극저온 방사광 X-선 나노회절 기반 준1차원 전하밀도파(Quasi-1D CDW, NbSe3) 집단 슬라이딩 솔리톤 능동 서보 아키텍처 (.NET 9 C# SIMD)

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

namespace ZeliDesk.Quantum.LowDimensionalPhysics
{
    /// <summary>
    /// 준1차원 전하밀도파(NbSe3) 집단 슬라이딩 솔리톤 및 샤피로 스텝 서보
    /// GC 무할당 ref struct 및 AVX-256 SIMD 가속화
    /// </summary>
    public ref struct Quasi1dCdwSlidingServo
    {
        private readonly ReadOnlySpan<float> _appliedFields;      // 인가 전계 E (V/cm)
        private readonly ReadOnlySpan<float> _measuredCurrents;   // 측정 전류밀도 j (A/cm^2)
        private readonly Span<float> _cdwCurrents;                // 연산된 순수 CDW 슬라이딩 전류
        private readonly Span<float> _washboardFrequencies;       // 워시보드 샤피로 RF 주파수 (MHz)

        private readonly float _thresholdField;  // 임계 피닝 전계 Eth (V/cm)
        private readonly float _normalOhmicCond; // 정상 옴 전도도 sigma_N
        private readonly float _washboardFactor; // MHz / (A/cm^2)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Quasi1dCdwSlidingServo(
            ReadOnlySpan<float> appliedFields,
            ReadOnlySpan<float> measuredCurrents,
            Span<float> cdwCurrents,
            Span<float> washboardFrequencies,
            float thresholdField = 0.12f,
            float normalOhmicCond = 1450.0f,
            float washboardFactor = 4.85f)
        {
            _appliedFields = appliedFields;
            _measuredCurrents = measuredCurrents;
            _cdwCurrents = cdwCurrents;
            _washboardFrequencies = washboardFrequencies;
            _thresholdField = thresholdField;
            _normalOhmicCond = normalOhmicCond;
            _washboardFactor = washboardFactor;
        }

        /// <summary>
        /// 8채널 나노사슬의 슬라이딩 전도를 SIMD 병렬 분석하여 고유 워시보드 주파수 산출
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
        public void ProcessSlidingCdwLoop()
        {
            int length = _appliedFields.Length;
            int simdLength = length - (length % 8);

            Vector256<float> vEth = Vector256.Create(_thresholdField);
            Vector256<float> vSigmaN = Vector256.Create(_normalOhmicCond * 0.001f); // 스케일링
            Vector256<float> vWfactor = Vector256.Create(_washboardFactor);
            Vector256<float> vZero = Vector256<float>.Zero;

            int i = 0;
            if (Avx2.IsSupported)
            {
                for (; i < simdLength; i += 8)
                {
                    Vector256<float> vE = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_appliedFields.Slice(i, 8))[0]);
                    Vector256<float> vJtot = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_measuredCurrents.Slice(i, 8))[0]);

                    // 정상 옴 전류: J_norm = sigma_N * E
                    Vector256<float> vJnorm = Avx.Multiply(vSigmaN, vE);

                    // 순수 CDW 전류: J_cdw = max(0, J_tot - J_norm) (단, E > Eth 일 때만)
                    Vector256<float> vJdiff = Avx.Subtract(vJtot, vJnorm);
                    Vector256<float> vAboveEth = Avx.CompareGreaterThan(vE, vEth);
                    Vector256<float> vJcdw = Avx.And(Avx.Max(vZero, vJdiff), vAboveEth);

                    // 워시보드 주파수 f_w = Factor * J_cdw
                    Vector256<float> vFreq = Avx.Multiply(vWfactor, vJcdw);

                    vJcdw.CopyTo(_cdwCurrents.Slice(i, 8));
                    vFreq.CopyTo(_washboardFrequencies.Slice(i, 8));
                }
            }

            for (; i < length; i++)
            {
                float jnorm = (_normalOhmicCond * 0.001f) * _appliedFields[i];
                float jcdw = 0.0f;
                if (_appliedFields[i] > _thresholdField)
                {
                    jcdw = MathF.Max(0.0f, _measuredCurrents[i] - jnorm);
                }
                _cdwCurrents[i] = jcdw;
                _washboardFrequencies[i] = _washboardFactor * jcdw;
            }
        }
    }
}