/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2020  Alberto Gonzalez <boqwxp@airmail.cc>
 *
 *  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/register.h"
#include "kernel/rtlil.h"
#include "kernel/log.h"

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

struct GliftPass : public Pass {
	private:

	bool opt_create, opt_taintconstants;
	std::vector<std::string> args;
	std::vector<std::string>::size_type argidx;
	RTLIL::Module *module;

	void parse_args() {
		for (argidx = 1; argidx < args.size(); argidx++) {
			if (args[argidx] == "-create") {
				opt_create = true;
				continue;
			}
			if (args[argidx] == "-taint-constants") {
				opt_taintconstants = true;
				continue;
			}
			break;
		}
	}

	RTLIL::SigSpec get_corresponding_taint_signal(RTLIL::SigSpec sig) {
		RTLIL::SigSpec ret;

		//Get the connected wire for the cell port:
		log_assert(sig.is_wire() || sig.is_fully_const());
		log_assert(sig.is_wire() || sig.is_fully_const());

		//Get a SigSpec for the corresponding taint signal for the cell port, creating one if necessary:
		if (sig.is_wire()) {
			RTLIL::Wire *w = module->wire(sig.as_wire()->name.str() + "_t");
			if (w == nullptr) w = module->addWire(sig.as_wire()->name.str() + "_t", 1);
			ret = w;
		}
		else if (sig.is_fully_const() && opt_taintconstants)
			ret = RTLIL::State::S1;
		else if (sig.is_fully_const())
			ret = RTLIL::State::S0;
		else
			log_cmd_error("Cell port SigSpec has unexpected type.\n");

		//Finally, if the cell port was a module input or output, make sure the corresponding taint signal is marked, too:
		if(sig.is_wire() && sig.as_wire()->port_input)
			ret.as_wire()->port_input = true;
		if(sig.is_wire() && sig.as_wire()->port_output)
			ret.as_wire()->port_output = true;

		return ret;
	}

	void create_precise_glift_logic() {
		std::vector<RTLIL::SigSig> connections(module->connections());
		std::vector<RTLIL::SigSig> new_connections;

		for(auto &cell : module->cells().to_vector()) {
			if (!cell->type.in("$_AND_", "$_OR_", "$_NOT_", "$anyconst", "$allconst", "$assume", "$assert")) {
				log_cmd_error("Invalid cell type \"%s\" found.  Module must be techmapped.\n", cell->type.c_str());
			}
			if (cell->type.in("$_AND_", "$_OR_")) {
				const unsigned int A = 0, B = 1, Y = 2;
				const unsigned int NUM_PORTS = 3;
				RTLIL::SigSpec ports[NUM_PORTS] = {cell->getPort(ID::A), cell->getPort(ID::B), cell->getPort(ID::Y)};
				RTLIL::SigSpec port_taints[NUM_PORTS];

				if (ports[A].size() != 1 || ports[B].size() != 1 || ports[Y].size() != 1)
					log_cmd_error("Multi-bit signal found.  Run `splitnets` first.\n");
				for (unsigned int i = 0; i < NUM_PORTS; ++i)
					port_taints[i] = get_corresponding_taint_signal(ports[i]);

				if (cell->type == "$_AND_") {
					//We are basically trying to replace each AND cell with an AN2_SH2 cell:
					//module AN2_SH2(A, A_t, B, B_t, Y, Y_t);
					//  input A, A_t, B, B_t;
					//  output Y, Y_t;
					//
					//  assign Y = A & B;
					//  assign Y_t = A & B_t | B & A_t | A_t & B_t;
					//endmodule
					auto subexpr1 = module->And(cell->name.str() + "_t_1", ports[A], port_taints[B], false, cell->get_src_attribute());
					auto subexpr2 = module->And(cell->name.str() + "_t_2", ports[B], port_taints[A], false, cell->get_src_attribute());
					auto subexpr3 = module->And(cell->name.str() + "_t_3", port_taints[A], port_taints[B], false, cell->get_src_attribute());
					auto subexpr4 = module->Or(cell->name.str() + "_t_4", subexpr1, subexpr2, false, cell->get_src_attribute());
					module->addOr(cell->name.str() + "_t_5", subexpr4, subexpr3, port_taints[Y], false, cell->get_src_attribute());
				}

				else if (cell->type == "$_OR_") {
					//We are basically trying to replace each OR cell with an OR2_SH2 cell:
					//module OR2_SH2(A, A_t, B, B_t, Y, Y_t);
					//  input A, A_t, B, B_t;
					//  output Y, Y_t;
					//
					//  assign Y = A | B;
					//  assign Y_t = ~A & B_t | ~B & A_t | A_t & B_t;
					//endmodule
					RTLIL::SigSpec n_port_a = module->LogicNot(cell->name.str() + "_t_1", ports[A], false, cell->get_src_attribute());
					RTLIL::SigSpec n_port_b = module->LogicNot(cell->name.str() + "_t_2", ports[B], false, cell->get_src_attribute());
					auto subexpr1 = module->And(cell->name.str() + "_t_3", n_port_a, port_taints[B], false, cell->get_src_attribute());
					auto subexpr2 = module->And(cell->name.str() + "_t_4", n_port_b, port_taints[A], false, cell->get_src_attribute());
					auto subexpr3 = module->And(cell->name.str() + "_t_5", port_taints[A], port_taints[B], false, cell->get_src_attribute());
					auto subexpr4 = module->Or(cell->name.str() + "_t_6", subexpr1, subexpr2, false, cell->get_src_attribute());
					module->addOr(cell->name.str() + "_t_7", subexpr4, subexpr3, port_taints[Y], false, cell->get_src_attribute());
				}

				else log_cmd_error("This is a bug (1).\n");
			}
			else if (cell->type.in("$_NOT_")) {
				const unsigned int A = 0, Y = 1;
				const unsigned int NUM_PORTS = 2;
				RTLIL::SigSpec ports[NUM_PORTS] = {cell->getPort(ID::A), cell->getPort(ID::Y)};
				RTLIL::SigSpec port_taints[NUM_PORTS];

				if (ports[A].size() != 1 || ports[Y].size() != 1)
					log_cmd_error("Multi-bit signal found.  Run `splitnets` first.\n");
				for (unsigned int i = 0; i < NUM_PORTS; ++i)
					port_taints[i] = get_corresponding_taint_signal(ports[i]);

				if (cell->type == "$_NOT_") {
					//We are basically trying to replace each NOT cell with an IV_SH2 cell:
					//module IV_SH2(A, A_t, Y, Y_t);
					//  input A, A_t;
					//  output Y, Y_t;
					//
					//  assign Y = ~A;
					//  assign Y_t = A_t;
					//endmodule
					new_connections.emplace_back(port_taints[Y], port_taints[A]);
				}
				else log_cmd_error("This is a bug (1).\n");
			}
		} //end foreach cell in cells

		for (auto &conn : connections) {
			RTLIL::SigSpec first = get_corresponding_taint_signal(conn.first);
			RTLIL::SigSpec second = get_corresponding_taint_signal(conn.second);

			module->connect(get_corresponding_taint_signal(conn.first), get_corresponding_taint_signal(conn.second));

			if(conn.second.is_wire() && conn.second.as_wire()->port_input)
				second.as_wire()->port_input = true;
			if(conn.first.is_wire() && conn.first.as_wire()->port_output)
				first.as_wire()->port_output = true;
		} //end foreach conn in connections

		for (auto &conn : new_connections)
			module->connect(conn);

		module->fixup_ports(); //we have some new taint signals in the module interface
	}

	public:

	GliftPass() : Pass("glift", "create and transform GLIFT models"), opt_create(false), opt_taintconstants(false), module(nullptr) { }
	void help() YS_OVERRIDE
	{
		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
		log("\n");
		log("    glift [options] [selection]\n");
		log("\n");
		log("Adds, removes, or manipulates gate-level information flow tracking (GLIFT) logic\n");
		log("to the current or specified module.\n");
		log("\n");
		log("Options:");
		log("\n");
		log("  -create");
		log("    Replaces the current or specified module with one that has additional \"taint\"\n");
		log("    inputs, outputs, and internal nets along with precise taint-tracking logic.\n");
		log("\n");
		log("  -taint-constants");
		log("    Constant values in the design are labeled as tainted.\n");
		log("    (default: label constants as un-tainted)\n");
		log("\n");
	}
	void execute(std::vector<std::string> _args, RTLIL::Design *design) YS_OVERRIDE
	{
		log_header(design, "Executing GLIFT pass (creating and manipulating GLIFT models).\n");

		args = _args;
		parse_args();
		extra_args(args, argidx, design);

		for (auto mod : design->selected_modules()) {
			if (module)
				log_cmd_error("Only one module may be selected for the glift pass! Flatten the design if necessary. (selected: %s and %s)\n", log_id(module), log_id(mod));
			module = mod;
		}
		if (module == nullptr)
			log_cmd_error("Can't operate on an empty selection!\n");

		if (opt_create)
			create_precise_glift_logic();
	}
} GliftPass;

PRIVATE_NAMESPACE_END