HashHelpers.cs

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using System.Runtime.CompilerServices;
using System.Runtime.Serialization;
using System.Threading;
 
namespace System.Collections;
 
internal static class HashHelpers
{
    private static readonly int[] s_primes = new int[72]
    {
        3, 7, 11, 17, 23, 29, 37, 47, 59, 71,
        89, 107, 131, 163, 197, 239, 293, 353, 431, 521,
        631, 761, 919, 1103, 1327, 1597, 1931, 2333, 2801, 3371,
        4049, 4861, 5839, 7013, 8419, 10103, 12143, 14591, 17519, 21023,
        25229, 30293, 36353, 43627, 52361, 62851, 75431, 90523, 108631, 130363,
        156437, 187751, 225307, 270371, 324449, 389357, 467237, 560689, 672827, 807403,
        968897, 1162687, 1395263, 1674319, 2009191, 2411033, 2893249, 3471899, 4166287, 4999559,
        5999471, 7199369
    };
 
    private static ConditionalWeakTable<object, SerializationInfo> s_serializationInfoTable;
 
    public static ConditionalWeakTable<object, SerializationInfo> SerializationInfoTable
    {
        get
        {
            if (s_serializationInfoTable == null)
            {
                Interlocked.CompareExchange(ref s_serializationInfoTable, new ConditionalWeakTable<object, SerializationInfo>(), null);
            }
            return s_serializationInfoTable;
        }
    }
 
    public static bool IsPrime(int candidate)
    {
        if (((uint)candidate & (true ? 1u : 0u)) != 0)
        {
            int num = (int)Math.Sqrt(candidate);
            for (int i = 3; i <= num; i += 2)
            {
                if (candidate % i == 0)
                {
                    return false;
                }
            }
            return true;
        }
        return candidate == 2;
    }
 
    public static int GetPrime(int min)
    {
        if (min < 0)
        {
            throw new ArgumentException(SR.Arg_HTCapacityOverflow);
        }
        int[] array = s_primes;
        foreach (int num in array)
        {
            if (num >= min)
            {
                return num;
            }
        }
        for (int j = min | 1; j < int.MaxValue; j += 2)
        {
            if (IsPrime(j) && (j - 1) % 101 != 0)
            {
                return j;
            }
        }
        return min;
    }
 
    public static int ExpandPrime(int oldSize)
    {
        int num = 2 * oldSize;
        if ((uint)num > 2147483587u && 2147483587 > oldSize)
        {
            return 2147483587;
        }
        return GetPrime(num);
    }
 
    public static ulong GetFastModMultiplier(uint divisor)
    {
        return ulong.MaxValue / (ulong)divisor + 1;
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static uint FastMod(uint value, uint divisor, ulong multiplier)
    {
        return (uint)(((multiplier * value >> 32) + 1) * divisor >> 32);
    }
}