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Merged
unsafePtr merged 1 commit into from
Jan 9, 2026
Merged

feat: drop vector128 for counting zeros #3

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16 changes: 13 additions & 3 deletions src/Base58Encoding.Tests/Base58DecodeFast.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -76,10 +76,20 @@ public void Decode64Fast_WithAllZeros_WorksCorrectly()
}

[Theory]
[InlineData("invalid0chars")] // Invalid character '0'
public void Decode32Fast_WithInvalidInput_ReturnsNull(string input)
[InlineData("invalid")] // Invalid character 'l'
[InlineData("0chars")] // Invalid character '0'
public void Decode64Fast_WithInvalidInput_ReturnsNull(string input)
{
Assert.Null(Base58.DecodeBitcoin64Fast(input));
Assert.Throws<ArgumentException>(() => Base58.DecodeBitcoin64Fast(input));
}

[Theory]
[InlineData("invalid")] // Invalid character 'l'
[InlineData("0chars")] // Invalid character '0'

public void Decode32ast_WithInvalidInput_ReturnsNull(string input)
{
Assert.Throws<ArgumentException>(() => Base58.DecodeBitcoin32Fast(input));
}

[Fact]
Expand Down
36 changes: 36 additions & 0 deletions src/Base58Encoding.Tests/SimpleLeadingZerosTest.cs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
using System.Runtime.Intrinsics;

namespace Base58Encoding.Tests;

public class SimpleLeadingZerosTest
Expand Down Expand Up @@ -27,4 +29,38 @@ public void BitcoinAddress_CountLeadingZerosMultipleWays_SameResult()

Assert.Equal(simdScalarCount, manualCount);
}

[Theory]
[InlineData(5)]
[InlineData(12)]
[InlineData(13)]
[InlineData(23)]
[InlineData(31)]
public void CountLeadingZeros_32Size_ReturnsCorrectNumber(int zerosCount)
{
// Arrange
var data = new byte[32];
data.AsSpan(0, zerosCount).Fill(0x00);
Random.Shared.NextBytes(data.AsSpan(zerosCount));

// Act
var result = Base58.CountLeadingZerosSimd(data, out var processed);

Assert.Equal(zerosCount, result);
Assert.Equal(data.Length, processed);
}

[Fact]
public void CountLeadingZeros_512Size_ReturnsCorrectNumber()
{
// Arrange
var zerosCount = 123;
var data = new byte[512];
data.AsSpan(0, zerosCount).Fill(0x00);
Random.Shared.NextBytes(data.AsSpan(zerosCount));
// Act
var result = Base58.CountLeadingZerosSimd(data, out var processed);
Assert.Equal(zerosCount, result);
Assert.Equal(Vector256<byte>.Count * 4, processed); // Vector256 used 4 times
}
}
20 changes: 0 additions & 20 deletions src/Base58Encoding/Base58.CountLeading.cs
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Expand Up @@ -45,26 +45,6 @@ internal static int CountLeadingZerosSimd(ReadOnlySpan<byte> data, out int proce
length -= Vector256<byte>.Count;
}
}
else if (Vector128.IsHardwareAccelerated && length >= Vector128<byte>.Count)
{
var zeroVector = Vector128<byte>.Zero;

while (length >= Vector128<byte>.Count)
{
var vector = Vector128.LoadUnsafe(ref searchSpace, (nuint)count);
var comparison = Vector128.Equals(vector, zeroVector);
uint mask = comparison.ExtractMostSignificantBits();

if (mask != ushort.MaxValue)
{
processed = count + Vector128<byte>.Count;
return count + BitOperations.TrailingZeroCount(~mask);
}

count += Vector128<byte>.Count;
length -= Vector128<byte>.Count;
}
}

processed = count;
return count;
Expand Down
22 changes: 13 additions & 9 deletions src/Base58Encoding/Base58.Decode.cs
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Expand Up @@ -114,16 +114,16 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
else
{
char c = encoded[j - prepend0];
// Validate + convert using Bitcoin decode table (return null for invalid chars)
// Validate + convert using Bitcoin decode table
if (c >= 128 || bitcoinDecodeTable[c] == 255)
return null;
ThrowHelper.ThrowInvalidCharacter(c);

rawBase58[j] = bitcoinDecodeTable[c];
}
}

// Convert to intermediate format (base 58^5)
Span<ulong> intermediate = stackalloc ulong[Base58BitcoinTables.IntermediateSz32]; // 9 elements
Span<ulong> intermediate = stackalloc ulong[Base58BitcoinTables.IntermediateSz32];

for (int i = 0; i < Base58BitcoinTables.IntermediateSz32; i++)
{
Expand All @@ -135,7 +135,7 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
}

// Convert to overcomplete base 2^32 using decode table
Span<ulong> binary = stackalloc ulong[Base58BitcoinTables.BinarySz32]; // 8 elements
Span<ulong> binary = stackalloc ulong[Base58BitcoinTables.BinarySz32];

for (int j = 0; j < Base58BitcoinTables.BinarySz32; j++)
{
Expand Down Expand Up @@ -183,6 +183,8 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
}

// Leading zeros in output must match leading '1's in input
// might be edge case since base58 of 32bytes can be between 32 and 44 characters.
// will be handled by generic decoder if lengths don't match
if (outputLeadingZeros != inputLeadingOnes) return null;

// Return the full 32 bytes - the result should always be 32 bytes for 32-byte decode
Expand All @@ -194,7 +196,7 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
int charCount = encoded.Length;

// Convert to raw base58 digits with validation + conversion in one pass
Span<byte> rawBase58 = stackalloc byte[Base58BitcoinTables.Raw58Sz64]; // 90 bytes
Span<byte> rawBase58 = stackalloc byte[Base58BitcoinTables.Raw58Sz64];
var bitcoinDecodeTable = Base58Alphabet.Bitcoin.DecodeTable.Span;

// Prepend zeros to make exactly Raw58Sz64 characters
Expand All @@ -208,16 +210,16 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
else
{
char c = encoded[j - prepend0];
// Validate + convert using Bitcoin decode table (return null for invalid chars)
// Validate + convert using Bitcoin decode table
if (c >= 128 || bitcoinDecodeTable[c] == 255)
return null;
ThrowHelper.ThrowInvalidCharacter(c);

rawBase58[j] = bitcoinDecodeTable[c];
}
}

// Convert to intermediate format (base 58^5)
Span<ulong> intermediate = stackalloc ulong[Base58BitcoinTables.IntermediateSz64]; // 18 elements
Span<ulong> intermediate = stackalloc ulong[Base58BitcoinTables.IntermediateSz64];

for (int i = 0; i < Base58BitcoinTables.IntermediateSz64; i++)
{
Expand All @@ -229,7 +231,7 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
}

// Convert to overcomplete base 2^32 using decode table
Span<ulong> binary = stackalloc ulong[Base58BitcoinTables.BinarySz64]; // 16 elements
Span<ulong> binary = stackalloc ulong[Base58BitcoinTables.BinarySz64];

for (int j = 0; j < Base58BitcoinTables.BinarySz64; j++)
{
Expand Down Expand Up @@ -277,6 +279,8 @@ internal byte[] DecodeGeneric(ReadOnlySpan<char> encoded)
}

// Leading zeros in output must match leading '1's in input
// might be edge case since base58 of 64bytes can be between 64 and 88 characters.
// will be handled by generic decoder if lengths don't match
if (outputLeadingZeros != inputLeadingOnes) return null;

// Return the full 64 bytes - the result should always be 64 bytes for 64-byte decode
Expand Down
12 changes: 0 additions & 12 deletions src/Base58Encoding/Base58.Encode.cs
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Expand Up @@ -93,7 +93,6 @@ internal string EncodeGeneric(ReadOnlySpan<byte> data)

internal static string EncodeBitcoin32Fast(ReadOnlySpan<byte> data)
{
// Count leading zeros (needed for final output)
int inLeadingZeros = CountLeadingZeros(data);

if (inLeadingZeros == data.Length)
Expand Down Expand Up @@ -140,8 +139,6 @@ internal static string EncodeBitcoin32Fast(ReadOnlySpan<byte> data)
rawBase58[5 * i + 2] = (byte)((v / 3364U) % 58U);
rawBase58[5 * i + 1] = (byte)((v / 195112U) % 58U);
rawBase58[5 * i + 0] = (byte)(v / 11316496U);

// Continue processing all values
}

// Count leading zeros in raw output
Expand All @@ -156,12 +153,9 @@ internal static string EncodeBitcoin32Fast(ReadOnlySpan<byte> data)
Debug.Assert(skip >= 0, "rawLeadingZeros should always be >= inLeadingZeros by Base58 math");
int outputLength = Base58BitcoinTables.Raw58Sz32 - skip;

// Create state for string.Create
var state = new EncodeFastState(rawBase58, inLeadingZeros, rawLeadingZeros, outputLength);

return string.Create(outputLength, state, static (span, state) =>
{
// Fill leading '1's for input leading zeros
if (state.InLeadingZeros > 0)
{
span[..state.InLeadingZeros].Fill('1');
Expand All @@ -181,7 +175,6 @@ internal static string EncodeBitcoin32Fast(ReadOnlySpan<byte> data)

private static string EncodeBitcoin64Fast(ReadOnlySpan<byte> data)
{
// Count leading zeros (needed for final output)
int inLeadingZeros = CountLeadingZeros(data);

if (inLeadingZeros == data.Length)
Expand Down Expand Up @@ -242,7 +235,6 @@ private static string EncodeBitcoin64Fast(ReadOnlySpan<byte> data)
rawBase58[5 * i + 1] = (byte)((v / 195112U) % 58U);
rawBase58[5 * i + 0] = (byte)(v / 11316496U);

// Debug.Assert - ensure all values are valid Base58 digits (algorithm correctness check)
Debug.Assert(rawBase58[5 * i + 0] < 58 && rawBase58[5 * i + 1] < 58 &&
rawBase58[5 * i + 2] < 58 && rawBase58[5 * i + 3] < 58 &&
rawBase58[5 * i + 4] < 58,
Expand All @@ -256,17 +248,13 @@ private static string EncodeBitcoin64Fast(ReadOnlySpan<byte> data)
if (rawBase58[rawLeadingZeros] != 0) break;
}

// Calculate skip and final length
int skip = rawLeadingZeros - inLeadingZeros;
Debug.Assert(skip >= 0, "rawLeadingZeros should always be >= inLeadingZeros by Base58 math");
int outputLength = Base58BitcoinTables.Raw58Sz64 - skip;

// Create state for string.Create
var state = new EncodeFastState(rawBase58, inLeadingZeros, rawLeadingZeros, outputLength);

return string.Create(outputLength, state, static (span, state) =>
{
// Fill leading '1's for input leading zeros
if (state.InLeadingZeros > 0)
{
span[..state.InLeadingZeros].Fill('1');
Expand Down