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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"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct TribufConfig {
bool merge_mode;
bool logic_mode;
TribufConfig() {
merge_mode = false;
logic_mode = false;
}
};
struct TribufWorker {
Module *module;
SigMap sigmap;
const TribufConfig &config;
TribufWorker(Module *module, const TribufConfig &config) : module(module), sigmap(module), config(config)
{
}
static bool is_all_z(SigSpec sig)
{
for (auto bit : sig)
if (bit != State::Sz)
return false;
return true;
}
void run()
{
dict<SigSpec, vector<Cell*>> tribuf_cells;
pool<SigBit> output_bits;
if (config.logic_mode)
for (auto wire : module->wires())
if (wire->port_output)
for (auto bit : sigmap(wire))
output_bits.insert(bit);
for (auto cell : module->selected_cells())
{
if (cell->type == "$tribuf")
tribuf_cells[sigmap(cell->getPort("\\Y"))].push_back(cell);
if (cell->type == "$_TBUF_")
tribuf_cells[sigmap(cell->getPort("\\Y"))].push_back(cell);
if (cell->type.in("$mux", "$_MUX_"))
{
IdString en_port = cell->type == "$mux" ? "\\EN" : "\\E";
IdString tri_type = cell->type == "$mux" ? "$tribuf" : "$_TBUF_";
if (is_all_z(cell->getPort("\\A")) && is_all_z(cell->getPort("\\B"))) {
module->remove(cell);
continue;
}
if (is_all_z(cell->getPort("\\A"))) {
cell->setPort("\\A", cell->getPort("\\B"));
cell->setPort(en_port, cell->getPort("\\S"));
cell->unsetPort("\\B");
cell->unsetPort("\\S");
cell->type = tri_type;
tribuf_cells[sigmap(cell->getPort("\\Y"))].push_back(cell);
continue;
}
if (is_all_z(cell->getPort("\\B"))) {
cell->setPort(en_port, module->Not(NEW_ID, cell->getPort("\\S")));
cell->unsetPort("\\B");
cell->unsetPort("\\S");
cell->type = tri_type;
tribuf_cells[sigmap(cell->getPort("\\Y"))].push_back(cell);
continue;
}
}
}
if (config.merge_mode || config.logic_mode)
{
for (auto &it : tribuf_cells)
{
bool no_tribuf = false;
if (config.logic_mode) {
no_tribuf = true;
for (auto bit : it.first)
if (output_bits.count(bit))
no_tribuf = false;
}
if (GetSize(it.second) <= 1 && !no_tribuf)
continue;
SigSpec pmux_b, pmux_s;
for (auto cell : it.second) {
if (cell->type == "$tribuf")
pmux_s.append(cell->getPort("\\EN"));
else
pmux_s.append(cell->getPort("\\E"));
pmux_b.append(cell->getPort("\\A"));
module->remove(cell);
}
SigSpec muxout = GetSize(pmux_s) > 1 ? module->Pmux(NEW_ID, SigSpec(State::Sx, GetSize(it.first)), pmux_b, pmux_s) : pmux_b;
if (no_tribuf)
module->connect(it.first, muxout);
else
module->addTribuf(NEW_ID, muxout, module->ReduceOr(NEW_ID, pmux_s), it.first);
}
}
}
};
struct TribufPass : public Pass {
TribufPass() : Pass("tribuf", "infer tri-state buffers") { }
void help() YS_OVERRIDE
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" tribuf [options] [selection]\n");
log("\n");
log("This pass transforms $mux cells with 'z' inputs to tristate buffers.\n");
log("\n");
log(" -merge\n");
log(" merge multiple tri-state buffers driving the same net\n");
log(" into a single buffer.\n");
log("\n");
log(" -logic\n");
log(" convert tri-state buffers that do not drive output ports\n");
log(" to non-tristate logic. this option implies -merge.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
{
TribufConfig config;
log_header(design, "Executing TRIBUF pass.\n");
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-merge") {
config.merge_mode = true;
continue;
}
if (args[argidx] == "-logic") {
config.logic_mode = true;
continue;
}
break;
}
extra_args(args, argidx, design);
for (auto module : design->selected_modules()) {
TribufWorker worker(module, config);
worker.run();
}
}
} TribufPass;
PRIVATE_NAMESPACE_END
|
