R/Ryujinx.HLE/Loaders/Mods/MemPatch.cs

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using Ryujinx.Common.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
namespace Ryujinx.HLE.Loaders.Mods
{
public class MemPatch
{
readonly Dictionary<uint, byte[]> _patches = new Dictionary<uint, byte[]>();
/// <summary>
/// Adds a patch to specified offset. Overwrites if already present.
/// </summary>
/// <param name="offset">Memory offset</param>
/// <param name="patch">The patch to add</param>
public void Add(uint offset, byte[] patch)
{
_patches[offset] = patch;
}
/// <summary>
/// Adds a patch in the form of an RLE (Fill mode).
/// </summary>
/// <param name="offset">Memory offset</param>
/// <param name="length"The fill length</param>
/// <param name="filler">The byte to fill</param>
public void AddFill(uint offset, int length, byte filler)
{
// TODO: Can be made space efficient by changing `_patches`
// Should suffice for now
byte[] patch = new byte[length];
patch.AsSpan().Fill(filler);
_patches[offset] = patch;
}
/// <summary>
/// Adds all patches from an existing MemPatch
/// </summary>
/// <param name="patches">The patches to add</param>
public void AddFrom(MemPatch patches)
{
if (patches == null)
{
return;
}
foreach (var (patchOffset, patch) in patches._patches)
{
_patches[patchOffset] = patch;
}
}
/// <summary>
/// Applies all the patches added to this instance.
/// </summary>
/// <remarks>
/// Patches are applied in ascending order of offsets to guarantee
/// overlapping patches always apply the same way.
/// </remarks>
/// <param name="memory">The span of bytes to patch</param>
/// <param name="maxSize">The maximum size of the slice of patchable memory</param>
/// <param name="protectedOffset">A secondary offset used in special cases (NSO header)</param>
/// <returns>Successful patches count</returns>
public int Patch(Span<byte> memory, int protectedOffset = 0)
{
int count = 0;
foreach (var (offset, patch) in _patches.OrderBy(item => item.Key))
{
int patchOffset = (int)offset;
int patchSize = patch.Length;
if (patchOffset < protectedOffset || patchOffset > memory.Length)
{
continue; // Add warning?
}
patchOffset -= protectedOffset;
if (patchOffset + patchSize > memory.Length)
{
patchSize = memory.Length - patchOffset; // Add warning?
}
Logger.Info?.Print(LogClass.ModLoader, $"Patching address offset {patchOffset:x} <= {BitConverter.ToString(patch).Replace('-', ' ')} len={patchSize}");
patch.AsSpan().Slice(0, patchSize).CopyTo(memory.Slice(patchOffset, patchSize));
count++;
}
return count;
}
}
}