// Simulator for the RISC-V[ECTOR] mini-ISA
// Copyright (C) 2025 Siddarth Suresh
// Copyright (C) 2025 bdunahu

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#ifndef EX_H
#define EX_H
#include "instrDTO.h"
#include "response.h"
#include "stage.h"
#include <exception>
#include <unordered_map>

#define ADDITION_OF_GUARD(a, b) (b >= 0) && (a > MAX_INT - b)

#define ADDITION_UF_GUARD(a, b) (b < 0) && (a < (-(MAX_INT)-1) - b)

#define SUBTRACTION_OF_GUARD(a, b) (b < 0) && (a > MAX_INT + b)

#define SUBTRACTION_UF_GUARD(a, b) (b >= 0) && (a < (-(MAX_INT)-1) + b)

#define MULTIPLICATION_OF_GUARD(a, b)                                          \
	(b != 0) && (((b > 0) && (a > 0) && (a > MAX_INT / b)) ||                  \
				 ((b < 0) && (a < 0) && (a < MAX_INT / b)))

#define MULTIPLICATION_UF_GUARD(a, b)                                          \
	(b != 0) && (b != -1) &&                                                   \
		(((b > 0) && (a < 0) && (a < (-(MAX_INT)-1) / b)) ||                   \
		 ((b < 0) && (a > 0) && (a > (-(MAX_INT)-1) / b)))

#define DIVISION_OF_GUARD(a, b) ((a == -(MAX_INT)-1) && (b == -1)) || (b == 0)

class HaltException : public std::exception
{
	const char *what() const noexcept override { return ""; }
};

class EX : public Stage
{
  public:
	/**
	 * Constructor.
	 * @param The next stage in the pipeline.
	 * @return A newly allocated EX object.
	 */
	using Stage::advance;
	using Stage::Stage;

  private:
	void advance_helper();
	/**
	 * Handles operations involving three ints.
	 * @param slot 1, and later, the result of the mnemonic operation.
	 * @param slot 2
	 * @param slot 3
	 * @param the mnemonic
	 * @param the program counter
	 */
	void handle_int_operations(
		signed int &s1,
		signed int s2,
		signed int s3,
		Mnemonic m,
		unsigned int pc);
	/**
	 * Handles operations involving three vector registers.
	 * @param slot 1, and later, the result of the mnemonic operation.
	 * @param slot 2
	 * @param slot 3
	 * @param the mnemonic
	 * @param the vector length register
	 */
	void handle_vector_operations(
		std::array<signed int, V_R_LIMIT> &s1,
		std::array<signed int, V_R_LIMIT> s2,
		Mnemonic m,
		unsigned int v_len);

	/**
	 * Handles operations involving a single vector register.
	 * Currently, this is SRDL and SRDS
	 * @param slot 1, and later, the result of the mnemonic operation.
	 * @param slot 2
	 * @param the mnemonic
	 * @param the vector length register
	 */
	void handle_i_vector_operations(signed int &s1, signed int s2, Mnemonic m);
	/**
	 * Wrapper for division functions, which detects HALT instructinos (division
	 * by 0).
	 * @param the numerator
	 * @param the denominator
	 * @param if the modulo operator should instead be used
	 * @return if the operation overflowed
	 */
	bool handle_divide(signed int &s1, signed int s2, bool is_mod);
};

#endif /* EX_H_INCLUDED */