Refactor `.ips` patch applier
`RomGame` is never initialised with a non-null `patch` so this was and is unused
This commit is contained in:
YoshiRulz
parent
c2297283f4
commit
eb13e46f45
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@ -1,75 +0,0 @@
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using System;
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using System.IO;
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namespace BizHawk.Client.Common
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{
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public static class IPS
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{
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public static byte[] Patch(byte[] rom, Stream patch)
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{
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var ipsHeader = new byte[5];
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patch.Read(ipsHeader, 0, 5);
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const string header = "PATCH";
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for (int i = 0; i < 5; i++)
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{
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if (ipsHeader[i] != header[i])
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{
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Console.WriteLine("Patch file specified is invalid.");
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return null;
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}
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}
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// header verified, loop over patch entries
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const uint eof = ('E' * 0x10000) + ('O' * 0x100) + 'F';
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var ret = new MemoryStream(rom.Length);
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ret.Write(rom, 0, rom.Length);
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while (true)
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{
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uint offset = Read24(patch);
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if (offset == eof)
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{
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return ret.ToArray();
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}
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ushort size = Read16(patch);
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ret.Seek(offset, SeekOrigin.Begin);
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if (size != 0) // non-RLE patch
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{
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var patchData = new byte[size];
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patch.Read(patchData, 0, size);
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ret.Write(patchData, 0, patchData.Length);
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}
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else // RLE patch
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{
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size = Read16(patch);
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byte value = (byte)patch.ReadByte();
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for (int i = 0; i < size; i++)
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{
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ret.WriteByte(value);
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}
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}
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}
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}
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private static ushort Read16(Stream patch)
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{
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int upper = patch.ReadByte();
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int lower = patch.ReadByte();
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return (ushort)((upper * 0x100) + lower);
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}
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private static uint Read24(Stream patch)
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{
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int upper = patch.ReadByte();
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int middle = patch.ReadByte();
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int lower = patch.ReadByte();
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return (uint)((upper * 0x10000) + (middle * 0x100) + lower);
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}
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}
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}
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@ -2,6 +2,7 @@
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using System.Globalization;
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using BizHawk.Common;
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using BizHawk.Common.IOExtensions;
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using BizHawk.Common.NumberExtensions;
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using BizHawk.Emulation.Common;
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@ -110,14 +111,18 @@ namespace BizHawk.Client.Common
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CheckForPatchOptions();
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if (patch != null)
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if (patch is null) return;
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using var patchFile = new HawkFile(patch);
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patchFile.BindFirstOf(".ips");
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if (!patchFile.IsBound) return;
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var patchBytes = patchFile.GetStream().ReadAllBytes();
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if (BPSPatcher.IsIPSFile(patchBytes))
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{
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using var patchFile = new HawkFile(patch);
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patchFile.BindFirstOf(".ips");
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if (patchFile.IsBound)
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{
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RomData = IPS.Patch(RomData, patchFile.GetStream());
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}
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RomData = BPSPatcher.Patch(RomData, new BPSPatcher.IPSPayload(patchBytes));
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}
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else
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{
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throw new Exception("doesn't appear to be a BPS or IPS patch");
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}
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}
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@ -0,0 +1,137 @@
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Text;
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namespace BizHawk.Common
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{
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public static class BPSPatcher
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{
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/// <remarks>
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/// constructor assumes valid header/footer<br/>
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/// https://zerosoft.zophar.net/ips.php
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/// </remarks>
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/// <seealso cref="IsIPSFile"/>
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public ref struct IPSPayload
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{
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internal static readonly byte[] FOOTER = Encoding.ASCII.GetBytes("EOF");
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internal static readonly byte[] HEADER = Encoding.ASCII.GetBytes("PATCH");
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internal static void CheckRomSize(ReadOnlySpan<byte> rom)
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{
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const int MAX_BASE_ROM_LENGTH = 0x1000000; // linked spec says 0xFFFFFF bits [sic] but that makes no sense
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if (MAX_BASE_ROM_LENGTH < rom.Length)
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{
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#if true // it can patch the start of the file just fine, no need to throw here
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Console.WriteLine("warning: IPS uses 24-bit offsets, so it can only index the first 0x1000000 octets of this rom");
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#else
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throw new ArgumentException(message: "IPS can't patch files this big", paramName: nameof(rom));
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#endif
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}
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}
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private static IReadOnlyList<(int PatchOffset, int TargetOffset, int Size, bool IsRLE)> ParseRecords(ReadOnlySpan<byte> data)
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{
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List<(int PatchOffset, int TargetOffset, int Size, bool IsRLE)> records = new();
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try
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{
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var i = 0;
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while (i != data.Length)
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{
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var targetOffset = (data[i++] * 0x10000) | (data[i++] * 0x100) | data[i++];
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var size = (data[i++] * 0x100) | data[i++];
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if (size is 0)
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{
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var rleSize = (data[i++] * 0x100) | data[i++];
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Debug.Assert(rleSize is not 0);
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records.Add((i, targetOffset, rleSize, true));
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i++;
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}
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else
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{
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records.Add((i, targetOffset, size, false));
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i += size;
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}
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}
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}
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catch (ArgumentOutOfRangeException e)
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{
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throw new Exception("unexpected EOF in IPS patch", e);
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}
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records.Sort((a, b) => (a.TargetOffset + a.Size).CompareTo(b.TargetOffset + b.Size));
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return records;
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}
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private readonly ReadOnlySpan<byte> _data;
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private readonly bool _isValid;
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private IReadOnlyList<(int PatchOffset, int TargetOffset, int Size, bool IsRLE)>? _records;
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internal IReadOnlyList<(int PatchOffset, int TargetOffset, int Size, bool IsRLE)> Records
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=> _isValid ? (_records ??= ParseRecords(_data)) : throw new InvalidOperationException(ERR_MSG_UNINIT);
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/// <remarks>assumes valid header/footer</remarks>
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/// <seealso cref="IsIPSFile"/>
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public IPSPayload(ReadOnlySpan<byte> dataWithHeader)
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{
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_data = dataWithHeader.Slice(start: 5, length: dataWithHeader.Length - 8);
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_isValid = true;
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_records = null;
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}
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internal void DoPatch(Span<byte> rom)
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{
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foreach (var (patchOffset, targetOffset, size, isRLE) in Records)
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{
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if (isRLE)
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{
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var value = _data[patchOffset];
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for (int j = targetOffset, endExclusive = j + size; j < endExclusive; j++) rom[j] = value;
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}
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else
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{
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for (var j = 0; j < size; j++) rom[targetOffset + j] = _data[patchOffset + j];
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}
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}
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}
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}
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private const string ERR_MSG_UNINIT = "uninitialised struct";
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public static bool IsIPSFile(ReadOnlySpan<byte> dataWithHeader)
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{
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const int MIN_VALID_IPS_SIZE = 8;
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return MIN_VALID_IPS_SIZE <= dataWithHeader.Length
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&& dataWithHeader.Slice(start: 0, length: 5).SequenceEqual(IPSPayload.HEADER)
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&& dataWithHeader.Slice(start: dataWithHeader.Length - 3, length: 3).SequenceEqual(IPSPayload.FOOTER);
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}
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/// <remarks>may patch in place, returning <paramref name="baseRom"/>, or allocate a new array</remarks>
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public static byte[] Patch(byte[] baseRom, IPSPayload patch)
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{
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var rom = baseRom;
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var last = patch.Records[patch.Records.Count - 1];
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var reqSize = last.TargetOffset + last.Size;
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if (baseRom.Length < reqSize)
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{
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rom = new byte[reqSize];
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Array.Copy(sourceArray: baseRom, destinationArray: rom, length: baseRom.Length);
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}
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IPSPayload.CheckRomSize(rom);
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patch.DoPatch(rom);
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return rom;
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}
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/// <remarks>is this even useful?</remarks>
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public static bool TryPatchInPlace(Span<byte> rom, IPSPayload patch)
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{
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IPSPayload.CheckRomSize(rom);
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var last = patch.Records[patch.Records.Count - 1];
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if (rom.Length < last.TargetOffset + last.Size) return false;
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patch.DoPatch(rom);
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return true;
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}
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}
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}
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