Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Optimize NumUtils.CRC16 #198

Merged
merged 5 commits into from
Apr 1, 2024
Merged

Optimize NumUtils.CRC16 #198

Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
7c46562
Optimize NumUtils.CRC16
PaulusParssinen Mar 29, 2024
3d3774b
Use regular array initializer to avoid dotnet-format bug
PaulusParssinen Mar 29, 2024
bffb3a9
Add reason for the suppression
PaulusParssinen Mar 29, 2024
0772469
Merge branch 'main' into crc16
badrishc Apr 1, 2024
682e8ae
Merge branch 'main' into crc16
vazois Apr 1, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 11 additions & 26 deletions libs/common/NumUtils.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace Garnet.common
Expand Down Expand Up @@ -399,7 +400,11 @@ internal static unsafe int IndexOfByte(byte* src, byte value, int index, int cou
return -1;
}

static readonly ushort[] CRC_TABLE = new ushort[256]
/// <summary>
/// This table is based on the CRC-16-CCITT polynomial (0x1021)
/// </summary>
#pragma warning disable IDE0300 // Simplify collection initialization. Ignored to avoid dotnet-format bug, see https://github.com/dotnet/sdk/issues/39898
private static ReadOnlySpan<ushort> Crc16Table => new ushort[256]
{
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
Expand Down Expand Up @@ -434,37 +439,17 @@ internal static unsafe int IndexOfByte(byte* src, byte value, int index, int cou
0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};
#pragma warning restore IDE0300 // Simplify collection initialization

// No need to free or track until end of process
static readonly ushort* crc_table_ptr = (ushort*)GCHandle.Alloc(CRC_TABLE, GCHandleType.Pinned).AddrOfPinnedObject();

/// <summary>
/// Compute CRC of given data
/// </summary>
/// <param name="data"></param>
/// <param name="len"></param>
/// <returns></returns>
public static unsafe ushort CRC16(byte* data, int len)
{
ushort result = 0;
byte* end = data + len;
while (data < end)
result = (ushort)(*(crc_table_ptr + (((result >> 8) ^ *data++) & 0xff)) ^ (result << 8));
return result;
}

/// <summary>
/// Compute CRC16 of given data (via array access)
/// </summary>
/// <param name="data"></param>
/// <param name="len"></param>
/// <returns></returns>
public static unsafe ushort CRC16v2(byte* data, int len)
{
ushort result = 0;
byte* end = data + len;
while (data < end)
result = (ushort)(CRC_TABLE[((result >> 8) ^ *data++) & 0xff] ^ (result << 8));
{
nuint index = (nuint)(uint)((result >> 8) ^ *data++) & 0xff;
result = (ushort)(Unsafe.Add(ref MemoryMarshal.GetReference(Crc16Table), index) ^ (result << 8));
}
return result;
}

Expand Down