/*******************************************************************************
 * Copyright (C) 2020 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 <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/tcc/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 tcc {
namespace ${coreDef.name.toLowerCase()} {
using namespace iss::arch;
using namespace iss::debugger;

template <typename ARCH> class vm_impl : public iss::tcc::vm_base<ARCH> {
public:
    using super       = typename iss::tcc::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 tu_builder  = typename super::tu_builder;

    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 (vm_base<ARCH>::tgt_adapter == nullptr)
            vm_base<ARCH>::tgt_adapter = new riscv_target_adapter<ARCH>(srv, this->get_arch());
        return vm_base<ARCH>::tgt_adapter;
    }

protected:
    using vm_base<ARCH>::get_reg_ptr;

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

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

    void setup_module(std::string m) override {
        super::setup_module(m);
    }

    compile_ret_t gen_single_inst_behavior(virt_addr_t &, unsigned int &, tu_builder&) override;

    void gen_trap_behavior(tu_builder& tu) override;

    void gen_raise_trap(tu_builder& tu, uint16_t trap_id, uint16_t cause);

    void gen_leave_trap(tu_builder& tu, unsigned lvl);

    void gen_wait(tu_builder& tu, unsigned type);

    inline void gen_trap_check(tu_builder& tu) {
        tu("if(*trap_state!=0) goto trap_entry;");
    }

    inline void gen_set_pc(tu_builder& tu, virt_addr_t pc, unsigned reg_num) {
        switch(reg_num){
        case traits<ARCH>::NEXT_PC:
            tu("*next_pc = {:#x};", pc.val);
            break;
        case traits<ARCH>::PC:
            tu("*pc = {:#x};", pc.val);
            break;
        default:
            if(!tu.defined_regs[reg_num]){
                tu("reg_t* reg{:02d} = (reg_t*){:#x};", reg_num, reinterpret_cast<uintptr_t>(get_reg_ptr(reg_num)));
            tu.defined_regs[reg_num]=true;
            }
            tu("*reg{:02d} = {:#x};", reg_num, pc.val);
        }
    }

    // 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;

    std::array<compile_func *, 4> qlut;

    std::array<const uint32_t, 4> lutmasks = {{EXTR_MASK16, EXTR_MASK16, EXTR_MASK16, EXTR_MASK32}};

    void expand_bit_mask(int pos, uint32_t mask, uint32_t value, uint32_t valid, uint32_t idx, compile_func lut[],
                         compile_func f) {
        if (pos < 0) {
            lut[idx] = f;
        } else {
            auto bitmask = 1UL << pos;
            if ((mask & bitmask) == 0) {
                expand_bit_mask(pos - 1, mask, value, valid, idx, lut, f);
            } else {
                if ((valid & bitmask) == 0) {
                    expand_bit_mask(pos - 1, mask, value, valid, (idx << 1), lut, f);
                    expand_bit_mask(pos - 1, mask, value, valid, (idx << 1) + 1, lut, f);
                } else {
                    auto new_val = idx << 1;
                    if ((value & bitmask) != 0) new_val++;
                    expand_bit_mask(pos - 1, mask, value, valid, new_val, lut, f);
                }
            }
        }
    }

    inline uint32_t extract_fields(uint32_t val) { return extract_fields(29, val >> 2, lutmasks[val & 0x3], 0); }

    uint32_t extract_fields(int pos, uint32_t val, uint32_t mask, uint32_t lut_val) {
        if (pos >= 0) {
            auto bitmask = 1UL << pos;
            if ((mask & bitmask) == 0) {
                lut_val = extract_fields(pos - 1, val, mask, lut_val);
            } else {
                auto new_val = lut_val << 1;
                if ((val & bitmask) != 0) new_val++;
                lut_val = extract_fields(pos - 1, val, mask, new_val);
            }
        }
        return lut_val;
    }

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 ${instr.instruction.name}, encoding '${instr.encoding}' */
        {${instr.length}, 0b${instr.value}, 0b${instr.mask}, &this_class::__${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, tu_builder& tu){<%instr.code.eachLine{%>
        ${it}<%}%>
    }
    <%}%>
    /****************************************************************************
     * end opcode definitions
     ****************************************************************************/
    compile_ret_t illegal_intruction(virt_addr_t &pc, code_word_t instr, tu_builder& tu) {
        vm_impl::gen_sync(tu, iss::PRE_SYNC, instr_descr.size());
        pc = pc + ((instr & 3) == 3 ? 4 : 2);
        gen_raise_trap(tu, 0, 2);     // illegal instruction trap
        vm_impl::gen_sync(tu, iss::POST_SYNC, instr_descr.size());
        vm_impl::gen_trap_check(tu);
        return BRANCH;
    }
};

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()); }

template <typename ARCH>
vm_impl<ARCH>::vm_impl(ARCH &core, unsigned core_id, unsigned cluster_id)
: vm_base<ARCH>(core, core_id, cluster_id) {
    qlut[0] = lut_00.data();
    qlut[1] = lut_01.data();
    qlut[2] = lut_10.data();
    qlut[3] = lut_11.data();
    for (auto instr : instr_descr) {
        auto quantrant = instr.value & 0x3;
        expand_bit_mask(29, lutmasks[quantrant], instr.value >> 2, instr.mask >> 2, 0, qlut[quantrant], instr.op);
    }
}

template <typename ARCH>
std::tuple<continuation_e>
vm_impl<ARCH>::gen_single_inst_behavior(virt_addr_t &pc, unsigned int &inst_cnt, tu_builder& tu) {
    // we fetch at max 4 byte, alignment is 2
    enum {TRAP_ID=1<<16};
    code_word_t insn = 0;
    const typename traits<ARCH>::addr_t upper_bits = ~traits<ARCH>::PGMASK;
    phys_addr_t paddr(pc);
    auto *const data = (uint8_t *)&insn;
    paddr = this->core.v2p(pc);
    if ((pc.val & upper_bits) != ((pc.val + 2) & upper_bits)) { // we may cross a page boundary
        auto res = this->core.read(paddr, 2, data);
        if (res != iss::Ok) throw trap_access(TRAP_ID, pc.val);
        if ((insn & 0x3) == 0x3) { // this is a 32bit instruction
            res = this->core.read(this->core.v2p(pc + 2), 2, data + 2);
        }
    } else {
        auto res = this->core.read(paddr, 4, data);
        if (res != iss::Ok) throw trap_access(TRAP_ID, pc.val);
    }
    if (insn == 0x0000006f || (insn&0xffff)==0xa001) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
    // curr pc on stack
    ++inst_cnt;
    auto lut_val = extract_fields(insn);
    auto f = qlut[insn & 0x3][lut_val];
    if (f == nullptr) {
        f = &this_class::illegal_intruction;
    }
    return (this->*f)(pc, insn, tu);
}

template <typename ARCH> void vm_impl<ARCH>::gen_raise_trap(tu_builder& tu, uint16_t trap_id, uint16_t cause) {
    tu("  *trap_state = {:#x};", 0x80 << 24 | (cause << 16) | trap_id);
    tu.store(tu.constant(std::numeric_limits<uint32_t>::max(), 32),traits<ARCH>::LAST_BRANCH);
}

template <typename ARCH> void vm_impl<ARCH>::gen_leave_trap(tu_builder& tu, unsigned lvl) {
    tu("leave_trap(core_ptr, {});", lvl);
    tu.store(tu.read_mem(traits<ARCH>::CSR, (lvl << 8) + 0x41, traits<ARCH>::XLEN),traits<ARCH>::NEXT_PC);
    tu.store(tu.constant(std::numeric_limits<uint32_t>::max(), 32),traits<ARCH>::LAST_BRANCH);
}

template <typename ARCH> void vm_impl<ARCH>::gen_wait(tu_builder& tu, unsigned type) {
}

template <typename ARCH> void vm_impl<ARCH>::gen_trap_behavior(tu_builder& tu) {
    tu("trap_entry:");
    tu("enter_trap(core_ptr, *trap_state, *pc);");
    tu.store(tu.constant(std::numeric_limits<uint32_t>::max(),32),traits<ARCH>::LAST_BRANCH);
    tu("return *next_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 iss