극저온 방사광 X-선 나노회절 기반 교대자성체(Altermagnet, RuO2) 피에조 자기 스핀 분할 토크(SST) 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.Altermagnets
{
    /// <summary>
    /// 교대자성체(RuO2) 피에조 자기 스핀 분할 토크(SST) 능동 제어 서보
    /// GC 제로 할당 ref struct 및 AVX-256 SIMD 가속화
    /// </summary>
    public ref struct AltermagnetSpinSplittingServo
    {
        private readonly ReadOnlySpan<float> _shearStrains;      // 실측 전단 변형률 epsilon_xy
        private readonly ReadOnlySpan<float> _chargeCurrents;    // 인가 전하 전류 밀도 j_c (MA/cm^2)
        private readonly Span<float> _spinTorques;               // 산출된 스핀 분할 토크 T_sst
        private readonly Span<float> _piezoFeedbackVoltages;     // 피에조 능동 보정 전압 (V)

        private readonly float _sstEfficiency;   // SST 효율 계수 theta_SST
        private readonly float _targetStrain;    // 목표 전단 변형률
        private readonly float _piezoVoltageGain;// 피에조 게인 (V/strain)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public AltermagnetSpinSplittingServo(
            ReadOnlySpan<float> shearStrains,
            ReadOnlySpan<float> chargeCurrents,
            Span<float> spinTorques,
            Span<float> piezoFeedbackVoltages,
            float sstEfficiency = 0.38f,
            float targetStrain = 0.005f,
            float piezoVoltageGain = 120.0f)
        {
            _shearStrains = shearStrains;
            _chargeCurrents = chargeCurrents;
            _spinTorques = spinTorques;
            _piezoFeedbackVoltages = piezoFeedbackVoltages;
            _sstEfficiency = sstEfficiency;
            _targetStrain = targetStrain;
            _piezoVoltageGain = piezoVoltageGain;
        }

        /// <summary>
        /// 8채널의 전단 변형률 및 전하 전류를 SIMD로 병렬 분석하여 스핀 토크 및 피에조 피드백 도출
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
        public void ProcessSpinSplittingControl()
        {
            int length = _shearStrains.Length;
            int simdLength = length - (length % 8);

            Vector256<float> vTheta = Vector256.Create(_sstEfficiency);
            Vector256<float> vTargetStrain = Vector256.Create(_targetStrain);
            Vector256<float> vGain = Vector256.Create(_piezoVoltageGain);

            int i = 0;
            if (Avx2.IsSupported)
            {
                for (; i < simdLength; i += 8)
                {
                    Vector256<float> vStrain = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_shearStrains.Slice(i, 8))[0]);
                    Vector256<float> vJc = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_chargeCurrents.Slice(i, 8))[0]);

                    // 스핀 토크 T_sst = theta * Jc * strain
                    Vector256<float> vTorque = Avx.Multiply(vTheta, Avx.Multiply(vJc, vStrain));

                    // 변형률 오차: DeltaStrain = strain - targetStrain
                    Vector256<float> vDeltaStrain = Avx.Subtract(vStrain, vTargetStrain);

                    // 피에조 전압 = -Gain * DeltaStrain
                    Vector256<float> vPzt = Avx.Multiply(Avx.Subtract(Vector256<float>.Zero, vDeltaStrain), vGain);

                    vTorque.CopyTo(_spinTorques.Slice(i, 8));
                    vPzt.CopyTo(_piezoFeedbackVoltages.Slice(i, 8));
                }
            }

            for (; i < length; i++)
            {
                float torque = _sstEfficiency * _chargeCurrents[i] * _shearStrains[i];
                float deltaStrain = _shearStrains[i] - _targetStrain;
                _spinTorques[i] = torque;
                _piezoFeedbackVoltages[i] = -_piezoVoltageGain * deltaStrain;
            }
        }
    }
}