c# SimpleFixParser

SimpleFixParser_span.cs

public static KeyValuePair<ushort, string>[] Parse(Span<byte> message)
{
    var values = new List<KeyValuePair<ushort, string>>();
    const byte Soh = 1;
    const byte Equals = 61;
    while (0 < message.Length)
    {
        var soh = message.IndexOf(Soh);
        if (-1 == soh)
            break;
        var kvp = message.Slice(0, soh);
        var equals = kvp.IndexOf(Equals);
        if (-1 != equals && Utf8Parser.TryParse(kvp.Slice(0, equals), out ushort key, out _))
        {
            var value = Encoding.ASCII.GetString(kvp.Slice(equals + 1, kvp.Length - equals - 1));
            values.Add(new KeyValuePair<ushort, string>(key, value));
        }
        message = message.Slice(soh + 1);
    }
    
    return values.ToArray();
}

SimpleFixParser_string.cs

public static class SimpleFixParser
{
    public static IEnumerable<KeyValuePair<ushort, string>> Parse(string message)
    {
        var values = message.Split((char) 1, StringSplitOptions.RemoveEmptyEntries);
        foreach (var kvp in values)
        {
            var deliminator = kvp.IndexOf('=');
            var tag = ushort.Parse(kvp.Substring(0, deliminator));
            var value = kvp.Substring(deliminator + 1);
            yield return new KeyValuePair<ushort, string>(tag, value);
        }
    }
}