//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="HLSFAllocator.Level.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 
// 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.Collections.Generic;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.HighPerformance.Memory
{
    public unsafe partial class HybridLayerSegregatedFitAllocator
    {

        private const int MaxLevel = 9;

        private static readonly int[] levelSize = [
            64, 256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216
            ];

        public int AlignOfLevel(int bucketLevel)
        {
            int blockSize = levelSize[bucketLevel];
            return int.Min(blockSize, _align);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private int GetLevelFromSize(uint size)
        {
            // Ensure minimum size
            if (size <= 64)
            {
                return 0;
            }

            /*
            * size = 64 * 4 ^ level
            * level = Log4(size/64)
            * level = Log4(size) - Log4(64)
            * level = Log4(size) - 3
            * Log4 is the same as count of >>=2 or /= 4;
            */
            int level = -3;
            while (size > 0)
            {
                level++;
                size >>= 2;
            }
            return level;

            // Find the position of the highest set bit (equivalent to floor(log2(size)))
            int msb = 31 - System.Numerics.BitOperations.LeadingZeroCount(size);

            // Convert MSB position to level index using bit manipulation
            // MSB: 6->0, 7->0, 8->1, 9->1, 10->2, 11->2, 12->3, 13->3, etc.
            // Pattern: level = max(0, (msb - 6) >> 1)
            int level = Math.Max(0, (msb - 6) >> 1);


            // Clamp to valid range
            return Math.Min(level, levelSize.Length - 1);
        }

    }

    public enum CommonMemoryAlign : int
    {

        XMMLevel = 16,
        YMMLevel = 32,
        ZMMLevel = 64,

        ArmNEONLevel = 16,

    }
}