Ryujinx/Ryujinx.Audio.Renderer/Utils/BitArray.cs
2021-01-01 00:12:32 +01:00

120 lines
4 KiB
C#

//
// Copyright (c) 2019-2021 Ryujinx
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
using System;
using System.Runtime.CompilerServices;
namespace Ryujinx.Audio.Renderer.Utils
{
/// <summary>
/// A simple bit array implementation backed by a <see cref="Memory{T}"/>.
/// </summary>
public class BitArray
{
/// <summary>
/// The backing storage of the <see cref="BitArray"/>.
/// </summary>
private Memory<byte> _storage;
/// <summary>
/// Create a new <see cref="BitArray"/> from <see cref="Memory{T}"/>.
/// </summary>
/// <param name="storage">The backing storage of the <see cref="BitArray"/>.</param>
public BitArray(Memory<byte> storage)
{
_storage = storage;
}
/// <summary>
/// Get the byte position of a given bit index.
/// </summary>
/// <param name="index">A bit index.</param>
/// <returns>The byte position of a given bit index.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int ToPosition(int index) => index / 8;
/// <summary>
/// Get the bit position of a given bit index inside a byte.
/// </summary>
/// <param name="index">A bit index.</param>
/// <returns>The bit position of a given bit index inside a byte.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int ToBitPosition(int index) => index % 8;
/// <summary>
/// Test if the bit at the given index is set.
/// </summary>
/// <param name="index">A bit index.</param>
/// <returns>Return true if the bit at the given index is set</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public bool Test(int index)
{
ulong mask = 1ul << ToBitPosition(index);
return (_storage.Span[ToPosition(index)] & mask) == mask;
}
/// <summary>
/// Set the bit at the given index.
/// </summary>
/// <param name="index">A bit index.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Set(int index)
{
Set(index, true);
}
/// <summary>
/// Reset the bit at the given index.
/// </summary>
/// <param name="index">A bit index.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Reset(int index)
{
Set(index, false);
}
/// <summary>
/// Set a bit value at the given index.
/// </summary>
/// <param name="index">A bit index.</param>
/// <param name="value">The new bit value.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private void Set(int index, bool value)
{
byte mask = (byte)(1 << ToBitPosition(index));
if (value)
{
_storage.Span[ToPosition(index)] |= mask;
}
else
{
_storage.Span[ToPosition(index)] &= (byte)~mask;
}
}
/// <summary>
/// Reset all bits in the storage.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Reset()
{
_storage.Span.Fill(0);
}
}
}