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Use ReadOnlySpan<byte> static data compiler optimization in more places #2101

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Merged
merged 1 commit into from
Apr 28, 2022
Merged

Use ReadOnlySpan<byte> static data compiler optimization in more places #2101

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5 changes: 3 additions & 2 deletions src/ImageSharp/Formats/Webp/Lossy/QuantEnc.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,6 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossy
/// </summary>
internal static unsafe class QuantEnc
{
private static readonly byte[] Zigzag = { 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15 };

private static readonly ushort[] WeightY = { 38, 32, 20, 9, 32, 28, 17, 7, 20, 17, 10, 4, 9, 7, 4, 2 };

private const int MaxLevel = 2047;
Expand Down Expand Up @@ -47,6 +45,9 @@ internal static unsafe class QuantEnc
private const int DSHIFT = 4;
private const int DSCALE = 1; // storage descaling, needed to make the error fit byte

// This uses C#'s optimization to refer to the static data segment of the assembly, no allocation occurs.
private static ReadOnlySpan<byte> Zigzag => new byte[] { 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15 };

public static void PickBestIntra16(Vp8EncIterator it, ref Vp8ModeScore rd, Vp8SegmentInfo[] segmentInfos, Vp8EncProba proba)
{
const int numBlocks = 16;
Expand Down
11 changes: 7 additions & 4 deletions src/ImageSharp/Formats/Webp/Lossy/Vp8Matrix.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.

using System;

namespace SixLabors.ImageSharp.Formats.Webp.Lossy
{
internal unsafe struct Vp8Matrix
Expand All @@ -13,10 +15,6 @@ internal unsafe struct Vp8Matrix
new[] { 110, 115 }
};

// Sharpening by (slightly) raising the hi-frequency coeffs.
// Hack-ish but helpful for mid-bitrate range. Use with care.
private static readonly byte[] FreqSharpening = { 0, 30, 60, 90, 30, 60, 90, 90, 60, 90, 90, 90, 90, 90, 90, 90 };

/// <summary>
/// Number of descaling bits for sharpening bias.
/// </summary>
Expand Down Expand Up @@ -47,6 +45,11 @@ internal unsafe struct Vp8Matrix
/// </summary>
public fixed short Sharpen[16];

// Sharpening by (slightly) raising the hi-frequency coeffs.
// Hack-ish but helpful for mid-bitrate range. Use with care.
// This uses C#'s optimization to refer to the static data segment of the assembly, no allocation occurs.
private static ReadOnlySpan<byte> FreqSharpening => new byte[] { 0, 30, 60, 90, 30, 60, 90, 90, 60, 90, 90, 90, 90, 90, 90, 90 };

/// <summary>
/// Returns the average quantizer.
/// </summary>
Expand Down