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Migrate Utf8Formatter to Span<T>.Fill #52591

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Migrate Utf8Formatter to Span<T>.Fill #52591

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Migrate `Utf8Formatter` to `Span<T>.Fill`
xtqqczze May 11, 2021
8578d06
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xtqqczze May 11, 2021
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13 changes: 0 additions & 13 deletions ...braries/System.Private.CoreLib/src/System/Buffers/Text/Utf8Formatter/FormattingHelpers.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -33,19 +33,6 @@ public static char GetSymbolOrDefault(in StandardFormat format, char defaultSymb

#region UTF-8 Helper methods

/// <summary>
/// Fills a buffer with the ASCII character '0' (0x30).
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void FillWithAsciiZeros(Span<byte> buffer)
{
// This is a faster implementation of Span<T>.Fill().
for (int i = 0; i < buffer.Length; i++)
{
buffer[i] = (byte)'0';
}
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void WriteDigits(ulong value, Span<byte> buffer)
{
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3 changes: 2 additions & 1 deletion ...Private.CoreLib/src/System/Buffers/Text/Utf8Formatter/Utf8Formatter.Integer.Unsigned.D.cs
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Expand Up @@ -43,7 +43,8 @@ private static bool TryFormatUInt64D(ulong value, byte precision, Span<byte> des

if (leadingZeroCount > 0)
{
FormattingHelpers.FillWithAsciiZeros(destination.Slice(0, leadingZeroCount));
// Fill with ASCII zeros
destination.Slice(0, leadingZeroCount).Fill((byte)'0');
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Note that Utf8Formatter is typically going to use this method for very small sizes. Is Array.Fill faster for these small sizes?

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I run some tests, it seems the for loop may be faster for leadingZeroCount < 8.

}
FormattingHelpers.WriteDigits(value, destination.Slice(leadingZeroCount, digitCount));

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4 changes: 3 additions & 1 deletion ...Private.CoreLib/src/System/Buffers/Text/Utf8Formatter/Utf8Formatter.Integer.Unsigned.N.cs
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Expand Up @@ -48,7 +48,9 @@ private static bool TryFormatUInt64N(ulong value, byte precision, Span<byte> des
if (trailingZeroCount > 0)
{
destination[digitCount + commaCount] = Utf8Constants.Period;
FormattingHelpers.FillWithAsciiZeros(destination.Slice(digitCount + commaCount + 1, trailingZeroCount));

// Fill with ASCII zeros
destination.Slice(digitCount + commaCount + 1, trailingZeroCount).Fill((byte)'0');
}

return true;
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