xmrig/src/workers/CpuThread.cpp

/* XMRig
 * Copyright 2010      Jeff Garzik <jgarzik@pobox.com>
 * Copyright 2012-2014 pooler      <pooler@litecoinpool.org>
 * Copyright 2014      Lucas Jones <https://github.com/lucasjones>
 * Copyright 2014-2016 Wolf9466    <https://github.com/OhGodAPet>
 * Copyright 2016      Jay D Dee   <jayddee246@gmail.com>
 * Copyright 2017-2018 XMR-Stak    <https://github.com/fireice-uk>, <https://github.com/psychocrypt>
 * Copyright 2016-2018 XMRig       <https://github.com/xmrig>, <support@xmrig.com>
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <assert.h>


#include "common/cpu/Cpu.h"
#include "common/log/Log.h"
#include "common/net/Pool.h"
#include "crypto/Asm.h"
#include "rapidjson/document.h"
#include "workers/CpuThread.h"


#if defined(XMRIG_ARM)
#   include "crypto/CryptoNight_arm.h"
#else
#   include "crypto/CryptoNight_x86.h"
#endif


xmrig::CpuThread::CpuThread(size_t index, Algo algorithm, AlgoVariant av, Multiway multiway, int64_t affinity, int priority, bool softAES, bool prefetch, Assembly assembly) :
    m_algorithm(algorithm),
    m_av(av),
    m_assembly(assembly),
    m_prefetch(prefetch),
    m_softAES(softAES),
    m_priority(priority),
    m_affinity(affinity),
    m_multiway(multiway),
    m_index(index)
{
}


bool xmrig::CpuThread::isSoftAES(AlgoVariant av)
{
    return av == AV_SINGLE_SOFT || av == AV_DOUBLE_SOFT || av > AV_PENTA;
}


xmrig::CpuThread::cn_hash_fun xmrig::CpuThread::fn(Algo algorithm, AlgoVariant av, Variant variant, Assembly assembly)
{
    assert(variant >= VARIANT_0 && variant < VARIANT_MAX);

#   ifndef XMRIG_NO_ASM
    constexpr const size_t count = VARIANT_MAX * 10 * 3 + 2;
#   else
    constexpr const size_t count = VARIANT_MAX * 10 * 3;
#   endif

    static const cn_hash_fun func_table[count] = {
        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_0>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_0>,

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_1>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_1>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_1>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_1>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_1>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_1>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_1>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_1>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_1>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_1>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_TUBE

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_XTL>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_XTL>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_XTL>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_XTL>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_XTL>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_XTL>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_XTL>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_XTL>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_XTL>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_XTL>,

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_MSR>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_MSR>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_MSR>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_MSR>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_MSR>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_MSR>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_MSR>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_MSR>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_MSR>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_MSR>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XHV

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_XAO>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_XAO>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_XAO>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_XAO>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_XAO>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_XAO>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_XAO>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_XAO>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_XAO>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_XAO>,

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_RTO>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_RTO>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_RTO>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_RTO>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_RTO>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_RTO>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_RTO>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_RTO>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_RTO>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_RTO>,

        cryptonight_single_hash<CRYPTONIGHT, false, VARIANT_2>,
        cryptonight_double_hash<CRYPTONIGHT, false, VARIANT_2>,
        cryptonight_single_hash<CRYPTONIGHT, true,  VARIANT_2>,
        cryptonight_double_hash<CRYPTONIGHT, true,  VARIANT_2>,
        cryptonight_triple_hash<CRYPTONIGHT, false, VARIANT_2>,
        cryptonight_quad_hash<CRYPTONIGHT,   false, VARIANT_2>,
        cryptonight_penta_hash<CRYPTONIGHT,  false, VARIANT_2>,
        cryptonight_triple_hash<CRYPTONIGHT, true,  VARIANT_2>,
        cryptonight_quad_hash<CRYPTONIGHT,   true,  VARIANT_2>,
        cryptonight_penta_hash<CRYPTONIGHT,  true,  VARIANT_2>,

#       ifndef XMRIG_NO_AEON
        cryptonight_single_hash<CRYPTONIGHT_LITE, false, VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT_LITE, false, VARIANT_0>,
        cryptonight_single_hash<CRYPTONIGHT_LITE, true,  VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT_LITE, true,  VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT_LITE, false, VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT_LITE,   false, VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT_LITE,  false, VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT_LITE, true,  VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT_LITE,   true,  VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT_LITE,  true,  VARIANT_0>,

        cryptonight_single_hash<CRYPTONIGHT_LITE, false, VARIANT_1>,
        cryptonight_double_hash<CRYPTONIGHT_LITE, false, VARIANT_1>,
        cryptonight_single_hash<CRYPTONIGHT_LITE, true,  VARIANT_1>,
        cryptonight_double_hash<CRYPTONIGHT_LITE, true,  VARIANT_1>,
        cryptonight_triple_hash<CRYPTONIGHT_LITE, false, VARIANT_1>,
        cryptonight_quad_hash<CRYPTONIGHT_LITE,   false, VARIANT_1>,
        cryptonight_penta_hash<CRYPTONIGHT_LITE,  false, VARIANT_1>,
        cryptonight_triple_hash<CRYPTONIGHT_LITE, true,  VARIANT_1>,
        cryptonight_quad_hash<CRYPTONIGHT_LITE,   true,  VARIANT_1>,
        cryptonight_penta_hash<CRYPTONIGHT_LITE,  true,  VARIANT_1>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_TUBE
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XTL
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_MSR
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XHV
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XAO
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_RTO
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_2
#       else
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
#       endif

#       ifndef XMRIG_NO_SUMO
        cryptonight_single_hash<CRYPTONIGHT_HEAVY, false, VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, false, VARIANT_0>,
        cryptonight_single_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_0>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, false, VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   false, VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  false, VARIANT_0>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_0>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   true,  VARIANT_0>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  true,  VARIANT_0>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_1

        cryptonight_single_hash<CRYPTONIGHT_HEAVY, false, VARIANT_TUBE>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, false, VARIANT_TUBE>,
        cryptonight_single_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_TUBE>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_TUBE>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, false, VARIANT_TUBE>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   false, VARIANT_TUBE>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  false, VARIANT_TUBE>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_TUBE>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   true,  VARIANT_TUBE>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  true,  VARIANT_TUBE>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XTL
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_MSR

        cryptonight_single_hash<CRYPTONIGHT_HEAVY, false, VARIANT_XHV>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, false, VARIANT_XHV>,
        cryptonight_single_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_XHV>,
        cryptonight_double_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_XHV>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, false, VARIANT_XHV>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   false, VARIANT_XHV>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  false, VARIANT_XHV>,
        cryptonight_triple_hash<CRYPTONIGHT_HEAVY, true,  VARIANT_XHV>,
        cryptonight_quad_hash<CRYPTONIGHT_HEAVY,   true,  VARIANT_XHV>,
        cryptonight_penta_hash<CRYPTONIGHT_HEAVY,  true,  VARIANT_XHV>,

        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_XAO
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_RTO
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, // VARIANT_2
#       else
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
#       endif
#       ifndef XMRIG_NO_ASM
        cryptonight_single_hash_asm<CRYPTONIGHT, VARIANT_2, ASM_INTEL>,
        cryptonight_single_hash_asm<CRYPTONIGHT, VARIANT_2, ASM_RYZEN>
#       endif
    };

#   ifndef NDEBUG
    const size_t index = fnIndex(algorithm, av, variant, assembly);
    cn_hash_fun func = func_table[index];

    assert(index < sizeof(func_table) / sizeof(func_table[0]));
    assert(func != nullptr);

    return func;
#   else
    return func_table[fnIndex(algorithm, av, variant, assembly)];
#   endif
}


xmrig::CpuThread *xmrig::CpuThread::createFromAV(size_t index, Algo algorithm, AlgoVariant av, int64_t affinity, int priority, Assembly assembly)
{
    assert(av > AV_AUTO && av < AV_MAX);

    int64_t cpuId = -1L;

    if (affinity != -1L) {
        size_t idx = 0;

        for (size_t i = 0; i < 64; i++) {
            if (!(affinity & (1ULL << i))) {
                continue;
            }

            if (idx == index) {
                cpuId = i;
                break;
            }

            idx++;
        }
    }

    return new CpuThread(index, algorithm, av, multiway(av), cpuId, priority, isSoftAES(av), false, assembly);
}


xmrig::CpuThread *xmrig::CpuThread::createFromData(size_t index, Algo algorithm, const CpuThread::Data &data, int priority, bool softAES)
{
    int av                  = AV_AUTO;
    const Multiway multiway = data.multiway;

    if (multiway <= DoubleWay) {
        av = softAES ? (multiway + 2) : multiway;
    }
    else {
        av = softAES ? (multiway + 5) : (multiway + 2);
    }

    assert(av > AV_AUTO && av < AV_MAX);

    return new CpuThread(index, algorithm, static_cast<AlgoVariant>(av), multiway, data.affinity, priority, softAES, false, data.assembly);
}


xmrig::CpuThread::Data xmrig::CpuThread::parse(const rapidjson::Value &object)
{
    Data data;

    const auto &multiway = object["low_power_mode"];
    if (multiway.IsBool()) {
        data.multiway = multiway.IsTrue() ? DoubleWay : SingleWay;
        data.valid    = true;
    }
    else if (multiway.IsUint()) {
        data.setMultiway(multiway.GetInt());
    }

    if (!data.valid) {
        return data;
    }

    const auto &affinity = object["affine_to_cpu"];
    if (affinity.IsUint64()) {
        data.affinity = affinity.GetInt64();
    }

#   ifndef XMRIG_NO_ASM
    data.assembly = Asm::parse(object["asm"]);
#   endif

    return data;
}


xmrig::IThread::Multiway xmrig::CpuThread::multiway(AlgoVariant av)
{
    switch (av) {
    case AV_SINGLE:
    case AV_SINGLE_SOFT:
        return SingleWay;

    case AV_DOUBLE_SOFT:
    case AV_DOUBLE:
        return DoubleWay;

    case AV_TRIPLE_SOFT:
    case AV_TRIPLE:
        return TripleWay;

    case AV_QUAD_SOFT:
    case AV_QUAD:
        return QuadWay;

    case AV_PENTA_SOFT:
    case AV_PENTA:
        return PentaWay;

    default:
        break;
    }

    return SingleWay;
}


#ifdef APP_DEBUG
void xmrig::CpuThread::print() const
{
    LOG_DEBUG(GREEN_BOLD("CPU thread:   ") " index " WHITE_BOLD("%zu") ", multiway " WHITE_BOLD("%d") ", av " WHITE_BOLD("%d") ",",
              index(), static_cast<int>(multiway()), static_cast<int>(m_av));

#   ifndef XMRIG_NO_ASM
    LOG_DEBUG("               assembly: %s, affine_to_cpu: %" PRId64, Asm::toString(m_assembly), affinity());
#   else
    LOG_DEBUG("               affine_to_cpu: %" PRId64, affinity());
#   endif
}
#endif


#ifndef XMRIG_NO_API
rapidjson::Value xmrig::CpuThread::toAPI(rapidjson::Document &doc) const
{
    using namespace rapidjson;

    Value obj(kObjectType);
    auto &allocator = doc.GetAllocator();

    obj.AddMember("type",          "cpu", allocator);
    obj.AddMember("av",             m_av, allocator);
    obj.AddMember("low_power_mode", multiway(), allocator);
    obj.AddMember("affine_to_cpu",  affinity(), allocator);
    obj.AddMember("priority",       priority(), allocator);
    obj.AddMember("soft_aes",       isSoftAES(), allocator);

    return obj;
}
#endif


rapidjson::Value xmrig::CpuThread::toConfig(rapidjson::Document &doc) const
{
    using namespace rapidjson;

    Value obj(kObjectType);
    auto &allocator = doc.GetAllocator();

    obj.AddMember("low_power_mode", multiway(), allocator);
    obj.AddMember("affine_to_cpu",  affinity() == -1L ? Value(kFalseType) : Value(affinity()), allocator);

#   ifndef XMRIG_NO_ASM
    obj.AddMember("asm", Asm::toJSON(m_assembly), allocator);
#   endif

    return obj;
}


size_t xmrig::CpuThread::fnIndex(Algo algorithm, AlgoVariant av, Variant variant, Assembly assembly)
{
    const size_t index = VARIANT_MAX * 10 * algorithm + 10 * variant + av - 1;

#   ifndef XMRIG_NO_ASM
    if (assembly == ASM_AUTO) {
        assembly = Cpu::info()->assembly();
    }

    if (assembly == ASM_NONE) {
        return index;
    }

    constexpr const size_t offset = VARIANT_MAX * 10 * 3;

    if (algorithm == CRYPTONIGHT && variant == VARIANT_2) {
        if (av == AV_SINGLE) {
            return offset + assembly - 2;
        }
    }
#   endif

    return index;
}