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Minor PNG Encoding Optimization for DeflaterEngine and WuQuantizer #2023

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Merged
merged 4 commits into from
Mar 4, 2022
Merged

Minor PNG Encoding Optimization for DeflaterEngine and WuQuantizer #2023

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025e526
Minor Optimization for DeflaterEngine and WuQuantizer
ratok-mk Feb 18, 2022
a30f40c
Apply suggestions from code review
ratok-mk Feb 22, 2022
0b1cf1c
Update DeflaterEngine.cs
ratok-mk Feb 22, 2022
f774f45
Merge branch 'main' into mk/optimize-PNG-encoding
JimBobSquarePants Mar 3, 2022
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22 changes: 14 additions & 8 deletions src/ImageSharp/Compression/Zlib/DeflaterEngine.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -483,18 +483,21 @@ private bool FindLongestMatch(int curMatch)
int niceLength = Math.Min(this.niceLength, this.lookahead);

int matchStrt = this.matchStart;
this.matchLen = Math.Max(this.matchLen, DeflaterConstants.MIN_MATCH - 1);
int matchLength = this.matchLen;
matchLength = Math.Max(matchLength, DeflaterConstants.MIN_MATCH - 1);
this.matchLen = matchLength;

if (scan + matchLength > scanMax)
if (scan > scanMax - matchLength)
{
return false;
}

int scanEndPosition = scan + matchLength;

byte* pinnedWindow = this.pinnedWindowPointer;
int scanStart = this.strstart;
byte scanEnd1 = pinnedWindow[scan + matchLength - 1];
byte scanEnd = pinnedWindow[scan + matchLength];
byte scanEnd1 = pinnedWindow[scanEndPosition - 1];
byte scanEnd = pinnedWindow[scanEndPosition];

// Do not waste too much time if we already have a good match:
if (matchLength >= this.goodLength)
Expand All @@ -508,8 +511,9 @@ private bool FindLongestMatch(int curMatch)
match = curMatch;
scan = scanStart;

if (pinnedWindow[match + matchLength] != scanEnd
|| pinnedWindow[match + matchLength - 1] != scanEnd1
int matchEndPosition = match + matchLength;
if (pinnedWindow[matchEndPosition] != scanEnd
|| pinnedWindow[matchEndPosition - 1] != scanEnd1
|| pinnedWindow[match] != pinnedWindow[scan]
|| pinnedWindow[++match] != pinnedWindow[++scan])
{
Expand Down Expand Up @@ -685,6 +689,7 @@ private bool DeflateFast(bool flush, bool finish)
return false;
}

const int windowLen = (2 * DeflaterConstants.WSIZE) - DeflaterConstants.MIN_LOOKAHEAD;
while (this.lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush)
{
if (this.lookahead == 0)
Expand All @@ -695,7 +700,7 @@ private bool DeflateFast(bool flush, bool finish)
return false;
}

if (this.strstart > (2 * DeflaterConstants.WSIZE) - DeflaterConstants.MIN_LOOKAHEAD)
if (this.strstart > windowLen)
{
// slide window, as FindLongestMatch needs this.
// This should only happen when flushing and the window
Expand Down Expand Up @@ -766,6 +771,7 @@ private bool DeflateSlow(bool flush, bool finish)
return false;
}

const int windowLen = (2 * DeflaterConstants.WSIZE) - DeflaterConstants.MIN_LOOKAHEAD;
while (this.lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush)
{
if (this.lookahead == 0)
Expand All @@ -783,7 +789,7 @@ private bool DeflateSlow(bool flush, bool finish)
return false;
}

if (this.strstart >= (2 * DeflaterConstants.WSIZE) - DeflaterConstants.MIN_LOOKAHEAD)
if (this.strstart >= windowLen)
{
// slide window, as FindLongestMatch needs this.
// This should only happen when flushing and the window
Expand Down
22 changes: 13 additions & 9 deletions src/ImageSharp/Processing/Processors/Quantization/WuQuantizer{TPixel}.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -176,9 +176,10 @@ public readonly byte GetQuantizedColor(TPixel color, out TPixel match)
Rgba32 rgba = default;
color.ToRgba32(ref rgba);

int r = rgba.R >> (8 - IndexBits);
int g = rgba.G >> (8 - IndexBits);
int b = rgba.B >> (8 - IndexBits);
const int shift = 8 - IndexBits;
int r = rgba.R >> shift;
int g = rgba.G >> shift;
int b = rgba.B >> shift;
int a = rgba.A >> (8 - IndexAlphaBits);

ReadOnlySpan<byte> tagSpan = this.tagsOwner.GetSpan();
Expand Down Expand Up @@ -413,6 +414,9 @@ private void Get3DMoments(MemoryAllocator allocator)
Span<Moment> momentSpan = this.momentsOwner.GetSpan();
Span<Moment> volumeSpan = volume.GetSpan();
Span<Moment> areaSpan = area.GetSpan();
const int indexBits2 = IndexBits * 2;
const int indexAndAlphaBits = IndexBits + IndexAlphaBits;
const int indexBitsAndAlphaBits1 = IndexBits + IndexAlphaBits + 1;
int baseIndex = GetPaletteIndex(1, 0, 0, 0);

for (int r = 1; r < IndexCount; r++)
Expand All @@ -421,9 +425,9 @@ private void Get3DMoments(MemoryAllocator allocator)
// immediate outer loop. See https://github.com/dotnet/runtime/issues/61420
// To ensure the calculation doesn't happen repeatedly, hoist some of the calculations
// in the form of ind1* manually.
int ind1R = (r << ((IndexBits * 2) + IndexAlphaBits)) +
(r << (IndexBits + IndexAlphaBits + 1)) +
(r << (IndexBits * 2)) +
int ind1R = (r << (indexBits2 + IndexAlphaBits)) +
(r << indexBitsAndAlphaBits1) +
(r << indexBits2) +
(r << (IndexBits + 1)) +
r;

Expand All @@ -432,7 +436,7 @@ private void Get3DMoments(MemoryAllocator allocator)
for (int g = 1; g < IndexCount; g++)
{
int ind1G = ind1R +
(g << (IndexBits + IndexAlphaBits)) +
(g << indexAndAlphaBits) +
(g << IndexBits) +
g;
int r_g = r + g;
Expand All @@ -446,7 +450,7 @@ private void Get3DMoments(MemoryAllocator allocator)
b;

Moment line = default;

int bIndexAlphaOffset = b * IndexAlphaCount;
for (int a = 1; a < IndexAlphaCount; a++)
{
int ind1 = ind1B + a;
Expand All @@ -455,7 +459,7 @@ private void Get3DMoments(MemoryAllocator allocator)

areaSpan[a] += line;

int inv = (b * IndexAlphaCount) + a;
int inv = bIndexAlphaOffset + a;
volumeSpan[inv] += areaSpan[a];

int ind2 = ind1 - baseIndex;
Expand Down