High-Performance hexadecimal converter with support of Span<T> and buffering.
Available on nuget
PM> Install-Package HexConverter
Requirements:
- System.Memory (>= 4.5.3)
Dotnet core implementation do not take advantage of Span<T> to slice the memory without allocations and don't use stackalloc/pooled memory to avoid heap allocations, making the code slow.
Using Linq
As you can see you have allocations for each two char in the hexString because is doing a substring and you have an allocation for the byte array.
string hexString = "01AAB1DC10DD";
bytes[] bytes = Enumerable.Range(0, hexString.Length)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(hexString.Substring(x, 2), 16))
.ToArray()
/*bytes items:
{ 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD }
*/Using HexConverter
You get just the allocation for the final array.
string hexString = "01AAB1DC10DD";
bytes[] bytes = HexConverter.GetBytes(hexString);
/*bytes items:
{ 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD }
*/Using HexConverter with pooled array
Zero allocation, and easy to use. Optimise for strings longer than 100 characters.
string hexString = "01AAB1DC10DD";
using var pooledBytes = HexConverter.GetBytesPooled(hexString);
/*bytes.ArraySegment items:
{ 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD }
*/Using HexConverter with stackalloc buffer
Zero allocation, and optimise for small hex string.
string hexString = "01AAB1DC10DD";
Span<byte> buffer = stackalloc byte[HexConverter.GetBytesCount(hexString)];
int count = HexConverter.GetBytes(hexString, buffer);
/*buffer items:
{ 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD }
*/Using Linq
With this linq implementation you have allocation for the intermidiate array, and a string per each byte and the a new one for the final string.
byte[] vals = { 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD };
string str = string.Concat(vals.Select(b => b.ToString("x2")));
Console.WriteLine(str);
/*Output:
01AAB1DC10DD
*/Using HexConverter
You get just the allocation for the final string.
byte[] vals = { 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD };
string str = HexConverter.GetString(vals);
Console.WriteLine(str);
/*Output:
01AAB1DC10DD
*/Using HexConverter with pooled array
Zero allocation, and easy to use. Optimise for array longer than 100 items.
byte[] vals = { 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD };
using var pooledChars = HexConverter.GetCharsPooled(vals);
Console.WriteLine(pooledChars.ArraySegment.AsSpan());
/*Output:
01AAB1DC10DD
*/Using HexConverter with stackalloc buffer
Zero allocation, and optimise for small byte arrays.
byte[] vals = { 0x01, 0xAA, 0xB1, 0xDC, 0x10, 0xDD };
Span<byte> buffer = stackalloc byte[HexConverter.GetBytesCount(vals)];
HexConverter.GetChars(vals, buffer);
Console.WriteLine(buffer.AsSpan());
/*Output:
01AAB1DC10DD
*/Lower is better
Lower is better
