/*!
   \file Instruction.h
   \brief Decode instructions part of the RISC-V
   \author Màrius Montón
   \date August 2018
*/

#ifndef INSTRUCTION__H
#define INSTRUCTION__H

#include "systemc"

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

typedef enum {
  BASE_EXTENSION,
  M_EXTENSION,
  A_EXTENSION,
  F_EXTENSION,
  D_EXTENSION,
  Q_EXTENSION,
  L_EXTENSION,
  C_EXTENSION,
  R_EXTENSION,
  J_EXTENSION,
  P_EXTENSION,
  V_EXTENSION,
  N_EXTENSION,
  UNKNOWN_EXTENSION
} extension_t;

typedef enum {
OP_LUI,
OP_AUIPC,
OP_JAL,
OP_JALR,

OP_BEQ,
OP_BNE,
OP_BLT,
OP_BGE,
OP_BLTU,
OP_BGEU,

OP_LB,
OP_LH,
OP_LW,
OP_LBU,
OP_LHU,

OP_SB,
OP_SH,
OP_SW,

OP_ADDI,
OP_SLTI,
OP_SLTIU,
OP_XORI,
OP_ORI,
OP_ANDI,
OP_SLLI,
OP_SRLI,
OP_SRAI,

OP_ADD,
OP_SUB,
OP_SLL,
OP_SLT,
OP_SLTU,
OP_XOR,
OP_SRL,
OP_SRA,
OP_OR,
OP_AND,

OP_FENCE,
OP_ECALL,
OP_EBREAK,

OP_CSRRW,
OP_CSRRS,
OP_CSRRC,
OP_CSRRWI,
OP_CSRRSI,
OP_CSRRCI,

OP_URET,
OP_SRET,
OP_MRET,
OP_WFI,
OP_SFENCE,

OP_ERROR
} opCodes;


typedef enum {
  LUI     = 0b0110111,
  AUIPC   = 0b0010111,
  JAL     = 0b1101111,
  JALR    = 0b1100111,

  BEQ     = 0b1100011,
  BEQ_F   = 0b000,
  BNE_F   = 0b001,
  BLT_F   = 0b100,
  BGE_F   = 0b101,
  BLTU_F  = 0b110,
  BGEU_F  = 0b111,

  LB      = 0b0000011,
  LB_F    = 0b000,
  LH_F    = 0b001,
  LW_F    = 0b010,
  LBU_F   = 0b100,
  LHU_F   = 0b101,

  SB      = 0b0100011,
  SB_F    = 0b000,
  SH_F    = 0b001,
  SW_F    = 0b010,

  ADDI    = 0b0010011,
  ADDI_F  = 0b000,
  SLTI_F  = 0b010,
  SLTIU_F = 0b011,
  XORI_F  = 0b100,
  ORI_F   = 0b110,
  ANDI_F  = 0b111,
  SLLI_F  = 0b001,
  SRLI_F  = 0b101,
  SRLI_F7 = 0b0000000,
  SRAI_F7 = 0b0100000,

  ADD     = 0b0110011,
  ADD_F   = 0b000,
  SUB_F   = 0b000,
  ADD_F7  = 0b0000000,
  SUB_F7  = 0b0100000,

  SLL_F   = 0b001,
  SLT_F   = 0b010,
  SLTU_F  = 0b011,
  XOR_F   = 0b100,
  SRL_F   = 0b101,
  SRA_F   = 0b101,
  SRL_F7  = 0b0000000,
  SRA_F7  = 0b0100000,
  OR_F    = 0b110,
  AND_F   = 0b111,

  FENCE   = 0b0001111,
  ECALL   = 0b1110011,
  ECALL_F = 0b000000000000,
  EBREAK_F= 0b000000000001,
  URET_F  = 0b000000000010,
  SRET_F  = 0b000100000010,
  MRET_F  = 0b001100000010,
  WFI_F   = 0b000100000101,
  SFENCE_F = 0b0001001,

  ECALL_F3= 0b000,
  CSRRW   = 0b001,
  CSRRS   = 0b010,
  CSRRC   = 0b011,
  CSRRWI  = 0b101,
  CSRRSI  = 0b110,
  CSRRCI  = 0b111,
} Codes;

#define EXCEPTION_CAUSE_INSTRUCTION_MISALIGN  0
#define EXCEPTION_CAUSE_INSTRUCTION_ACCESS    1
#define EXCEPTION_CAUSE_ILLEGAL_INSTRUCTION   2
#define EXCEPTION_CAUSE_BREAKPOINT            3
#define EXCEPTION_CAUSE_LOAD_ADDR_MISALIGN    4
#define EXCEPTION_CAUSE_LOAD_ACCESS_FAULT     5

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

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

  /**
   * @brief Access to opcode field
   * @return return opcode field
   */
  inline int32_t opcode() {
    return m_instr.range(6,0);
  }

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

  /**
   * @brief Sets rd field
   * @param value desired rd value
   */
  inline void set_rd(int32_t value) {
    m_instr.range(11,7) = value;
  }

  /**
   * @brief Access to funct3 field
   * @return funct3 field
   */
  inline int32_t get_funct3() {
    return m_instr.range(14, 12);
  }

  /**
   * @brief Sets func3 field
   * @param value desired func3 value
   */
  inline void set_funct3(int32_t value) {
    m_instr.range(14,12) = value;
  }

  /**
   * @brief Access to rs1 field
   * @return rs1 field
   */
  inline int32_t get_rs1() {
    return m_instr.range(19, 15);
  }

  /**
   * @brief Sets rs1 field
   * @param value desired rs1 value
   */
  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);
  }

  /**
   * @brief Sets rs2 field
   * @param value desired rs2 value
   */
  inline void set_rs2(int32_t value) {
    m_instr.range(24,10) = value;
  }

  /**
   * @brief Access to funct7 field
   * @return funct7 field
   */
  inline int32_t get_funct7() {
    return m_instr.range(31, 25);
  }

  /**
   * @brief Sets func7 field
   * @param value desired func7 value
   */
  inline void set_func7(int32_t value) {
    m_instr.range(31,25) = value;
  }

  /**
   * @brief Gets immediate field value for I-type
   * @return immediate_I field
   */
  inline int32_t get_imm_I() {
    int32_t aux = 0;

    aux = m_instr.range(31, 20);

    /* sign extension (optimize) */
    if (m_instr[31] == 1) {
      aux |= (0b11111111111111111111) << 12;
    }

    return aux;
  }

  /**
   * @brief Sets immediate field for I-type
   * @param value desired I value
   */
  inline void set_imm_I(int32_t value) {
    m_instr.range(31,20) = value;
  }

  /**
   * @brief Gets immediate field value for S-type
   * @return immediate_S field
   */
  inline int32_t get_imm_S() {
    int32_t aux = 0;

    aux  = m_instr.range(31, 25) << 5;
    aux |= m_instr.range(11,7);

    if (m_instr[31] == 1) {
      aux |= (0b11111111111111111111) << 12;
    }

    return aux;
  }

  /**
   * @brief Sets immediate field for S-type
   * @param value desired S value
   */
  inline void set_imm_S(int32_t value) {
    sc_uint<32> aux = value;

    m_instr.range(31,25) = aux.range(11,5);
    m_instr.range(11,7) = aux.range(4,0);
  }

  /**
   * @brief Gets immediate field value for U-type
   * @return immediate_U field
   */
  inline int32_t get_imm_U() {
    return m_instr.range(31, 12);
  }

  /**
   * @brief Sets immediate field for U-type
   * @param value desired U value
   */
  inline void set_imm_U(int32_t value) {
    m_instr.range(31,12) = (value << 12);
  }

  /**
   * @brief Gets immediate field value for B-type
   * @return immediate_B field
   */
  inline int32_t get_imm_B() {
    int32_t aux = 0;

    aux |= m_instr[7] << 11;
    aux |= m_instr.range(30, 25) << 5;
    aux |= m_instr[31] << 12;
    aux |= m_instr.range(11, 8) << 1;

    if (m_instr[31] == 1) {
      aux |= (0b11111111111111111111) << 12;
    }

    return aux;
  }

  /**
   * @brief Sets immediate field for B-type
   * @param value desired B value
   */
  inline void set_imm_B(int32_t value) {
    sc_uint<32> aux = value;

    m_instr[31] = aux[12];
    m_instr.range(30,25) = aux.range(10,5);
    m_instr.range(11,7) = aux.range(4,1);
    m_instr[6] = aux[11];
  }

  /**
   * @brief Gets immediate field value for J-type
   * @return immediate_J field
   */
  inline int32_t get_imm_J() {
    int32_t aux = 0;

    aux = m_instr[31] << 20;
    aux |= m_instr.range(19,12) << 12;
    aux |= m_instr[20] << 11;
    aux |= m_instr.range(30,21) << 1;

    /* bit extension (better way to do that?) */
    if (m_instr[31] == 1) {
      aux |= (0b111111111111) << 20;
    }

    return aux;
  }

  /**
   * @brief Sets immediate field for J-type
   * @param value desired J value
   */
  inline void set_imm_J(int32_t value) {
    sc_uint<32> aux = (value << 20);

    m_instr[31] = aux[20];
    m_instr.range(30,21) = aux.range(10,1);
    m_instr[20] = aux[11];
    m_instr.range(19,12) = aux.range(19,12);
  }

  /**
   * @brief Returns shamt field for Shifts instructions
   * @return value corresponding to inst(25:20)
   */
  inline int32_t get_shamt() {
    return m_instr.range(25, 20);
  }

  /**
   * @brief Returns CSR field for CSR instructions
   * @return value corresponding to instr(31:20)
   */
  inline int32_t get_csr() {
    int32_t aux = 0;

    aux = m_instr.range(31, 20);

    return aux;
  }

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

  /**
   * @brief returns what instruction extension
   * @return extension
   */
  extension_t check_extension();


  void setInstr(uint32_t p_instr) {
      m_instr = p_instr;
  }
  /**
   * @brief return instruction
   * @return all instruction bits (31:0)
   */
  uint32_t getInstr() {
    return m_instr;
  }


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

#endif