//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="Sqrt"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using System;
using System.Runtime.CompilerServices;

namespace StgSharp.Mathematics
{
    public static partial class Scalar
    {

        public static unsafe float SeedSqrt(float x)
        {
            ArgumentOutOfRangeException.ThrowIfNegative(x);
            if (x <= 1e-12) {
                return 0;
            }
            uint a = *(uint*)&x;
            uint f = a;
            f >>= 23;
            f /= 2;
            f += 64;
            a -= 0b_0011_1111_0000_0000_0000_0000_0000_0000;
            uint e = a << 8;
            e >>= 8;
            e *= 0b_1101_0001;
            e >>= 24;
            e += 0b_0000_0000_0001_0000_1010_1000_1110_0010;
            f <<= 23;
            e += f;
            float result = *(float*)&e;
            result = (result + (x / result)) / 2;
            return (result + (x / result)) / 2;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static float Sqrt(float x)
        {
            return MathF.Sqrt(x);
            /**/
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static double Sqrt(double x)
        {
            return System.Math.Sqrt(x);
        }

    }
}