2
0
Fork 0
mirror of https://github.com/kwsch/PKHeX synced 2024-12-24 03:13:18 +00:00
PKHeX/PKHeX.Core/Legality/BinLinkerAccessor.cs
2022-05-07 11:47:01 -07:00

52 lines
1.8 KiB
C#

using System;
using System.Diagnostics;
using static System.Buffers.Binary.BinaryPrimitives;
namespace PKHeX.Core;
/// <summary>
/// Unpacks a BinLinkerAccessor generated file container into individual arrays.
/// </summary>
[DebuggerDisplay($"{{{nameof(Identifier)},nq}}[{{{nameof(Length)},nq}}]")]
public readonly ref struct BinLinkerAccessor
{
/// <summary> Backing data object </summary>
private readonly ReadOnlySpan<byte> Data;
/// <summary> Total count of files available for accessing. </summary>
public int Length => ReadUInt16LittleEndian(Data[2..]);
/// <summary> Magic identifier for the file. </summary>
public string Identifier => new(new[] {(char)Data[0], (char)Data[1]});
/// <summary>
/// Retrieves a view of the entry at the requested <see cref="index"/>.
/// </summary>
/// <param name="index">Entry to retrieve.</param>
public ReadOnlySpan<byte> this[int index] => GetEntry(index);
private BinLinkerAccessor(ReadOnlySpan<byte> data) => Data = data;
private ReadOnlySpan<byte> GetEntry(int index)
{
int offset = 4 + (index * sizeof(int));
int end = ReadInt32LittleEndian(Data[(offset + 4)..]);
int start = ReadInt32LittleEndian(Data[offset..]);
return Data[start..end];
}
/// <summary>
/// Sanity checks the input <see cref="data"/> only in DEBUG builds, and returns a new wrapper.
/// </summary>
/// <param name="data">Data reference</param>
/// <param name="identifier">Expected identifier (debug verification only)</param>
public static BinLinkerAccessor Get(ReadOnlySpan<byte> data, string identifier)
{
var result = new BinLinkerAccessor(data);
#if DEBUG
Debug.Assert(data.Length > 4);
Debug.Assert(identifier[0] == data[0] && identifier[1] == data[1]);
#endif
return result;
}
}