/*******************************************************************************
 * 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.
 *
 *******************************************************************************/

#include "../fp_functions.h"
#include <iss/arch/${coreDef.name.toLowerCase()}.h>
#include <iss/arch/riscv_hart_m_p.h>
#include <iss/debugger/gdb_session.h>
#include <iss/debugger/server.h>
#include <iss/iss.h>
#include <iss/interp/vm_base.h>
#include <util/logging.h>
#include <sstream>

#ifndef FMT_HEADER_ONLY
#define FMT_HEADER_ONLY
#endif
#include <fmt/format.h>

#include <array>
#include <iss/debugger/riscv_target_adapter.h>

namespace iss {
namespace interp {
namespace ${coreDef.name.toLowerCase()} {
using namespace iss::arch;
using namespace iss::debugger;

template <typename ARCH> class vm_impl : public iss::interp::vm_base<ARCH> {
public:
    using traits = arch::traits<ARCH>;
    using super       = typename iss::interp::vm_base<ARCH>;
    using virt_addr_t = typename super::virt_addr_t;
    using phys_addr_t = typename super::phys_addr_t;
    using code_word_t = typename super::code_word_t;
    using addr_t      = typename super::addr_t;
    using reg_t       = typename traits::reg_t;
    using mem_type_e  = typename traits::mem_type_e;
    
    const bool has_compressed = traits::MISA_VAL & 0b100;
    
    vm_impl();

    vm_impl(ARCH &core, unsigned core_id = 0, unsigned cluster_id = 0);

    void enableDebug(bool enable) { super::sync_exec = super::ALL_SYNC; }

    target_adapter_if *accquire_target_adapter(server_if *srv) override {
        debugger_if::dbg_enabled = true;
        if (super::tgt_adapter == nullptr)
            super::tgt_adapter = new riscv_target_adapter<ARCH>(srv, this->get_arch());
        return super::tgt_adapter;
    }

protected:
    using this_class = vm_impl<ARCH>;
    using compile_ret_t = virt_addr_t;
    using compile_func = compile_ret_t (this_class::*)(virt_addr_t &pc, code_word_t instr);

    inline const char *name(size_t index){return traits::reg_aliases.at(index);}

    compile_func decode_inst(code_word_t instr) ;
    virt_addr_t execute_inst(finish_cond_e cond, virt_addr_t start, uint64_t icount_limit) override;

    // some compile time constants
    // enum { MASK16 = 0b1111110001100011, MASK32 = 0b11111111111100000111000001111111 };
    enum { MASK16 = 0b1111111111111111, MASK32 = 0b11111111111100000111000001111111 };
    enum { EXTR_MASK16 = MASK16 >> 2, EXTR_MASK32 = MASK32 >> 2 };
    enum { LUT_SIZE = 1 << util::bit_count(EXTR_MASK32), LUT_SIZE_C = 1 << util::bit_count(EXTR_MASK16) };

    std::array<compile_func, LUT_SIZE> lut;

    std::array<compile_func, LUT_SIZE_C> lut_00, lut_01, lut_10;
    std::array<compile_func, LUT_SIZE> lut_11;

    struct instruction_pattern {
        uint32_t value;
        uint32_t mask;
        compile_func opc;
    };

    std::array<std::vector<instruction_pattern>, 4> qlut;

    inline void raise(uint16_t trap_id, uint16_t cause){
        auto trap_val =  0x80ULL << 24 | (cause << 16) | trap_id;
        this->template get_reg<uint32_t>(traits::TRAP_STATE) = trap_val;
        this->template get_reg<uint32_t>(traits::NEXT_PC) = std::numeric_limits<uint32_t>::max();
    }

    inline void leave(unsigned lvl){
        this->core.leave_trap(lvl);
    }

    inline void wait(unsigned type){
        this->core.wait_until(type);
    }

    template<typename T>
    T& pc_assign(T& val){super::ex_info.branch_taken=true; return val;}
    inline uint8_t readSpace1(typename super::mem_type_e space, uint64_t addr){
        auto ret = super::template read_mem<uint8_t>(space, addr);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
        return ret;
    }
    inline uint16_t readSpace2(typename super::mem_type_e space, uint64_t addr){
        auto ret = super::template read_mem<uint16_t>(space, addr);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
        return ret;
    }
    inline uint32_t readSpace4(typename super::mem_type_e space, uint64_t addr){
        auto ret = super::template read_mem<uint32_t>(space, addr);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
        return ret;
    }
    inline uint64_t readSpace8(typename super::mem_type_e space, uint64_t addr){
        auto ret = super::template read_mem<uint64_t>(space, addr);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
        return ret;
    }
    inline void writeSpace1(typename super::mem_type_e space, uint64_t addr, uint8_t data){
        super::write_mem(space, addr, data);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
    }
    inline void writeSpace2(typename super::mem_type_e space, uint64_t addr, uint16_t data){
        super::write_mem(space, addr, data);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
    }
    inline void writeSpace4(typename super::mem_type_e space, uint64_t addr, uint32_t data){
        super::write_mem(space, addr, data);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
    }
    inline void writeSpace8(typename super::mem_type_e space, uint64_t addr, uint64_t data){
        super::write_mem(space, addr, data);
        if(this->template get_reg<uint32_t>(traits::TRAP_STATE)) throw 0;
    }
    template<unsigned W, typename U, typename S = typename std::make_signed<U>::type>
    inline S sext(U from) {
        auto mask = (1ULL<<W) - 1;
        auto sign_mask = 1ULL<<(W-1);
        return (from & mask) | ((from & sign_mask) ? ~mask : 0);
    }

private:
    /****************************************************************************
     * start opcode definitions
     ****************************************************************************/
    struct InstructionDesriptor {
        size_t length;
        uint32_t value;
        uint32_t mask;
        compile_func op;
    };

    const std::array<InstructionDesriptor, ${instructions.size}> instr_descr = {{
         /* entries are: size, valid value, valid mask, function ptr */<%instructions.each{instr -> %>
        /* instruction ${instr.instruction.name} */
        {${instr.length}, ${instr.encoding}, ${instr.mask}, &this_class::__${generator.functionName(instr.name)}},<%}%>
    }};
 
    /* instruction definitions */<%instructions.eachWithIndex{instr, idx -> %>
    /* instruction ${idx}: ${instr.name} */
    compile_ret_t __${generator.functionName(instr.name)}(virt_addr_t& pc, code_word_t instr){
        // pre execution stuff
        auto* PC = reinterpret_cast<uint${addrDataWidth}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::PC]);
        auto NEXT_PC = reinterpret_cast<uint${addrDataWidth}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::NEXT_PC]);
        *PC=*NEXT_PC;
        auto* trap_state = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::TRAP_STATE]);
        *trap_state = *reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::PENDING_TRAP]);
        if(this->sync_exec && PRE_SYNC) this->do_sync(PRE_SYNC, ${idx});
        <%instr.fields.eachLine{%>${it}
        <%}%>if(this->disass_enabled){
            /* generate console output when executing the command */
            <%instr.disass.eachLine{%>${it}
            <%}%>
        }
        // used registers<%instr.usedVariables.each{ k,v->
            if(v.isArray) {%>
        auto* ${k} = reinterpret_cast<uint${v.type.size}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::${k}0]);<% }else{ %> 
        auto* ${k} = reinterpret_cast<uint${v.type.size}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::${k}]);
        <%}}%>// calculate next pc value
        *NEXT_PC = *PC + ${instr.length/8};
        // execute instruction
        try {
        <%instr.behavior.eachLine{%>${it}
        <%}%>} catch(...){}
        // post execution stuff
        if(!has_compressed && (*NEXT_PC&0x3)!=0) raise(0,  0);
        if(this->sync_exec && POST_SYNC) this->do_sync(POST_SYNC, ${idx});
        // trap check
        if(*trap_state!=0){
            super::core.enter_trap(*trap_state, pc.val, instr);
        } else {
            (*reinterpret_cast<uint64_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::ICOUNT]))++;
            (*reinterpret_cast<uint64_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::INSTRET]))++;
        }
        (*reinterpret_cast<uint64_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::CYCLE]))++;
        pc.val=*NEXT_PC;
        return pc;
    }
    <%}%>
    /****************************************************************************
     * end opcode definitions
     ****************************************************************************/
    compile_ret_t illegal_intruction(virt_addr_t &pc, code_word_t instr) {
        this->do_sync(PRE_SYNC, static_cast<unsigned>(arch::traits<ARCH>::opcode_e::MAX_OPCODE));
        uint32_t* PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::PC]);
        uint32_t* NEXT_PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::NEXT_PC]);
        *NEXT_PC = *PC + ((instr & 3) == 3 ? 4 : 2);
        raise(0,  2);
        // post execution stuff
        if(this->sync_exec && POST_SYNC) this->do_sync(POST_SYNC, static_cast<unsigned>(arch::traits<ARCH>::opcode_e::MAX_OPCODE));
        auto* trap_state = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::TRAP_STATE]);
        // trap check
        if(*trap_state!=0){
            super::core.enter_trap(*trap_state, pc.val, instr);
        }
        pc.val=*NEXT_PC;
        return pc;
    }

    static constexpr typename traits::addr_t upper_bits = ~traits::PGMASK;
    iss::status fetch_ins(virt_addr_t pc, uint8_t * data){
        auto phys_pc = this->core.v2p(pc);
        //if ((pc.val & upper_bits) != ((pc.val + 2) & upper_bits)) { // we may cross a page boundary
        //    if (this->core.read(phys_pc, 2, data) != iss::Ok) return iss::Err;
        //    if ((data[0] & 0x3) == 0x3) // this is a 32bit instruction
        //        if (this->core.read(this->core.v2p(pc + 2), 2, data + 2) != iss::Ok) return iss::Err;
        //} else {
            if (this->core.read(phys_pc, 4, data) != iss::Ok)  return iss::Err;
        //}
        return iss::Ok;
    }
};

template <typename CODE_WORD> void debug_fn(CODE_WORD insn) {
    volatile CODE_WORD x = insn;
    insn = 2 * x;
}

template <typename ARCH> vm_impl<ARCH>::vm_impl() { this(new ARCH()); }

// according to
// https://stackoverflow.com/questions/8871204/count-number-of-1s-in-binary-representation
#ifdef __GCC__
constexpr size_t bit_count(uint32_t u) { return __builtin_popcount(u); }
#elif __cplusplus < 201402L
constexpr size_t uCount(uint32_t u) { return u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111); }
constexpr size_t bit_count(uint32_t u) { return ((uCount(u) + (uCount(u) >> 3)) & 030707070707) % 63; }
#else
constexpr size_t bit_count(uint32_t u) {
    size_t uCount = u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111);
    return ((uCount + (uCount >> 3)) & 030707070707) % 63;
}
#endif

template <typename ARCH>
vm_impl<ARCH>::vm_impl(ARCH &core, unsigned core_id, unsigned cluster_id)
: vm_base<ARCH>(core, core_id, cluster_id) {
    for (auto instr : instr_descr) {
        auto quadrant = instr.value & 0x3;
        qlut[quadrant].push_back(instruction_pattern{instr.value, instr.mask, instr.op});
    }
    for(auto& lut: qlut){
        std::sort(std::begin(lut), std::end(lut), [](instruction_pattern const& a, instruction_pattern const& b){
            return bit_count(a.mask) > bit_count(b.mask);
        });
    }
}

inline bool is_count_limit_enabled(finish_cond_e cond){
    return (cond & finish_cond_e::COUNT_LIMIT) == finish_cond_e::COUNT_LIMIT;
}

inline bool is_jump_to_self_enabled(finish_cond_e cond){
    return (cond & finish_cond_e::JUMP_TO_SELF) == finish_cond_e::JUMP_TO_SELF;
}

template <typename ARCH>
typename vm_impl<ARCH>::compile_func vm_impl<ARCH>::decode_inst(code_word_t instr){
    for(auto& e: qlut[instr&0x3]){
        if(!((instr&e.mask) ^ e.value )) return e.opc;
    }
    return &this_class::illegal_intruction;
}

template <typename ARCH>
typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e cond, virt_addr_t start, uint64_t icount_limit){
    // we fetch at max 4 byte, alignment is 2
    code_word_t insn = 0;
    auto *const data = (uint8_t *)&insn;
    auto pc=start;
    while(!this->core.should_stop() &&
            !(is_count_limit_enabled(cond) && this->core.get_icount() >= icount_limit)){
        auto res = fetch_ins(pc, data);
        if(res!=iss::Ok){
            this->do_sync(POST_SYNC, std::numeric_limits<unsigned>::max());
            pc.val = super::core.enter_trap(std::numeric_limits<uint64_t>::max(), pc.val, 0);
        } else {
            if (is_jump_to_self_enabled(cond) &&
                    (insn == 0x0000006f || (insn&0xffff)==0xa001)) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
            auto f = decode_inst(insn);
            auto old_pc = pc.val;
            pc = (this->*f)(pc, insn);
        }
    }
    return pc;
}

} // namespace mnrv32

template <>
std::unique_ptr<vm_if> create<arch::${coreDef.name.toLowerCase()}>(arch::${coreDef.name.toLowerCase()} *core, unsigned short port, bool dump) {
    auto ret = new ${coreDef.name.toLowerCase()}::vm_impl<arch::${coreDef.name.toLowerCase()}>(*core, dump);
    if (port != 0) debugger::server<debugger::gdb_session>::run_server(ret, port);
    return std::unique_ptr<vm_if>(ret);
}
} // namespace interp
} // namespace iss