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Optimise char to hex conversion #116821

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56 changes: 31 additions & 25 deletions src/libraries/Common/src/System/HexConverter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -370,32 +370,38 @@ private static bool TryDecodeFromUtf16_Scalar(ReadOnlySpan<char> chars, Span<byt

// byteHi hasn't been shifted to the high half yet, so the only way the bitwise or produces this pattern
// is if either byteHi or byteLo was not a hex character.
if ((byteLo | byteHi) == 0xFF)
if ((byteLo | byteHi) < 0)
break;

bytes[j++] = (byte)((byteHi << 4) | byteLo);
i += 2;
}

if (byteLo == 0xFF)
if (byteLo < 0)
i++;

charsProcessed = i;
return (byteLo | byteHi) != 0xFF;
return (byteLo | byteHi) >= 0;
}

/// <summary>Converts a hex character to its integer value.</summary>
/// <returns>The integer value of the hex character, or -1 if the character is not a valid hex character.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int FromChar(int c)
{
return c >= CharToHexLookup.Length ? 0xFF : CharToHexLookup[c];
return CharToHexLookup[Math.Min(c, 0xFF)];
}

/// <summary>Converts an upper hex character to its integer value.</summary>
/// <returns>The integer value of the upper hex character, or -1 if the character is not a valid upper hex character.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int FromUpperChar(int c)
{
return c > 71 ? 0xFF : CharToHexLookup[c];
return CharToHexLookup[Math.Min(c, 'F' + 1)];
}

/// <summary>Converts a lower hex character to its integer value.</summary>
/// <returns>The integer value of the lower hex character, or -1 if the character is not a valid lower hex character.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int FromLowerChar(int c)
{
Expand All @@ -405,7 +411,7 @@ public static int FromLowerChar(int c)
if ((uint)(c - 'a') <= 'f' - 'a')
return c - 'a' + 10;

return 0xFF;
return -1;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand Down Expand Up @@ -436,7 +442,7 @@ public static bool IsHexChar(int c)
return (long)(shift & mask) < 0 ? true : false;
}

return FromChar(c) != 0xFF;
return FromChar(c) >= 0;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand All @@ -451,25 +457,25 @@ public static bool IsHexLowerChar(int c)
return (uint)(c - '0') <= 9 || (uint)(c - 'a') <= ('f' - 'a');
}

/// <summary>Map from an ASCII char to its hex value, e.g. arr['b'] == 11. 0xFF means it's not a hex digit.</summary>
public static ReadOnlySpan<byte> CharToHexLookup =>
/// <summary>Map from an ASCII char to its hex value, e.g. arr['b'] == 11. -1 means it's not a hex digit.</summary>
public static ReadOnlySpan<sbyte> CharToHexLookup =>
[
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 15
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 31
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 47
0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 63
0xFF, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 79
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 95
0xFF, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 111
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 127
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 143
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 159
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 175
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 191
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 207
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 223
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 239
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF // 255
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 15
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 31
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 47
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, // 63
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 79
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 95
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 111
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 127
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 143
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 159
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 175
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 191
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 207
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 223
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 239
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 // 255
];
}
}
5 changes: 3 additions & 2 deletions src/libraries/Common/src/System/Net/IPv4AddressHelper.Common.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -263,9 +263,10 @@ internal static unsafe long ParseNonCanonical<TChar>(TChar* name, int start, ref
ch = ToUShort(name[current]);
int digitValue = HexConverter.FromChar(ch);

if (digitValue >= numberBase)
// Unsigned overflow indicates an invalid character or a terminator
if ((uint)digitValue >= (uint)numberBase)
{
break; // Invalid/terminator
break;
}
currentValue = (currentValue * numberBase) + digitValue;

Expand Down
2 changes: 1 addition & 1 deletion src/libraries/Common/src/System/Net/IPv6AddressHelper.Common.cs
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Expand Up @@ -420,7 +420,7 @@ internal static void Parse<TChar>(ReadOnlySpan<TChar> address, scoped Span<ushor
default:
int characterValue = HexConverter.FromChar(currentCh);

number = number * IPv6AddressHelper.Hex + characterValue;
number = number * IPv6AddressHelper.Hex + (byte)characterValue;
i++;
break;
}
Expand Down
2 changes: 1 addition & 1 deletion src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2030,7 +2030,7 @@ internal static byte HexByteFromChars(char char1, char char2)
{
int hi = HexConverter.FromLowerChar(char1);
int lo = HexConverter.FromLowerChar(char2);
if ((hi | lo) == 0xFF)
if ((hi | lo) < 0)
{
throw new ArgumentOutOfRangeException("idData");
}
Expand Down
5 changes: 3 additions & 2 deletions src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/W3CPropagator.cs
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Expand Up @@ -390,8 +390,9 @@ private static bool TryDecodeEscapedByte(ReadOnlySpan<char> span, out byte value
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool TryDecodeHexDigit(char c, out byte value)
{
value = (byte)HexConverter.FromChar((int)c);
return value != 0xFF; // invalid hex digit
int result = HexConverter.FromChar(c);
value = (byte)result;
return result >= 0;
}

// Allowed baggage key characters:
Expand Down
2 changes: 1 addition & 1 deletion src/libraries/System.Net.Http/src/System/Net/Http/Headers/AltSvcHeaderParser.cs
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Expand Up @@ -288,7 +288,7 @@ private static bool TryReadUnknownPercentEncodedAlpnProtocolName(ReadOnlySpan<ch
private static bool TryReadAlpnHexDigit(char ch, out int nibble)
{
int result = HexConverter.FromUpperChar(ch);
if (result == 0xFF)
if (result < 0)
{
nibble = 0;
return false;
Expand Down
4 changes: 2 additions & 2 deletions src/libraries/System.Net.HttpListener/src/System/Net/HttpListenerRequest.cs
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Expand Up @@ -433,7 +433,7 @@ private static string UrlDecodeStringFromStringInternal(string s, Encoding e)
int h3 = HexConverter.FromChar(s[pos + 4]);
int h4 = HexConverter.FromChar(s[pos + 5]);

if ((h1 | h2 | h3 | h4) != 0xFF)
if ((h1 | h2 | h3 | h4) >= 0)
{ // valid 4 hex chars
ch = (char)((h1 << 12) | (h2 << 8) | (h3 << 4) | h4);
pos += 5;
Expand All @@ -448,7 +448,7 @@ private static string UrlDecodeStringFromStringInternal(string s, Encoding e)
int h1 = HexConverter.FromChar(s[pos + 1]);
int h2 = HexConverter.FromChar(s[pos + 2]);

if ((h1 | h2) != 0xFF)
if ((h1 | h2) >= 0)
{ // valid 2 hex chars
byte b = (byte)((h1 << 4) | h2);
pos += 2;
Expand Down
2 changes: 1 addition & 1 deletion ...raries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/PhysicalAddress.cs
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Expand Up @@ -159,7 +159,7 @@ public static bool TryParse(ReadOnlySpan<char> address, [NotNullWhen(true)] out
{
int character = address[i];
int tmp;
if ((tmp = HexConverter.FromChar(character)) == 0xFF)
if ((tmp = HexConverter.FromChar(character)) < 0)
{
if (delimiter == character && validCount == validSegmentLength)
{
Expand Down
2 changes: 1 addition & 1 deletion ....NetworkInformation/src/System/Net/NetworkInformation/StringParsingHelpers.Connections.cs
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Expand Up @@ -388,7 +388,7 @@ private static IPAddress ParseIPv6HexString(ReadOnlySpan<char> hexAddress, bool
private static byte HexToByte(char val)
{
int result = HexConverter.FromChar(val);
if (result == 0xFF)
if (result < 0)
{
throw ExceptionHelper.CreateForParseFailure();
}
Expand Down
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