// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

namespace System.Numerics.System.Numerics
{
    internal static class VectorMath
    {
        public static Vector128<float> Lerp(Vector128<float> a, Vector128<float> b, Vector128<float> t)
        {
            if (Fma.IsSupported)
            {
                return Fma.MultiplyAdd(Sse.Subtract(b, a), t, a);
            }
            else if (Sse.IsSupported)
            {
                return Sse.Add(a, Sse.Multiply(Sse.Subtract(b, a), t));
            }
            else
            {
                throw new NotSupportedException();
            }
        }

        public static bool Equal(Vector128<float> vector1, Vector128<float> vector2)
        {
            if (Sse.IsSupported)
            {
                return Sse.MoveMask(Sse.CompareNotEqual(vector1, vector2)) == 0;
            }
            else
            {
                throw new NotSupportedException();
            }
        }

        public static unsafe float HorizontalSum(Vector128<float> vector)
        {
            if (Sse3.IsSupported)
            {
                var ha = Sse3.HorizontalAdd(vector, vector);
                ha = Sse3.HorizontalAdd(ha, ha);
                return Sse.ConvertToSingle(ha);
            }
            else if (Sse.IsSupported)
            {
                float* values = stackalloc float[4];
                Sse.Store(values, vector);
                return values[0] + values[1] + values[2] + values[4];
            }
            else
            {
                throw new NotSupportedException();
            }
        }
    }
}