BitStack.cs

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namespace System.Xml;
 
internal sealed class BitStack
{
    private uint[] _bitStack;
 
    private int _stackPos;
 
    private uint _curr;
 
    public BitStack()
    {
        _curr = 1u;
    }
 
    public void PushBit(bool bit)
    {
        if ((_curr & 0x80000000u) != 0)
        {
            PushCurr();
        }
        _curr = (_curr << 1) | (bit ? 1u : 0u);
    }
 
    public bool PopBit()
    {
        bool result = (_curr & 1) != 0;
        _curr >>= 1;
        if (_curr == 1)
        {
            PopCurr();
        }
        return result;
    }
 
    public bool PeekBit()
    {
        return (_curr & 1) != 0;
    }
 
    private void PushCurr()
    {
        if (_bitStack == null)
        {
            _bitStack = new uint[16];
        }
        _bitStack[_stackPos++] = _curr;
        _curr = 1u;
        int num = _bitStack.Length;
        if (_stackPos >= num)
        {
            uint[] array = new uint[2 * num];
            Array.Copy(_bitStack, array, num);
            _bitStack = array;
        }
    }
 
    private void PopCurr()
    {
        if (_stackPos > 0)
        {
            _curr = _bitStack[--_stackPos];
        }
    }
}