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Replace MimeReader calls to IndexOf('\n') with new EndOfLine() method
This was an attempt at overcoming the performance degradation of using
Span<byte> in place of raw pointers in MimeReader, specifically for
the .NET 4.x frameworks.
Unfortunately, this new custom implementation (based on the previous
pointer-based optimizations I had written) is actually slightly slower
than Span<byte>.indexOf('\n').
Need to figure out a better solution...- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,98 @@ | ||
| // | ||
| // SpanExtensions.cs | ||
| // | ||
| // Author: Jeffrey Stedfast <[email protected]> | ||
| // | ||
| // Copyright (c) 2013-2025 .NET Foundation and Contributors | ||
| // | ||
| // Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| // of this software and associated documentation files (the "Software"), to deal | ||
| // in the Software without restriction, including without limitation the rights | ||
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| // copies of the Software, and to permit persons to whom the Software is | ||
| // furnished to do so, subject to the following conditions: | ||
| // | ||
| // The above copyright notice and this permission notice shall be included in | ||
| // all copies or substantial portions of the Software. | ||
| // | ||
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | ||
| // THE SOFTWARE. | ||
| // | ||
|
|
||
| using System; | ||
| using System.Runtime.CompilerServices; | ||
| using System.Runtime.InteropServices; | ||
|
|
||
| namespace MimeKit.Utils { | ||
| static class SpanExtensions | ||
| { | ||
| #if NET8_0_OR_GREATER | ||
| [MethodImpl (MethodImplOptions.AggressiveInlining)] | ||
| public static int EndOfLine (this Span<byte> span) | ||
| { | ||
| // Note: Span<byte>.IndexOf(byte) is insanely fast in .NET >= 8.0, so use it. | ||
| return span.IndexOf ((byte) '\n'); | ||
| } | ||
| #else | ||
| [MethodImpl (MethodImplOptions.AggressiveInlining)] | ||
| public unsafe static int EndOfLine (this Span<byte> span) | ||
| { | ||
| fixed (byte* inbuf = &MemoryMarshal.GetReference (span)) { | ||
| byte* inptr = inbuf; | ||
|
|
||
| // scan for a linefeed character until we are 4-byte aligned. | ||
| switch (((long) inptr) & 0x03) { | ||
| case 1: | ||
| if (*inptr == (byte) '\n') | ||
| return (int) (inptr - inbuf); | ||
| inptr++; | ||
| goto case 2; | ||
| case 2: | ||
| if (*inptr == (byte) '\n') | ||
| return (int) (inptr - inbuf); | ||
| inptr++; | ||
| goto case 3; | ||
| case 3: | ||
| if (*inptr == (byte) '\n') | ||
| return (int) (inptr - inbuf); | ||
| inptr++; | ||
| break; | ||
| } | ||
|
|
||
| // -funroll-loops, yippee ki-yay. | ||
| uint* dword = (uint*) inptr; | ||
| uint mask; | ||
|
|
||
| do { | ||
| mask = *dword ^ 0x0A0A0A0A; | ||
| mask = ((mask - 0x01010101) & (~mask & 0x80808080)); | ||
|
|
||
| if (mask != 0) | ||
| break; | ||
|
|
||
| dword++; | ||
| } while (true); | ||
|
|
||
| inptr = (byte*) dword; | ||
| int offset = (int) (inptr - inbuf); | ||
|
|
||
| if (inptr[0] == (byte) '\n') | ||
| return offset; | ||
|
|
||
| if (inptr[1] == (byte) '\n') | ||
| return offset + 1; | ||
|
|
||
| if (inptr[2] == (byte) '\n') | ||
| return offset + 2; | ||
|
|
||
| return offset + 3; | ||
| } | ||
| } | ||
| #endif | ||
| } | ||
| } |