극저온 방사광 X-선 나노회절 기반 호이슬러(Heusler, Ni-Mn-Ga) 강자성 형상기억합금 마르텐사이트 트윈 경계 이동 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.SmartMaterials
{
    /// <summary>
    /// 호이슬러(Ni2MnGa) 강자성 형상기억합금 트윈 경계 이동 능동 제어 서보
    /// GC 무할당 ref struct 및 AVX-256 SIMD 가속화
    /// </summary>
    public ref struct HeuslerFsmaTwinBoundaryServo
    {
        private readonly ReadOnlySpan<float> _peakIntensity1;    // 트윈 변체 1 회절 강도
        private readonly ReadOnlySpan<float> _peakIntensity2;    // 트윈 변체 2 회절 강도
        private readonly Span<float> _twinVolumeFractions;       // 연산된 트윈 분율 V_twin
        private readonly Span<float> _magneticFieldCommands;     // 구동 자기장 지령 (Tesla)

        private readonly float _targetFraction;  // 목표 트윈 체적 분율 (0.5f)
        private readonly float _fieldGain;       // 자기장 제어 게인 (T/unit)
        private readonly float _maxField;        // 최대 자장 한계 (1.5 T)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public HeuslerFsmaTwinBoundaryServo(
            ReadOnlySpan<float> peakIntensity1,
            ReadOnlySpan<float> peakIntensity2,
            Span<float> twinVolumeFractions,
            Span<float> magneticFieldCommands,
            float targetFraction = 0.5f,
            float fieldGain = 2.4f,
            float maxField = 1.5f)
        {
            _peakIntensity1 = peakIntensity1;
            _peakIntensity2 = peakIntensity2;
            _twinVolumeFractions = twinVolumeFractions;
            _magneticFieldCommands = magneticFieldCommands;
            _targetFraction = targetFraction;
            _fieldGain = fieldGain;
            _maxField = maxField;
        }

        /// <summary>
        /// 8채널 회절 피크 강도로부터 트윈 체적 분율 및 자장 지령을 SIMD 병렬 연산
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
        public void ExecuteTwinControlLoop()
        {
            int length = _peakIntensity1.Length;
            int simdLength = length - (length % 8);

            Vector256<float> vTgt = Vector256.Create(_targetFraction);
            Vector256<float> vGain = Vector256.Create(_fieldGain);
            Vector256<float> vMaxB = Vector256.Create(_maxField);
            Vector256<float> vMinB = Vector256.Create(-_maxField);
            Vector256<float> vEps = Vector256.Create(1e-4f);

            int i = 0;
            if (Avx2.IsSupported)
            {
                for (; i < simdLength; i += 8)
                {
                    Vector256<float> vI1 = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_peakIntensity1.Slice(i, 8))[0]);
                    Vector256<float> vI2 = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_peakIntensity2.Slice(i, 8))[0]);

                    // 분모: I1 + I2 + eps
                    Vector256<float> vSum = Avx.Add(Avx.Add(vI1, vI2), vEps);

                    // 트윈 분율: V_twin = I1 / (I1 + I2 + eps)
                    Vector256<float> vFrac = Avx.Divide(vI1, vSum);

                    // 편차: Err = Frac - Target
                    Vector256<float> vErr = Avx.Subtract(vFrac, vTgt);

                    // 자장 명령 = Gain * Err
                    Vector256<float> vBcmd = Avx.Multiply(vGain, vErr);
                    Vector256<float> vClampedB = Avx.Min(vMaxB, Avx.Max(vMinB, vBcmd));

                    vFrac.CopyTo(_twinVolumeFractions.Slice(i, 8));
                    vClampedB.CopyTo(_magneticFieldCommands.Slice(i, 8));
                }
            }

            for (; i < length; i++)
            {
                float sum = _peakIntensity1[i] + _peakIntensity2[i] + 1e-4f;
                float frac = _peakIntensity1[i] / sum;
                float err = frac - _targetFraction;
                float b = Math.Clamp(_fieldGain * err, -_maxField, _maxField);

                _twinVolumeFractions[i] = frac;
                _magneticFieldCommands[i] = b;
            }
        }
    }
}