stgsharp/StgSharp.Common/Mathematics/Linear/Matrix.cs

//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="Matrix.cs"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person 
// obtaining a copy of this software and associated documentation 
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// and to permit persons to whom the Software is furnished to do so, 
// subject to the following conditions:
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// The above copyright notice and 
// this permission notice shall be included in all copies 
// or substantial portions of the Software.
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using StgSharp.HighPerformance;
using System;
using System.Numerics;
using System.Runtime.CompilerServices;
using hlsfAllocator = global::StgSharp.HighPerformance.Memory.HybridLayerSegregatedFitAllocator;

// using hlsfHandle = global::StgSharp.HighPerformance.Memory.HybridLayerSegregatedFitAllocationHandle;

namespace StgSharp.Mathematics
{
    public abstract unsafe partial class Matrix<T> where T: unmanaged, INumber<T>
    {

        private protected readonly int t_count = 16 / sizeof(T);

        private protected readonly int t_size = sizeof(T);

        private protected Matrix() { }

        public abstract ref T this[int column, int row]
        {
            get;
        }

        public abstract unsafe Matrix<T> this[ReadOnlySpan<MatrixIndex> column, ReadOnlySpan<MatrixIndex> row]
        {
            get;
            set;
        }

        public static hlsfAllocator? DefaultAllocator
        {
            get
            {
                ArgumentNullException.ThrowIfNull(field, nameof(DefaultAllocator));
                return null;
            }
            set;
        } = null;

        /// <summary>
        ///   Length of the matrix in columns.
        /// </summary>
        public int ColumnLength { get; init; }

        /// <summary>
        ///   Length of the matrix in rows.
        /// </summary>
        public int RowLength { get; init; }

        public static MatrixAllocation DefaultAllocation { get; set; } = MatrixAllocation.GC;

        internal abstract MatrixKernel<T>* Buffer { get; }

        protected internal int KernelColumnLength { get; init; }

        protected internal int KernelRowLength { get; init; }

        public static Matrix<T> FromDefault(int columnLength, int rowLength)
        {
            return DefaultAllocation switch
            {
                MatrixAllocation.GC => FromGC(columnLength, rowLength),
                MatrixAllocation.HLSF => FromHlsf(columnLength, rowLength, DefaultAllocator!),
                _ => throw new NotSupportedException("This allocation is not supported."),
            };
        }

        public static Matrix<T> FromGC(int columnLength, int rowLength)
        {
            return new GCMatrix<T>(columnLength, rowLength);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Matrix<T> FromHlsf(int columnLength, int rowLength, hlsfAllocator allocator)
        {
            return new HlsfMatrix<T>(columnLength, rowLength, allocator);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public abstract MatrixSegmentEnumeration<T> GetColumnEnumeration();

        public abstract ref MatrixKernel<T> GetMatrixKernel(int column, int row);

        public abstract MatrixSegmentEnumeration<T> GetRowEnumeration();

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public abstract MatrixSegmentEnumeration<T> GetSequentialEnumeration();

        [Obsolete("This method does not contain boarder check, so be careful on size or use indexer instead.", false)]
        public abstract ref T UnsafeIndex(int column, int row);

        private protected void AssertIndex(int column, int row)
        {
            if (column < 0 || column >= ColumnLength) {
                throw new ArgumentOutOfRangeException(nameof(column));
            }

            if (row < 0 || row >= RowLength) {
                throw new ArgumentOutOfRangeException(nameof(row));
            }
        }

    }

    public readonly unsafe ref struct MatrixSegmentEnumeration<T>(
                                      MatrixKernel<T>* source,
                                      int stride,
                                      int size,
                                      int secondaryStride,
                                      int secondarySize)
        where T: unmanaged, INumber<T>
    {

        private readonly MatrixKernel<T>* _source = source;
        private readonly int _secondarySize = secondarySize;
        private readonly int _secondaryStride = secondaryStride;

        private readonly int _size = size;
        private readonly int _stride = stride;

        public Enumerator<T> GetEnumerator()
        {
            return new Enumerator<T>(in this);
        }

        public ref struct Enumerator<T>(in MatrixSegmentEnumeration<T> enumeration) where T: unmanaged, INumber<T>
        {

            private MatrixKernel<T>* _current = enumeration._source - enumeration._stride;
            private readonly MatrixKernel<T>* _end = enumeration._source + enumeration._size;
            private readonly int _secondarySize = enumeration._secondarySize;
            private readonly int _secondaryStride = enumeration._secondaryStride;
            private readonly int _stride = enumeration._stride;

            public readonly MatrixSegment<T> Current
            {
                [MethodImpl(MethodImplOptions.AggressiveInlining)]
                get => new(_current, _secondarySize, _secondaryStride);
            }

            public bool MoveNext()
            {
                _current += _stride;
                return _current < _end;
            }

        }

    }

    public readonly unsafe ref struct MatrixSegment<T>(MatrixKernel<T>* source, int size, int stride)
        where T: unmanaged, INumber<T>
    {

        private readonly MatrixKernel<T>* _source = source;
        private readonly int _size = size;
        private readonly int _stride = stride;

        public ref MatrixKernel<T> this[int index]
        {
            get
            {
                if (index < 0 || index >= _size) {
                    throw new ArgumentOutOfRangeException(nameof(index));
                }
                return ref _source[index * _stride];
            }
        }

        public Enumerator<T> GetEnumerator()
        {
            return new Enumerator<T>(_source, _size, _stride);
        }

        public ref struct Enumerator<T>(MatrixKernel<T>* source, int count, int stride) where T: unmanaged, INumber<T>
        {

            private readonly MatrixKernel<T>* _end = source + (count * stride);
            private readonly int _stride = stride;

            public MatrixKernel<T>* Current
            {
                [MethodImpl(MethodImplOptions.AggressiveInlining)]
                get;
                [MethodImpl(MethodImplOptions.AggressiveInlining)]
                private set;
            } = source - stride;

            public bool MoveNext()
            {
                Current += _stride;
                return Current < _end;
            }

        }

    }
}