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ryujinx-final/Ryujinx.Graphics.Gpu/Shader/Cache/Definition/CacheManifestHeader.cs

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using System;
using System.Runtime.InteropServices;
namespace Ryujinx.Graphics.Gpu.Shader.Cache.Definition
{
/// <summary>
/// Header of the shader cache manifest.
/// </summary>
[StructLayout(LayoutKind.Sequential, Pack = 1, Size = 0x10)]
struct CacheManifestHeader
{
/// <summary>
/// The version of the cache.
/// </summary>
public ulong Version;
/// <summary>
/// The graphics api used for this cache.
/// </summary>
public CacheGraphicsApi GraphicsApi;
/// <summary>
/// The hash type used for this cache.
/// </summary>
public CacheHashType HashType;
/// <summary>
/// CRC-16 checksum over the data in the file.
/// </summary>
public ushort TableChecksum;
/// <summary>
/// Construct a new cache manifest header.
/// </summary>
/// <param name="version">The version of the cache</param>
/// <param name="graphicsApi">The graphics api used for this cache</param>
/// <param name="hashType">The hash type used for this cache</param>
public CacheManifestHeader(ulong version, CacheGraphicsApi graphicsApi, CacheHashType hashType)
{
Version = version;
GraphicsApi = graphicsApi;
HashType = hashType;
TableChecksum = 0;
}
/// <summary>
/// Update the checksum in the header.
/// </summary>
/// <param name="data">The data to perform the checksum on</param>
public void UpdateChecksum(ReadOnlySpan<byte> data)
{
TableChecksum = CalculateCrc16(data);
}
/// <summary>
/// Calculate a CRC-16 over data.
/// </summary>
/// <param name="data">The data to perform the CRC-16 on</param>
/// <returns>A CRC-16 over data</returns>
private static ushort CalculateCrc16(ReadOnlySpan<byte> data)
{
int crc = 0;
const ushort poly = 0x1021;
for (int i = 0; i < data.Length; i++)
{
crc ^= data[i] << 8;
for (int j = 0; j < 8; j++)
{
crc <<= 1;
if ((crc & 0x10000) != 0)
{
crc = (crc ^ poly) & 0xFFFF;
}
}
}
return (ushort)crc;
}
/// <summary>
/// Check the validity of the header.
/// </summary>
/// <param name="graphicsApi">The target graphics api in use</param>
/// <param name="hashType">The target hash type in use</param>
/// <param name="data">The data after this header</param>
/// <returns>True if the header is valid</returns>
/// <remarks>This doesn't check that versions match</remarks>
public bool IsValid(CacheGraphicsApi graphicsApi, CacheHashType hashType, ReadOnlySpan<byte> data)
{
return GraphicsApi == graphicsApi && HashType == hashType && TableChecksum == CalculateCrc16(data);
}
}
}