/*
 *  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 ZinitPass : public Pass {
	ZinitPass() : Pass("zinit", "add inverters so all FF are zero-initialized") { }
	void help() YS_OVERRIDE
	{
		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
		log("\n");
		log("    zinit [options] [selection]\n");
		log("\n");
		log("Add inverters as needed to make all FFs zero-initialized.\n");
		log("\n");
		log("    -all\n");
		log("        also add zero initialization to uninitialized FFs\n");
		log("\n");
	}
	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
	{
		bool all_mode = false;

		log_header(design, "Executing ZINIT pass (make all FFs zero-initialized).\n");

		size_t argidx;
		for (argidx = 1; argidx < args.size(); argidx++)
		{
			if (args[argidx] == "-singleton") {
				all_mode = true;
				continue;
			}
			break;
		}
		extra_args(args, argidx, design);

		for (auto module : design->selected_modules())
		{
			SigMap sigmap(module);
			dict<SigBit, State> initbits;
			pool<SigBit> donebits;

			for (auto wire : module->selected_wires())
			{
				if (wire->attributes.count("\\init") == 0)
					continue;

				SigSpec wirebits = sigmap(wire);
				Const initval = wire->attributes.at("\\init");
				wire->attributes.erase("\\init");

				for (int i = 0; i < GetSize(wirebits) && i < GetSize(initval); i++)
				{
					SigBit bit = wirebits[i];
					State val = initval[i];

					if (val != State::S0 && val != State::S1 && bit.wire != nullptr)
						continue;

					if (initbits.count(bit)) {
						if (initbits.at(bit) != val)
							log_error("Conflicting init values for signal %s (%s = %s != %s).\n",
									log_signal(bit), log_signal(SigBit(wire, i)),
									log_signal(val), log_signal(initbits.at(bit)));
						continue;
					}

					initbits[bit] = val;
				}
			}

			pool<IdString> dff_types = {
				"$ff", "$dff", "$dffe", "$dffsr", "$adff",
				"$_FF_", "$_DFFE_NN_", "$_DFFE_NP_", "$_DFFE_PN_", "$_DFFE_PP_",
				"$_DFFSR_NNN_", "$_DFFSR_NNP_", "$_DFFSR_NPN_", "$_DFFSR_NPP_",
				"$_DFFSR_PNN_", "$_DFFSR_PNP_", "$_DFFSR_PPN_", "$_DFFSR_PPP_",
				"$_DFF_N_", "$_DFF_NN0_", "$_DFF_NN1_", "$_DFF_NP0_", "$_DFF_NP1_",
				"$_DFF_P_", "$_DFF_PN0_", "$_DFF_PN1_", "$_DFF_PP0_", "$_DFF_PP1_"
			};

			for (auto cell : module->selected_cells())
			{
				if (!dff_types.count(cell->type))
					continue;

				SigSpec sig_d = sigmap(cell->getPort("\\D"));
				SigSpec sig_q = sigmap(cell->getPort("\\Q"));

				if (GetSize(sig_d) < 1 || GetSize(sig_q) < 1)
					continue;

				Const initval;

				for (int i = 0; i < GetSize(sig_q); i++) {
					if (initbits.count(sig_q[i])) {
						initval.bits.push_back(initbits.at(sig_q[i]));
						donebits.insert(sig_q[i]);
					} else
						initval.bits.push_back(all_mode ? State::S0 : State::Sx);
				}

				Wire *initwire = module->addWire(NEW_ID, GetSize(initval));
				initwire->attributes["\\init"] = initval;

				for (int i = 0; i < GetSize(initwire); i++)
					if (initval.bits.at(i) == State::S1)
					{
						sig_d[i] = module->NotGate(NEW_ID, sig_d[i]);
						module->addNotGate(NEW_ID, SigSpec(initwire, i), sig_q[i]);
						initwire->attributes["\\init"].bits.at(i) = State::S0;
					}
					else
					{
						module->connect(sig_q[i], SigSpec(initwire, i));
					}

				log("FF init value for cell %s (%s): %s = %s\n", log_id(cell), log_id(cell->type),
						log_signal(sig_q), log_signal(initval));

				cell->setPort("\\D", sig_d);
				cell->setPort("\\Q", initwire);
			}

			for (auto &it : initbits)
				if (donebits.count(it.first) == 0)
					log_error("Failed to handle init bit %s = %s.\n", log_signal(it.first), log_signal(it.second));
		}
	}
} ZinitPass;

PRIVATE_NAMESPACE_END