d), log_signal(ff.sig_q));
initvals.remove_init(ff.sig_q);
Wire *new_q = module->addWire(NEW_ID, ff.width);
Wire *new_d;
if (ff.has_d) {
new_d = module->addWire(NEW_ID, ff.width);
if (ff.pol_en) {
if (!ff.is_fine)
module->addMux(NEW_ID, new_q, ff.sig_d, ff.sig_en, new_d);
else
module->addMuxGate(NEW_ID, new_q, ff.sig_d, ff.sig_en, new_d);
} else {
if (!ff.is_fine)
module->addMux(NEW_ID, ff.sig_d, new_q, ff.sig_en, new_d);
else
module->addMuxGate(NEW_ID, ff.sig_d, new_q, ff.sig_en, new_d);
}
} else {
new_d = new_q;
}
if (ff.has_sr) {
SigSpec sig_set = ff.sig_set;
SigSpec sig_clr = ff.sig_clr;
if (!ff.pol_set) {
if (!ff.is_fine)
sig_set = module->Not(NEW_ID, sig_set);
else
sig_set = module->NotGate(NEW_ID, sig_set);
}
if (ff.pol_clr) {
if (!ff.is_fine)
sig_clr = module->Not(NEW_ID, sig_clr);
else
sig_clr = module->NotGate(NEW_ID, sig_clr);
}
if (!ff.is_fine) {
SigSpec tmp = module->Or(NEW_ID, new_d, sig_set);
module->addAnd(NEW_ID, tmp, sig_clr, ff.sig_q);
} else {
SigSpec tmp = module->OrGate(NEW_ID, new_d, sig_set);
module->addAndGate(NEW_ID, tmp, sig_clr, ff.sig_q);
}
} else if (ff.has_arst) {
if (ff.pol_arst) {
if (!ff.is_fine)
module->addMux(NEW_ID, new_d, ff.val_arst, ff.sig_arst, ff.sig_q);
else
module->addMuxGate(NEW_ID, new_d, ff.val_arst[0], ff.sig_arst, ff.sig_q);
} else {
if (!ff.is_fine)
module->addMux(NEW_ID, ff.val_arst, new_d, ff.sig_arst, ff.sig_q);
else
module->addMuxGate(NEW_ID, ff.val_arst[0], new_d, ff.sig_arst, ff.sig_q);
}
} else {
module->connect(ff.sig_q, new_d);
}
ff.sig_d = new_d;
ff.sig_q = new_q;
ff.has_en = false;
ff.has_arst = false;
ff.has_sr = false;
ff.has_d = true;
}
IdString name = cell->name;
module->remove(cell);
ff.emit(module, name);
}
}
}
} Async2syncPass;
PRIVATE_NAMESPACE_END
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