/*!
   \file M_Instruction.h
   \brief Decode M extensions part of the RISC-V
   \author Màrius Montón
   \date November 2018
*/

#ifndef M_INSTRUCTION__H
#define M_INSTRUCTION__H

#include "systemc"

using namespace sc_core;
using namespace sc_dt;
using namespace std;

typedef enum {
OP_M_MUL,
OP_M_MULH,
OP_M_MULHSU,
OP_M_MULHU,
OP_M_DIV,
OP_M_DIVU,
OP_M_REM,
OP_M_REMU,

OP_M_ERROR
} op_M_Codes;


typedef enum {
  M_MUL      = 0b000,
  M_MULH     = 0b001,
  M_MULHSU   = 0b010,
  M_MULHU    = 0b011,
  M_DIV      = 0b100,
  M_DIVU     = 0b101,
  M_REM      = 0b110,
  M_REMU     = 0b111,
} M_Codes;

/**
 * @brief Instruction decoding and fields access
 */
class M_Instruction{
public:

  /**
   * @brief Constructor
   * @param instr Instruction to decode
   */
  M_Instruction(sc_uint<32> instr);

  /**
   * @brief Access to opcode field
   * @return return opcode field
   */
  inline int32_t opcode() {
    return m_instr.range(14,12);
  }

  /**
   * @brief Access to rd field
   * @return rd field
   */
  inline int32_t get_rd() {
    return m_instr.range(11, 7);
  }

  inline void set_rd(int32_t value) {
    m_instr.range(11,7) = value;
  }


  /**
   * @brief Access to rs1 field
   * @return rs1 field
   */
  inline int32_t get_rs1() {
    return m_instr.range(19, 5);
  }

  inline void set_rs1(int32_t value) {
    m_instr.range(19,15) = value;
  }


  /**
   * @brief Access to rs2 field
   * @return rs2 field
   */
  inline int32_t get_rs2() {
    return m_instr.range(24, 20);
  }

  inline void set_rs2(int32_t value) {
    m_instr.range(24,20) = value;
  }


  inline int32_t get_funct3() {
    return m_instr.range(14, 12);
  }

  inline void set_funct3(int32_t value) {
    m_instr.range(14,12) = value;
  }

  /**
   * @brief Decodes opcode of instruction
   * @return opcode of instruction
   */
  op_M_Codes decode();

  inline void dump() {
    cout << hex << "0x" << m_instr << dec << endl;
  }
private:
  sc_uint<32> m_instr;
};

#endif