/*
 * Copyright 2020-2022 F4PGA Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 */

#include "kernel/sigtools.h"
#include "kernel/yosys.h"

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

#define MODE_BITS_REGISTER_INPUTS_ID 92
#define MODE_BITS_OUTPUT_SELECT_START_ID 81
#define MODE_BITS_OUTPUT_SELECT_WIDTH 3

// ============================================================================

struct QlDspIORegs : public Pass {

	const std::vector<std::string> ports2del_mult = {"load_acc", "subtract", "acc_fir", "dly_b"};
	const std::vector<std::string> ports2del_mult_acc = {"acc_fir", "dly_b"};
	const std::vector<std::string> ports2del_mult_add = {"dly_b"};
	const std::vector<std::string> ports2del_extension = {"saturate_enable", "shift_right", "round"};

	/// Temporary SigBit to SigBit helper map.
	SigMap m_SigMap;

	// ..........................................

	QlDspIORegs() : Pass("ql_dsp_io_regs", "Changes types of QL_DSP2/QL_DSP3 depending on their configuration.") {}

	void help() override
	{
		log("\n");
		log("    ql_dsp_io_regs [options] [selection]\n");
		log("\n");
		log("Looks for QL_DSP2/QL_DSP3 cells and changes their types depending\n");
		log("on their configuration.\n");
	}

	void execute(std::vector<std::string> a_Args, RTLIL::Design *a_Design) override
	{
		log_header(a_Design, "Executing QL_DSP_IO_REGS pass.\n");

		size_t argidx;
		for (argidx = 1; argidx < a_Args.size(); argidx++) {
			break;
		}
		extra_args(a_Args, argidx, a_Design);

		for (auto module : a_Design->selected_modules()) {
			ql_dsp_io_regs_pass(module);
		}
	}

	// Returns a pair of mask and value describing constant bit connections of
	// a SigSpec
	std::pair<uint32_t, uint32_t> get_constant_mask_value(const RTLIL::SigSpec *sigspec)
	{
		uint32_t mask = 0L;
		uint32_t value = 0L;

		auto sigbits = sigspec->bits();
		for (ssize_t i = (sigbits.size() - 1); i >= 0; --i) {
			auto other = m_SigMap(sigbits[i]);

			mask <<= 1;
			value <<= 1;

			// A known constant
			if (!other.is_wire() && other.data != RTLIL::Sx) {
				mask |= 0x1;
				value |= (other.data == RTLIL::S1);
			}
		}

		return std::make_pair(mask, value);
	}

	void ql_dsp_io_regs_pass(RTLIL::Module *module)
	{
		// Setup the SigMap
		m_SigMap.clear();
		m_SigMap.set(module);

		for (auto cell : module->cells_) {
			std::string cell_type = cell.second->type.str();
			if (cell_type == RTLIL::escape_id("QL_DSP2") || cell_type == RTLIL::escape_id("QL_DSP3")) {
				auto dsp = cell.second;

				// If the cell does not have the "is_inferred" attribute set
				// then don't touch it.
				if (!dsp->has_attribute(RTLIL::escape_id("is_inferred")) || dsp->get_bool_attribute(RTLIL::escape_id("is_inferred")) == false) {
					continue;
				}

				bool del_clk = true;
				bool use_dsp_cfg_params = (cell_type == RTLIL::escape_id("QL_DSP3"));

				int reg_in_i;
				int out_sel_i;

				// Get DSP configuration
				if (use_dsp_cfg_params) {
					// Read MODE_BITS at correct indexes
					auto mode_bits = &dsp->getParam(RTLIL::escape_id("MODE_BITS"));
					RTLIL::Const register_inputs;
					register_inputs = mode_bits->bits.at(MODE_BITS_REGISTER_INPUTS_ID);
					reg_in_i = register_inputs.as_int();

					RTLIL::Const output_select;
					output_select = mode_bits->extract(MODE_BITS_OUTPUT_SELECT_START_ID, MODE_BITS_OUTPUT_SELECT_WIDTH);
					out_sel_i = output_select.as_int();
				} else {
					// Read dedicated configuration ports
					const RTLIL::SigSpec *register_inputs;
					register_inputs = &dsp->getPort(RTLIL::escape_id("register_inputs"));
					if (!register_inputs)
						log_error("register_inputs port not found!");
					auto reg_in_c = register_inputs->as_const();
					reg_in_i = reg_in_c.as_int();

					const RTLIL::SigSpec *output_select;
					output_select = &dsp->getPort(RTLIL::escape_id("output_select"));
					if (!output_select)
						log_error("output_select port not found!");
					auto out_sel_c = output_select->as_const();
					out_sel_i = out_sel_c.as_int();
				}

				// Get the feedback port
				const RTLIL::SigSpec *feedback;
				feedback = &dsp->getPort(RTLIL::escape_id("feedback"));
				if (!feedback)
					log_error("feedback port not found!");

				// Check if feedback is or can be set to 0 which implies MACC
				auto feedback_con = get_constant_mask_value(feedback);
				bool have_macc = (feedback_con.second == 0x0);
				// log("mask=0x%08X value=0x%08X\n", consts.first, consts.second);
				// log_error("=== END HERE ===\n");

				// Build new type name
				std::string new_type = cell_type;
				new_type += "_MULT";

				if (have_macc) {
					switch (out_sel_i) {
					case 1:
					case 2:
					case 3:
					case 5:
					case 7:
						del_clk = false;
						new_type += "ACC";
						break;
					default:
						break;
					}
				} else {
					switch (out_sel_i) {
					case 1:
					case 2:
					case 3:
					case 5:
					case 7:
						new_type += "ADD";
						break;
					default:
						break;
					}
				}

				if (reg_in_i) {
					del_clk = false;
					new_type += "_REGIN";
				}

				if (out_sel_i > 3) {
					del_clk = false;
					new_type += "_REGOUT";
				}

				// Set new type name
				dsp->type = RTLIL::IdString(new_type);

				std::vector<std::string> ports2del;

				if (del_clk)
					ports2del.push_back("clk");

				switch (out_sel_i) {
				case 0:
				case 4:
				case 6:
					ports2del.insert(ports2del.end(), ports2del_mult.begin(), ports2del_mult.end());
					// Mark for deleton additional configuration ports
					if (!use_dsp_cfg_params) {
						ports2del.insert(ports2del.end(), ports2del_extension.begin(), ports2del_extension.end());
					}
					break;
				case 1:
				case 2:
				case 3:
				case 5:
				case 7:
					if (have_macc) {
						ports2del.insert(ports2del.end(), ports2del_mult_acc.begin(), ports2del_mult_acc.end());
					} else {
						ports2del.insert(ports2del.end(), ports2del_mult_add.begin(), ports2del_mult_add.end());
					}
					break;
				}

				for (auto portname : ports2del) {
					const RTLIL::SigSpec *port = &dsp->getPort(RTLIL::escape_id(portname));
					if (!port)
						log_error("%s port not found!", portname.c_str());
					dsp->connections_.erase(RTLIL::escape_id(portname));
				}
			}
		}

		// Clear the sigmap
		m_SigMap.clear();
	}

} QlDspIORegs;

PRIVATE_NAMESPACE_END