/*******************************************************************************
 * Copyright (C) 2021 MINRES Technologies GmbH
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Contributors:
 *       eyck@minres.com - initial implementation
 ******************************************************************************/

#ifndef _RISCV_HART_M_P_H
#define _RISCV_HART_M_P_H

#include "riscv_hart_common.h"
#include "iss/arch/traits.h"
#include "iss/instrumentation_if.h"
#include "iss/log_categories.h"
#include "iss/vm_if.h"
#ifndef FMT_HEADER_ONLY
#define FMT_HEADER_ONLY
#endif
#include <array>
#include <elfio/elfio.hpp>
#include <fmt/format.h>
#include <iomanip>
#include <sstream>
#include <type_traits>
#include <unordered_map>
#include <functional>
#include <util/bit_field.h>
#include <util/ities.h>
#include <util/sparse_array.h>

#if defined(__GNUC__)
#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
#else
#define likely(x) x
#define unlikely(x) x
#endif

namespace iss {
namespace arch {

template <typename BASE> class riscv_hart_m_p : public BASE {
protected:
    const std::array<const char, 4> lvl = {{'U', 'S', 'H', 'M'}};
    const std::array<const char *, 16> trap_str = {{""
                                              "Instruction address misaligned", // 0
                                              "Instruction access fault",       // 1
                                              "Illegal instruction",            // 2
                                              "Breakpoint",                     // 3
                                              "Load address misaligned",        // 4
                                              "Load access fault",              // 5
                                              "Store/AMO address misaligned",   // 6
                                              "Store/AMO access fault",         // 7
                                              "Environment call from U-mode",   // 8
                                              "Environment call from S-mode",   // 9
                                              "Reserved",                       // a
                                              "Environment call from M-mode",   // b
                                              "Instruction page fault",         // c
                                              "Load page fault",                // d
                                              "Reserved",                       // e
                                              "Store/AMO page fault"}};
    const std::array<const char *, 12> irq_str = {
        {"User software interrupt", "Supervisor software interrupt", "Reserved", "Machine software interrupt",
         "User timer interrupt", "Supervisor timer interrupt", "Reserved", "Machine timer interrupt",
         "User external interrupt", "Supervisor external interrupt", "Reserved", "Machine external interrupt"}};
public:
    using core = BASE;
    using this_class = riscv_hart_m_p<BASE>;
    using phys_addr_t = typename core::phys_addr_t;
    using reg_t = typename core::reg_t;
    using addr_t = typename core::addr_t;

    using rd_csr_f = iss::status (this_class::*)(unsigned addr, reg_t &);
    using wr_csr_f = iss::status (this_class::*)(unsigned addr, reg_t);

    // primary template
    template <class T, class Enable = void> struct hart_state {};
    // specialization 32bit
    template <typename T> class hart_state<T, typename std::enable_if<std::is_same<T, uint32_t>::value>::type> {
    public:
        BEGIN_BF_DECL(mstatus_t, T);
        // SD bit is read-only and is set when either the FS or XS bits encode a Dirty state (i.e., SD=((FS==11) OR XS==11)))
        BF_FIELD(SD, 31, 1);
        // Trap SRET
        BF_FIELD(TSR, 22, 1);
        // Timeout Wait
        BF_FIELD(TW, 21, 1);
        // Trap Virtual Memory
        BF_FIELD(TVM, 20, 1);
        // Make eXecutable Readable
        BF_FIELD(MXR, 19, 1);
        // permit Supervisor User Memory access
        BF_FIELD(SUM, 18, 1);
        // Modify PRiVilege
        BF_FIELD(MPRV, 17, 1);
        // status of additional user-mode extensions and associated state, All off/None dirty or clean, some on/None dirty, some clean/Some dirty
        BF_FIELD(XS, 15, 2);
        // floating-point unit status Off/Initial/Clean/Dirty
        BF_FIELD(FS, 13, 2);
        // machine previous privilege
        BF_FIELD(MPP, 11, 2);
        // supervisor previous privilege
        BF_FIELD(SPP, 8, 1);
        // previous machine interrupt-enable
        BF_FIELD(MPIE, 7, 1);
        // previous supervisor interrupt-enable
        BF_FIELD(SPIE, 5, 1);
        // previous user interrupt-enable
        BF_FIELD(UPIE, 4, 1);
        // machine interrupt-enable
        BF_FIELD(MIE, 3, 1);
        // supervisor interrupt-enable
        BF_FIELD(SIE, 1, 1);
        // user interrupt-enable
        BF_FIELD(UIE, 0, 1);
        END_BF_DECL();

        mstatus_t mstatus;

        static const reg_t mstatus_reset_val = 0;

        void write_mstatus(T val) {
            auto mask = get_mask();
            auto new_val = (mstatus.backing.val & ~mask) | (val & mask);
            mstatus = new_val;
        }

        T satp;

        static constexpr uint32_t get_mask() {
            return 0x807ff9ddUL; // 0b1000 0000 0111 1111 1111 1001 1011 1011  // only machine mode is supported
        }
    };
    using hart_state_type = hart_state<reg_t>;

    constexpr reg_t get_irq_mask() {
        return 0b101110111011; // only machine mode is supported
    }

    riscv_hart_m_p();
    virtual ~riscv_hart_m_p() = default;

    void reset(uint64_t address) override;

    std::pair<uint64_t, bool> load_file(std::string name, int type = -1) override;

    iss::status read(const address_type type, const access_type access, const uint32_t space,
            const uint64_t addr, const unsigned length, uint8_t *const data) override;
    iss::status write(const address_type type, const access_type access, const uint32_t space,
            const uint64_t addr, const unsigned length, const uint8_t *const data) override;

    virtual uint64_t enter_trap(uint64_t flags) override { return riscv_hart_m_p::enter_trap(flags, fault_data, fault_data); }
    virtual uint64_t enter_trap(uint64_t flags, uint64_t addr, uint64_t instr) override;
    virtual uint64_t leave_trap(uint64_t flags) override;

    const reg_t& get_mhartid() const { return mhartid_reg;	}
	void set_mhartid(reg_t mhartid) { mhartid_reg = mhartid; };

    void disass_output(uint64_t pc, const std::string instr) override {
        CLOG(INFO, disass) << fmt::format("0x{:016x}    {:40} [s:0x{:x};c:{}]",
                pc, instr, (reg_t)state.mstatus, this->reg.icount);
    };

    iss::instrumentation_if *get_instrumentation_if() override { return &instr_if; }

    void setMemReadCb(std::function<iss::status(phys_addr_t, unsigned, uint8_t* const)> const& memReadCb) {
        mem_read_cb = memReadCb;
    }

    void setMemWriteCb(std::function<iss::status(phys_addr_t, unsigned, const uint8_t* const)> const& memWriteCb) {
        mem_write_cb = memWriteCb;
    }

    void set_csr(unsigned addr, reg_t val){
        csr[addr & csr.page_addr_mask] = val;
    }

protected:
    struct riscv_instrumentation_if : public iss::instrumentation_if {

        riscv_instrumentation_if(riscv_hart_m_p<BASE> &arch)
        : arch(arch) {}
        /**
         * get the name of this architecture
         *
         * @return the name of this architecture
         */
        const std::string core_type_name() const override { return traits<BASE>::core_type; }

        virtual uint64_t get_pc() { return arch.get_pc(); };

        virtual uint64_t get_next_pc() { return arch.get_next_pc(); };

        virtual void set_curr_instr_cycles(unsigned cycles) { arch.cycle_offset += cycles - 1; };

        riscv_hart_m_p<BASE> &arch;
    };

    friend struct riscv_instrumentation_if;
    addr_t get_pc() { return this->reg.PC; }
    addr_t get_next_pc() { return this->reg.NEXT_PC; }

    virtual iss::status read_mem(phys_addr_t addr, unsigned length, uint8_t *const data);
    virtual iss::status write_mem(phys_addr_t addr, unsigned length, const uint8_t *const data);

    virtual iss::status read_csr(unsigned addr, reg_t &val);
    virtual iss::status write_csr(unsigned addr, reg_t val);

    hart_state_type state;
    int64_t cycle_offset{0};
    uint64_t mcycle_csr{0};
    int64_t instret_offset{0};
    uint64_t minstret_csr{0};
    reg_t fault_data;
    uint64_t tohost = tohost_dflt;
    uint64_t fromhost = fromhost_dflt;
    unsigned to_host_wr_cnt = 0;
    riscv_instrumentation_if instr_if;

    using mem_type = util::sparse_array<uint8_t, 1ULL << 32>;
    using csr_type = util::sparse_array<typename traits<BASE>::reg_t, 1ULL << 12, 12>;
    using csr_page_type = typename csr_type::page_type;
    mem_type mem;
    csr_type csr;
    std::stringstream uart_buf;
    std::unordered_map<reg_t, uint64_t> ptw;
    std::unordered_map<uint64_t, uint8_t> atomic_reservation;
    std::unordered_map<unsigned, rd_csr_f> csr_rd_cb;
    std::unordered_map<unsigned, wr_csr_f> csr_wr_cb;

private:
    iss::status read_reg(unsigned addr, reg_t &val);
    iss::status write_reg(unsigned addr, reg_t val);
    iss::status read_null(unsigned addr, reg_t &val);
    iss::status write_null(unsigned addr, reg_t val){return iss::status::Ok;}
    iss::status read_cycle(unsigned addr, reg_t &val);
    iss::status write_cycle(unsigned addr, reg_t val);
    iss::status read_instret(unsigned addr, reg_t &val);
    iss::status write_instret(unsigned addr, reg_t val);
    iss::status read_mtvec(unsigned addr, reg_t &val);
    iss::status read_time(unsigned addr, reg_t &val);
    iss::status read_status(unsigned addr, reg_t &val);
    iss::status write_status(unsigned addr, reg_t val);
    iss::status read_ie(unsigned addr, reg_t &val);
    iss::status write_ie(unsigned addr, reg_t val);
    iss::status read_ip(unsigned addr, reg_t &val);
    iss::status write_ip(unsigned addr, reg_t val);
    iss::status read_hartid(unsigned addr, reg_t &val);

    reg_t mhartid_reg{0x0};
    std::function<iss::status(phys_addr_t, unsigned, uint8_t *const)>mem_read_cb;
    std::function<iss::status(phys_addr_t, unsigned, const uint8_t *const)> mem_write_cb;

protected:
    void check_interrupt();
};

template <typename BASE>
riscv_hart_m_p<BASE>::riscv_hart_m_p()
: state()
, instr_if(*this) {
    csr[misa] = traits<BASE>::MISA_VAL;
    uart_buf.str("");
    for (unsigned addr = mhpmcounter3; addr <= mhpmcounter31; ++addr){
        csr_rd_cb[addr] = &this_class::read_null;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    for (unsigned addr = mhpmcounter3h; addr <= mhpmcounter31h; ++addr){
        csr_rd_cb[addr] = &this_class::read_null;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    for (unsigned addr = mhpmevent3; addr <= mhpmevent31; ++addr){
        csr_rd_cb[addr] = &this_class::read_null;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    for (unsigned addr = cycle; addr <= hpmcounter31; ++addr){
        csr_rd_cb[addr] = &this_class::read_null;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    for (unsigned addr = cycleh; addr <= hpmcounter31h; ++addr){
        csr_rd_cb[addr] = &this_class::read_null;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    // common regs
    const std::array<unsigned, 7> addrs{{misa, mepc, mtvec, mscratch, mcause, mtval, mscratch}};
    for(auto addr: addrs) {
        csr_rd_cb[addr] = &this_class::read_reg;
        csr_wr_cb[addr] = &this_class::write_reg;
    }
    // special handling & overrides
    csr_rd_cb[time] = &this_class::read_time;
    csr_wr_cb[time] = nullptr;
    csr_rd_cb[timeh] = &this_class::read_time;
    csr_wr_cb[timeh] = nullptr;
    csr_rd_cb[mcycle] = &this_class::read_cycle;
    csr_wr_cb[mcycle] = &this_class::write_cycle;
    csr_rd_cb[mcycleh] = &this_class::read_cycle;
    csr_wr_cb[mcycleh] = &this_class::write_cycle;
    csr_rd_cb[minstret] = &this_class::read_instret;
    csr_wr_cb[minstret] = &this_class::write_instret;
    csr_rd_cb[minstreth] = &this_class::read_instret;
    csr_wr_cb[minstreth] = &this_class::write_instret;
    csr_rd_cb[mstatus] = &this_class::read_status;
    csr_wr_cb[mstatus] = &this_class::write_status;
    csr_rd_cb[mip] = &this_class::read_ip;
    csr_wr_cb[mip] = &this_class::write_ip;
    csr_rd_cb[mie] = &this_class::read_ie;
    csr_wr_cb[mie] = &this_class::write_ie;
    csr_rd_cb[mhartid] = &this_class::read_hartid;
    csr_rd_cb[mcounteren] = &this_class::read_null;
    csr_wr_cb[mcounteren] = &this_class::write_null;
    csr_rd_cb[mtvec] = &this_class::read_mtvec;
    csr_wr_cb[misa] = &this_class::write_null;
}

template <typename BASE> std::pair<uint64_t, bool> riscv_hart_m_p<BASE>::load_file(std::string name, int type) {
    FILE *fp = fopen(name.c_str(), "r");
    if (fp) {
        std::array<char, 5> buf;
        auto n = fread(buf.data(), 1, 4, fp);
        if (n != 4) throw std::runtime_error("input file has insufficient size");
        buf[4] = 0;
        if (strcmp(buf.data() + 1, "ELF") == 0) {
            fclose(fp);
            // Create elfio reader
            ELFIO::elfio reader;
            // Load ELF data
            if (!reader.load(name)) throw std::runtime_error("could not process elf file");
            // check elf properties
            if (reader.get_class() != ELFCLASS32)
                if (sizeof(reg_t) == 4) throw std::runtime_error("wrong elf class in file");
            if (reader.get_type() != ET_EXEC) throw std::runtime_error("wrong elf type in file");
            if (reader.get_machine() != EM_RISCV) throw std::runtime_error("wrong elf machine in file");
            for (const auto pseg : reader.segments) {
                const auto fsize = pseg->get_file_size(); // 0x42c/0x0
                const auto seg_data = pseg->get_data();
                if (fsize > 0) {
                    auto res = this->write(iss::address_type::PHYSICAL, iss::access_type::DEBUG_WRITE,
                            traits<BASE>::MEM, pseg->get_physical_address(),
                            fsize, reinterpret_cast<const uint8_t *const>(seg_data));
                    if (res != iss::Ok)
                        LOG(ERROR) << "problem writing " << fsize << "bytes to 0x" << std::hex
                                   << pseg->get_physical_address();
                }
            }
            for (const auto sec : reader.sections) {
                if (sec->get_name() == ".tohost") {
                    tohost = sec->get_address();
                    fromhost = tohost + 0x40;
                }
            }

            return std::make_pair(reader.get_entry(), true);
        }
        throw std::runtime_error("memory load file is not a valid elf file");
    }
    throw std::runtime_error("memory load file not found");
}

template <typename BASE>
iss::status riscv_hart_m_p<BASE>::read(const address_type type, const access_type access, const uint32_t space,
        const uint64_t addr, const unsigned length, uint8_t *const data) {
#ifndef NDEBUG
    if (access && iss::access_type::DEBUG) {
        LOG(TRACEALL) << "debug read of " << length << " bytes @addr 0x" << std::hex << addr;
    } else if(access && iss::access_type::FETCH){
        LOG(TRACEALL) << "fetch of " << length << " bytes  @addr 0x" << std::hex << addr;
    } else {
        LOG(TRACE) << "read of " << length << " bytes  @addr 0x" << std::hex << addr;
   }
#endif
    try {
        switch (space) {
        case traits<BASE>::MEM: {
            if (unlikely((access == iss::access_type::FETCH || access == iss::access_type::DEBUG_FETCH) && (addr & 0x1) == 1)) {
                fault_data = addr;
                if (access && iss::access_type::DEBUG) throw trap_access(0, addr);
                this->reg.trap_state = (1 << 31); // issue trap 0
                return iss::Err;
            }
            try {
                auto res = type==iss::address_type::PHYSICAL?
                        read_mem( BASE::v2p(phys_addr_t{access, space, addr}), length, data):
                        read_mem( BASE::v2p(iss::addr_t{access, type, space, addr}), length, data);
                if (unlikely(res != iss::Ok)) this->reg.trap_state = (1 << 31) | (5 << 16); // issue trap 5 (load access fault
                return res;
            } catch (trap_access &ta) {
                this->reg.trap_state = (1 << 31) | ta.id;
                return iss::Err;
            }
        } break;
        case traits<BASE>::CSR: {
            if (length != sizeof(reg_t)) return iss::Err;
            return read_csr(addr, *reinterpret_cast<reg_t *const>(data));
        } break;
        case traits<BASE>::FENCE: {
            if ((addr + length) > mem.size()) return iss::Err;
            return iss::Ok;
        } break;
        case traits<BASE>::RES: {
            auto it = atomic_reservation.find(addr);
            if (it != atomic_reservation.end() && it->second != 0) {
                memset(data, 0xff, length);
                atomic_reservation.erase(addr);
            } else
                memset(data, 0, length);
        } break;
        default:
            return iss::Err; // assert("Not supported");
        }
        return iss::Ok;
    } catch (trap_access &ta) {
        this->reg.trap_state = (1 << 31) | ta.id;
        return iss::Err;
    }
}

template <typename BASE>
iss::status riscv_hart_m_p<BASE>::write(const address_type type, const access_type access, const uint32_t space,
        const uint64_t addr, const unsigned length, const uint8_t *const data) {
#ifndef NDEBUG
    const char *prefix = (access && iss::access_type::DEBUG) ? "debug " : "";
    switch (length) {
    case 8:
        LOG(TRACE) << prefix << "write of " << length << " bytes (0x" << std::hex << *(uint64_t *)&data[0] << std::dec
                   << ") @addr 0x" << std::hex << addr;
        break;
    case 4:
        LOG(TRACE) << prefix << "write of " << length << " bytes (0x" << std::hex << *(uint32_t *)&data[0] << std::dec
                   << ") @addr 0x" << std::hex << addr;
        break;
    case 2:
        LOG(TRACE) << prefix << "write of " << length << " bytes (0x" << std::hex << *(uint16_t *)&data[0] << std::dec
                   << ") @addr 0x" << std::hex << addr;
        break;
    case 1:
        LOG(TRACE) << prefix << "write of " << length << " bytes (0x" << std::hex << (uint16_t)data[0] << std::dec
                   << ") @addr 0x" << std::hex << addr;
        break;
    default:
        LOG(TRACE) << prefix << "write of " << length << " bytes @addr " << addr;
    }
#endif
    try {
        switch (space) {
        case traits<BASE>::MEM: {
            if (unlikely((access && iss::access_type::FETCH) && (addr & 0x1) == 1)) {
                fault_data = addr;
                if (access && iss::access_type::DEBUG) throw trap_access(0, addr);
                this->reg.trap_state = (1 << 31); // issue trap 0
                return iss::Err;
            }
            try {
                auto res = type==iss::address_type::PHYSICAL?
                        write_mem(phys_addr_t{access, space, addr}, length, data):
                        write_mem(BASE::v2p(iss::addr_t{access, type, space, addr}), length, data);
                if (unlikely(res != iss::Ok))
                    this->reg.trap_state = (1 << 31) | (5 << 16); // issue trap 7 (Store/AMO access fault)
                return res;
            } catch (trap_access &ta) {
                this->reg.trap_state = (1 << 31) | ta.id;
                return iss::Err;
            }

            phys_addr_t paddr = BASE::v2p(iss::addr_t{access, type, space, addr});
            if ((paddr.val + length) > mem.size()) return iss::Err;
            switch (paddr.val) {
            case 0x10013000: // UART0 base, TXFIFO reg
            case 0x10023000: // UART1 base, TXFIFO reg
                uart_buf << (char)data[0];
                if (((char)data[0]) == '\n' || data[0] == 0) {
                    // LOG(INFO)<<"UART"<<((paddr.val>>16)&0x3)<<" send
                    // '"<<uart_buf.str()<<"'";
                    std::cout << uart_buf.str();
                    uart_buf.str("");
                }
                return iss::Ok;
            case 0x10008000: { // HFROSC base, hfrosccfg reg
                auto &p = mem(paddr.val / mem.page_size);
                auto offs = paddr.val & mem.page_addr_mask;
                std::copy(data, data + length, p.data() + offs);
                auto &x = *(p.data() + offs + 3);
                if (x & 0x40) x |= 0x80; // hfroscrdy = 1 if hfroscen==1
                return iss::Ok;
            }
            case 0x10008008: { // HFROSC base, pllcfg reg
                auto &p = mem(paddr.val / mem.page_size);
                auto offs = paddr.val & mem.page_addr_mask;
                std::copy(data, data + length, p.data() + offs);
                auto &x = *(p.data() + offs + 3);
                x |= 0x80; // set pll lock upon writing
                return iss::Ok;
            } break;
            default: {}
            }
        } break;
        case traits<BASE>::CSR: {
            if (length != sizeof(reg_t)) return iss::Err;
            return write_csr(addr, *reinterpret_cast<const reg_t *>(data));
        } break;
        case traits<BASE>::FENCE: {
            if ((addr + length) > mem.size()) return iss::Err;
            switch (addr) {
            case 2:
            case 3: {
                ptw.clear();
                auto tvm = state.mstatus.TVM;
                return iss::Ok;
            }
            }
        } break;
        case traits<BASE>::RES: {
            atomic_reservation[addr] = data[0];
        } break;
        default:
            return iss::Err;
        }
        return iss::Ok;
    } catch (trap_access &ta) {
        this->reg.trap_state = (1 << 31) | ta.id;
        return iss::Err;
    }
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_csr(unsigned addr, reg_t &val) {
    if (addr >= csr.size()) return iss::Err;
    auto req_priv_lvl = (addr >> 8) & 0x3;
    if (this->reg.PRIV < req_priv_lvl) // not having required privileges
        throw illegal_instruction_fault(this->fault_data);
    auto it = csr_rd_cb.find(addr);
    if (it == csr_rd_cb.end() || !it->second) // non existent register
        throw illegal_instruction_fault(this->fault_data);
    return (this->*(it->second))(addr, val);
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_csr(unsigned addr, reg_t val) {
    if (addr >= csr.size()) return iss::Err;
    auto req_priv_lvl = (addr >> 8) & 0x3;
    if (this->reg.PRIV < req_priv_lvl) // not having required privileges
        throw illegal_instruction_fault(this->fault_data);
    if((addr&0xc00)==0xc00) // writing to read-only region
        throw illegal_instruction_fault(this->fault_data);
    auto it = csr_wr_cb.find(addr);
    if (it == csr_wr_cb.end() || !it->second) // non existent register
        throw illegal_instruction_fault(this->fault_data);
    return (this->*(it->second))(addr, val);
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_reg(unsigned addr, reg_t &val) {
    val = csr[addr];
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_null(unsigned addr, reg_t &val) {
    val = 0;
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_reg(unsigned addr, reg_t val) {
    csr[addr] = val;
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_cycle(unsigned addr, reg_t &val) {
    auto cycle_val = this->reg.icount + cycle_offset;
    if (addr == mcycle) {
        val = static_cast<reg_t>(cycle_val);
    } else if (addr == mcycleh) {
        if (sizeof(typename traits<BASE>::reg_t) != 4) return iss::Err;
        val = static_cast<reg_t>(cycle_val >> 32);
    }
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_cycle(unsigned addr, reg_t val) {
    if (sizeof(typename traits<BASE>::reg_t) != 4) {
        if (addr == mcycleh)
            return iss::Err;
        mcycle_csr = static_cast<uint64_t>(val);
    } else {
        if (addr == mcycle) {
            mcycle_csr = (mcycle_csr & 0xffffffff00000000) + val;
        } else  {
            mcycle_csr = (static_cast<uint64_t>(val)<<32) + (mcycle_csr & 0xffffffff);
        }
    }
    cycle_offset = mcycle_csr-this->reg.icount; // TODO: relying on wrap-around
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_instret(unsigned addr, reg_t &val) {
    if (addr == minstret) {
        val = static_cast<reg_t>(this->reg.instret);
    } else if (addr == minstreth) {
        if (sizeof(typename traits<BASE>::reg_t) != 4) return iss::Err;
        val = static_cast<reg_t>(this->reg.instret >> 32);
    }
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_instret(unsigned addr, reg_t val) {
    if (sizeof(typename traits<BASE>::reg_t) != 4) {
        if (addr == minstreth)
            return iss::Err;
        this->reg.instret = static_cast<uint64_t>(val);
    } else {
        if (addr == minstret) {
            this->reg.instret = (this->reg.instret & 0xffffffff00000000) + val;
        } else  {
            this->reg.instret = (static_cast<uint64_t>(val)<<32) + (this->reg.instret & 0xffffffff);
        }
    }
    this->reg.instret--;
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_time(unsigned addr, reg_t &val) {
    uint64_t time_val = this->reg.icount / (100000000 / 32768 - 1); //-> ~3052;
    if (addr == time) {
        val = static_cast<reg_t>(time_val);
    } else if (addr == timeh) {
        if (sizeof(typename traits<BASE>::reg_t) != 4) return iss::Err;
        val = static_cast<reg_t>(time_val >> 32);
    }
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_mtvec(unsigned addr, reg_t &val) {
    val = csr[mtvec] & ~2;
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_status(unsigned addr, reg_t &val) {
    val = state.mstatus & hart_state_type::get_mask();
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_status(unsigned addr, reg_t val) {
    state.write_mstatus(val);
    check_interrupt();
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_ie(unsigned addr, reg_t &val) {
    val = csr[mie];
    val &= csr[mideleg];
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_hartid(unsigned addr, reg_t &val) {
    val = mhartid_reg;
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_ie(unsigned addr, reg_t val) {
    auto mask = get_irq_mask();
    csr[mie] = (csr[mie] & ~mask) | (val & mask);
    check_interrupt();
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::read_ip(unsigned addr, reg_t &val) {
    val = csr[mip];
    val &= csr[mideleg];
    return iss::Ok;
}

template <typename BASE> iss::status riscv_hart_m_p<BASE>::write_ip(unsigned addr, reg_t val) {
    auto mask = get_irq_mask();
    mask &= ~(1 << 7); // MTIP is read only
    csr[mip] = (csr[mip] & ~mask) | (val & mask);
    check_interrupt();
    return iss::Ok;
}

template <typename BASE>
iss::status riscv_hart_m_p<BASE>::read_mem(phys_addr_t paddr, unsigned length, uint8_t *const data) {
    if(mem_read_cb) return mem_read_cb(paddr, length, data);
    switch (paddr.val) {
    case 0x0200BFF8: { // CLINT base, mtime reg
        if (sizeof(reg_t) < length) return iss::Err;
        reg_t time_val;
        this->read_csr(time, time_val);
        std::copy((uint8_t *)&time_val, ((uint8_t *)&time_val) + length, data);
    } break;
    case 0x10008000: {
        const mem_type::page_type &p = mem(paddr.val / mem.page_size);
        uint64_t offs = paddr.val & mem.page_addr_mask;
        std::copy(p.data() + offs, p.data() + offs + length, data);
        if (this->reg.icount > 30000) data[3] |= 0x80;
    } break;
    default: {
        for(auto offs=0U; offs<length; ++offs) {
            *(data + offs)=mem[(paddr.val+offs)%mem.size()];
        }
    }
    }
    return iss::Ok;
}

template <typename BASE>
iss::status riscv_hart_m_p<BASE>::write_mem(phys_addr_t paddr, unsigned length, const uint8_t *const data) {
    if ((paddr.val + length) > mem.size()) return iss::Err;
    if(mem_write_cb) return mem_write_cb(paddr, length, data);
    switch (paddr.val) {
    case 0x10013000: // UART0 base, TXFIFO reg
    case 0x10023000: // UART1 base, TXFIFO reg
        uart_buf << (char)data[0];
        if (((char)data[0]) == '\n' || data[0] == 0) {
            // LOG(INFO)<<"UART"<<((paddr.val>>16)&0x3)<<" send
            // '"<<uart_buf.str()<<"'";
            std::cout << uart_buf.str();
            uart_buf.str("");
        }
        break;
    case 0x10008000: { // HFROSC base, hfrosccfg reg
        mem_type::page_type &p = mem(paddr.val / mem.page_size);
        size_t offs = paddr.val & mem.page_addr_mask;
        std::copy(data, data + length, p.data() + offs);
        uint8_t &x = *(p.data() + offs + 3);
        if (x & 0x40) x |= 0x80; // hfroscrdy = 1 if hfroscen==1
    } break;
    case 0x10008008: { // HFROSC base, pllcfg reg
        mem_type::page_type &p = mem(paddr.val / mem.page_size);
        size_t offs = paddr.val & mem.page_addr_mask;
        std::copy(data, data + length, p.data() + offs);
        uint8_t &x = *(p.data() + offs + 3);
        x |= 0x80; // set pll lock upon writing
    } break;
    default: {
        mem_type::page_type &p = mem(paddr.val / mem.page_size);
        std::copy(data, data + length, p.data() + (paddr.val & mem.page_addr_mask));
        // tohost handling in case of riscv-test
        if (paddr.access && iss::access_type::FUNC) {
            auto tohost_upper = (traits<BASE>::XLEN == 32 && paddr.val == (tohost + 4));
            auto tohost_lower =
                (traits<BASE>::XLEN == 32 && paddr.val == tohost);
            if (tohost_lower || tohost_upper) {
                uint64_t hostvar = *reinterpret_cast<uint64_t *>(p.data() + (tohost & mem.page_addr_mask));
                if (tohost_upper || (tohost_lower && to_host_wr_cnt > 0)) {
                    switch (hostvar >> 48) {
                    case 0:
                        if (hostvar != 0x1) {
                            LOG(FATAL) << "tohost value is 0x" << std::hex << hostvar << std::dec << " (" << hostvar
                                       << "), stopping simulation";
                        } else {
                            LOG(INFO) << "tohost value is 0x" << std::hex << hostvar << std::dec << " (" << hostvar
                                      << "), stopping simulation";
                        }
                        this->reg.trap_state=std::numeric_limits<uint32_t>::max();
                        this->interrupt_sim=hostvar;
                        break;
                        //throw(iss::simulation_stopped(hostvar));
                    case 0x0101: {
                        char c = static_cast<char>(hostvar & 0xff);
                        if (c == '\n' || c == 0) {
                            LOG(INFO) << "tohost send '" << uart_buf.str() << "'";
                            uart_buf.str("");
                        } else
                            uart_buf << c;
                        to_host_wr_cnt = 0;
                    } break;
                    default:
                        break;
                    }
                } else if (tohost_lower)
                    to_host_wr_cnt++;
            } else if (traits<BASE>::XLEN == 32 && paddr.val == fromhost + 4) {
                uint64_t fhostvar = *reinterpret_cast<uint64_t *>(p.data() + (fromhost & mem.page_addr_mask));
                *reinterpret_cast<uint64_t *>(p.data() + (tohost & mem.page_addr_mask)) = fhostvar;
            }
        }
    }
    }
    return iss::Ok;
}

template <typename BASE> inline void riscv_hart_m_p<BASE>::reset(uint64_t address) {
    BASE::reset(address);
    state.mstatus = hart_state_type::mstatus_reset_val;
}

template <typename BASE> void riscv_hart_m_p<BASE>::check_interrupt() {
    auto ideleg = csr[mideleg];
    // Multiple simultaneous interrupts and traps at the same privilege level are
    // handled in the following decreasing priority order:
    // external interrupts, software interrupts, timer interrupts, then finally
    // any synchronous traps.
    auto ena_irq = csr[mip] & csr[mie];

    bool mie = state.mstatus.MIE;
    auto m_enabled = this->reg.PRIV < PRIV_M || (this->reg.PRIV == PRIV_M && mie);
    auto enabled_interrupts = m_enabled ? ena_irq & ~ideleg : 0;

    if (enabled_interrupts != 0) {
        int res = 0;
        while ((enabled_interrupts & 1) == 0) {
        	enabled_interrupts >>= 1;
        	res++;
        }
        this->reg.pending_trap = res << 16 | 1; // 0x80 << 24 | (cause << 16) | trap_id
    }
}

template <typename BASE> uint64_t riscv_hart_m_p<BASE>::enter_trap(uint64_t flags, uint64_t addr, uint64_t instr) {
    // flags are ACTIVE[31:31], CAUSE[30:16], TRAPID[15:0]
    // calculate and write mcause val
    auto trap_id = bit_sub<0, 16>(flags);
    auto cause = bit_sub<16, 15>(flags);
    if (trap_id == 0 && cause == 11) cause = 0x8 + PRIV_M; // adjust environment call cause
    // calculate effective privilege level
    if (trap_id == 0) { // exception
        // store ret addr in xepc register
        csr[mepc] = static_cast<reg_t>(addr); // store actual address instruction of exception
        csr[mtval] = cause==2?instr:fault_data;
        fault_data = 0;
    } else {
        csr[mepc] = this->reg.NEXT_PC; // store next address if interrupt
        this->reg.pending_trap = 0;
    }
    csr[mcause] = (trap_id << 31) + cause;
    // update mstatus
    // xPP field of mstatus is written with the active privilege mode at the time
    // of the trap; the x PIE field of mstatus
    // is written with the value of the active interrupt-enable bit at the time of
    // the trap; and the x IE field of mstatus
    // is cleared
    // store the actual privilege level in yPP and store interrupt enable flags
    state.mstatus.MPP = PRIV_M;
    state.mstatus.MPIE = state.mstatus.MIE;
    state.mstatus.MIE = false;

    // get trap vector
    auto ivec = csr[mtvec];
    // calculate addr// set NEXT_PC to trap addressess to jump to based on MODE
    // bits in mtvec
    this->reg.NEXT_PC = ivec & ~0x3UL;
    if ((ivec & 0x1) == 1 && trap_id != 0) this->reg.NEXT_PC += 4 * cause;
    // reset trap state
    this->reg.PRIV = PRIV_M;
    this->reg.trap_state = 0;
    std::array<char, 32> buffer;
    sprintf(buffer.data(), "0x%016lx", addr);
    if((flags&0xffffffff) != 0xffffffff)
    CLOG(INFO, disass) << (trap_id ? "Interrupt" : "Trap") << " with cause '"
                       << (trap_id ? irq_str[cause] : trap_str[cause]) << "' (" << cause << ")"
                       << " at address " << buffer.data() << " occurred";
    return this->reg.NEXT_PC;
}

template <typename BASE> uint64_t riscv_hart_m_p<BASE>::leave_trap(uint64_t flags) {
    state.mstatus.MIE = state.mstatus.MPIE;
    // sets the pc to the value stored in the x epc register.
    this->reg.NEXT_PC = csr[mepc];
    CLOG(INFO, disass) << "Executing xRET";
    return this->reg.NEXT_PC;
}

} // namespace arch
} // namespace iss

#endif /* _RISCV_HART_M_P_H */