Remove Linq from ECDSA and UInt classes

src/neo/Cryptography/Crypto.cs

@@ -25,8 +25,8 @@ public byte[] Sign(byte[] message, byte[] prikey, byte[] pubkey)
                 D = prikey,
                 Q = new ECPoint
                 {
-                    X = pubkey.Take(32),
-                    Y = pubkey.Skip(32)
+                    X = pubkey[..32],
+                    Y = pubkey[32..]
                 }
             }))
             {
@@ -40,7 +40,7 @@ public bool VerifySignature(byte[] message, byte[] signature, byte[] pubkey)
             {
                 try
                 {
-                    pubkey = ECC.ECPoint.DecodePoint(pubkey, ECC.ECCurve.Secp256r1).EncodePoint(false).Skip(1);
+                    pubkey = ECC.ECPoint.DecodePoint(pubkey, ECC.ECCurve.Secp256r1).EncodePoint(false)[1..];
                 }
                 catch
                 {
@@ -49,7 +49,7 @@ public bool VerifySignature(byte[] message, byte[] signature, byte[] pubkey)
             }
             else if (pubkey.Length == 65 && pubkey[0] == 0x04)
             {
-                pubkey = pubkey.Skip(1);
+                pubkey = pubkey[1..];
             }
             else if (pubkey.Length != 64)
             {
@@ -60,8 +60,8 @@ public bool VerifySignature(byte[] message, byte[] signature, byte[] pubkey)
                 Curve = ECCurve.NamedCurves.nistP256,
                 Q = new ECPoint
                 {
-                    X = pubkey.Take(32),
-                    Y = pubkey.Skip(32)
+                    X = pubkey[..32],
+                    Y = pubkey[32..]
                 }
             }))
             {

src/neo/Cryptography/ECC/ECPoint.cs

@@ -111,7 +111,7 @@ public static ECPoint DeserializeFrom(BinaryReader reader, ECCurve curve)
                         {
                             throw new FormatException();
                         }
-                        return DecodePoint(buffer.Take(1 + curve.ExpectedECPointLength), curve);
+                        return DecodePoint(buffer[..(1 + curve.ExpectedECPointLength)], curve);
                     }
                 case 0x04:
                     {
@@ -169,10 +169,10 @@ public static ECPoint FromBytes(byte[] pubkey, ECCurve curve)
                     return DecodePoint(pubkey, curve);
                 case 64:
                 case 72:
-                    return DecodePoint(new byte[] { 0x04 }.Concat(pubkey.Skip(pubkey.Length - 64)), curve);
+                    return DecodePoint(new byte[] { 0x04 }.Concat(pubkey[^64..]), curve);
                 case 96:
                 case 104:
-                    return DecodePoint(new byte[] { 0x04 }.Concat(pubkey.Take(pubkey.Length - 96, 64)), curve);
+                    return DecodePoint(new byte[] { 0x04 }.Concat(pubkey[^96..^32]), curve);
                 default:
                     throw new FormatException();
             }

src/neo/Cryptography/Helper.cs

@@ -77,9 +77,9 @@ public static byte[] Base58CheckDecode(this string input)
             byte[] buffer = Base58.Decode(input);
             if (buffer.Length < 4) throw new FormatException();
             byte[] checksum = buffer.Sha256(0, buffer.Length - 4).Sha256();
-            if (!Neo.Helper.MemoryEquals(buffer.Skip(buffer.Length - 4), checksum.Take(4)))
+            if (!buffer.AsSpan(^4).SequenceEqual(checksum.AsSpan(..4)))
                 throw new FormatException();
-            var ret = buffer.Take(buffer.Length - 4);
+            var ret = buffer[..^4];
             Array.Clear(buffer, 0, buffer.Length);
             return ret;
         }

src/neo/Helper.cs

@@ -17,82 +17,6 @@ public static class Helper
     {
         private static readonly DateTime unixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 
-        #region Avoid Linq
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public unsafe static bool MemoryEquals(ReadOnlySpan<byte> x, ReadOnlySpan<byte> y)
-        {
-            if (x == y) return true;
-            int len = x.Length;
-            if (len != y.Length) return false;
-            if (len == 0) return true;
-            fixed (byte* xp = x, yp = y)
-            {
-                long* xlp = (long*)xp, ylp = (long*)yp;
-                for (; len >= 8; len -= 8)
-                {
-                    if (*xlp != *ylp) return false;
-                    xlp++;
-                    ylp++;
-                }
-                byte* xbp = (byte*)xlp, ybp = (byte*)ylp;
-                for (; len > 0; len--)
-                {
-                    if (*xbp != *ybp) return false;
-                    xbp++;
-                    ybp++;
-                }
-            }
-            return true;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static T[] Reverse<T>(this T[] origin)
-        {
-            var ret = new T[origin.Length];
-            for (int x = 0, m = ret.Length - 1; x <= m; x++)
-            {
-                ret[x] = origin[m - x];
-            }
-            return ret;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static byte[] Skip(this byte[] a, int index)
-        {
-            var length = a.Length - index;
-
-            if (length < 0) throw new ArgumentException(nameof(a));
-
-            var ret = new byte[length];
-            Buffer.BlockCopy(a, index, ret, 0, length);
-            return ret;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static byte[] Take(this byte[] a, int count) => Take(a, 0, count);
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static byte[] Take(this byte[] a, int index, int count)
-        {
-            if (count < 0) throw new ArgumentException(nameof(count));
-
-            var ret = new byte[count];
-            Buffer.BlockCopy(a, index, ret, 0, count);
-            return ret;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static byte[] Concat(this byte[] a, byte[] b)
-        {
-            var ret = new byte[a.Length + b.Length];
-            Buffer.BlockCopy(a, 0, ret, 0, a.Length);
-            Buffer.BlockCopy(b, 0, ret, a.Length, b.Length);
-            return ret;
-        }
-
-        #endregion
-
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static int BitLen(int w)
         {
@@ -111,6 +35,15 @@ private static int BitLen(int w)
                 : (w < 1 << 29 ? (w < 1 << 28 ? 28 : 29) : (w < 1 << 30 ? 30 : 31)))));
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static byte[] Concat(this byte[] a, byte[] b)
+        {
+            var ret = new byte[a.Length + b.Length];
+            Buffer.BlockCopy(a, 0, ret, 0, a.Length);
+            Buffer.BlockCopy(b, 0, ret, a.Length, b.Length);
+            return ret;
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal static int GetBitLength(this BigInteger i)
         {
@@ -257,15 +190,22 @@ internal static bool TestBit(this BigInteger i, int index)
             return (i & (BigInteger.One << index)) > BigInteger.Zero;
         }
 
-
-        public static string ToHexString(this IEnumerable<byte> value)
+        public static string ToHexString(this byte[] value)
         {
             StringBuilder sb = new StringBuilder();
             foreach (byte b in value)
                 sb.AppendFormat("{0:x2}", b);
             return sb.ToString();
         }
 
+        public static string ToHexString(this byte[] value, bool reverse = false)
+        {
+            StringBuilder sb = new StringBuilder();
+            for (int i = 0; i < value.Length; i++)
+                sb.AppendFormat("{0:x2}", value[reverse ? value.Length - i - 1 : i]);
+            return sb.ToString();
+        }
+
         public static string ToHexString(this ReadOnlySpan<byte> value)
         {
             StringBuilder sb = new StringBuilder();

src/neo/IO/Caching/DataCache.cs

@@ -129,7 +129,7 @@ public IEnumerable<KeyValuePair<TKey, TValue>> Find(byte[] key_prefix = null)
             lock (dictionary)
             {
                 cached = dictionary
-                    .Where(p => p.Value.State != TrackState.Deleted && (key_prefix == null || p.Key.ToArray().Take(key_prefix.Length).SequenceEqual(key_prefix)))
+                    .Where(p => p.Value.State != TrackState.Deleted && (key_prefix == null || p.Key.ToArray().AsSpan().StartsWith(key_prefix)))
                     .Select(p =>
                     (
                         KeyBytes: p.Key.ToArray(),

src/neo/IO/Data/LevelDB/Helper.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 
 namespace Neo.IO.Data.LevelDB
 {
@@ -26,7 +25,7 @@ public static IEnumerable<T> Find<T>(this DB db, ReadOptions options, Slice pref
                     byte[] x = key.ToArray();
                     byte[] y = prefix.ToArray();
                     if (x.Length < y.Length) break;
-                    if (!x.Take(y.Length).SequenceEqual(y)) break;
+                    if (!x.AsSpan().StartsWith(y)) break;
                     yield return resultSelector(key, it.Value());
                 }
             }

src/neo/Network/P2P/Peer.cs

@@ -90,7 +90,8 @@ protected void ConnectToPeer(IPEndPoint endPoint, bool isTrusted = false)
 
         private static bool IsIntranetAddress(IPAddress address)
         {
-            byte[] data = address.MapToIPv4().GetAddressBytes().Reverse();
+            byte[] data = address.MapToIPv4().GetAddressBytes();
+            Array.Reverse(data);
             uint value = data.ToUInt32(0);
             return (value & 0xff000000) == 0x0a000000 || (value & 0xff000000) == 0x7f000000 || (value & 0xfff00000) == 0xac100000 || (value & 0xffff0000) == 0xc0a80000 || (value & 0xffff0000) == 0xa9fe0000;
         }

src/neo/SmartContract/ContractParametersContext.cs

@@ -153,7 +153,7 @@ public bool AddSignature(Contract contract, ECPoint pubkey, byte[] signature)
                     }
                     while (contract.Script[i++] == 33)
                     {
-                        points.Add(ECPoint.DecodePoint(contract.Script.Skip(i).Take(33).ToArray(), ECCurve.Secp256r1));
+                        points.Add(ECPoint.DecodePoint(contract.Script[i..^(i + 33)], ECCurve.Secp256r1));
                         i += 33;
                     }
                 }
@@ -256,9 +256,9 @@ public Witness[] GetWitnesses()
                 ContextItem item = ContextItems[ScriptHashes[i]];
                 using (ScriptBuilder sb = new ScriptBuilder())
                 {
-                    foreach (ContractParameter parameter in item.Parameters.Reverse())
+                    for (int j = item.Parameters.Length - 1; j >= 0; j--)
                     {
-                        sb.EmitPush(parameter);
+                        sb.EmitPush(item.Parameters[j]);
                     }
                     witnesses[i] = new Witness
                     {

src/neo/SmartContract/InteropService.NEO.cs

@@ -250,7 +250,7 @@ private static bool Storage_Find(ApplicationEngine engine)
                 if (!CheckStorageContext(engine, context)) return false;
                 byte[] prefix = engine.CurrentContext.EvaluationStack.Pop().GetSpan().ToArray();
                 byte[] prefix_key = StorageKey.CreateSearchPrefix(context.ScriptHash, prefix);
-                StorageIterator iterator = engine.AddDisposable(new StorageIterator(engine.Snapshot.Storages.Find(prefix_key).Where(p => p.Key.Key.Take(prefix.Length).SequenceEqual(prefix)).GetEnumerator()));
+                StorageIterator iterator = engine.AddDisposable(new StorageIterator(engine.Snapshot.Storages.Find(prefix_key).Where(p => p.Key.Key.AsSpan().StartsWith(prefix)).GetEnumerator()));
                 engine.CurrentContext.EvaluationStack.Push(StackItem.FromInterface(iterator));
                 return true;
             }

src/neo/SmartContract/Native/Tokens/NeoToken.cs

@@ -204,7 +204,7 @@ private StackItem GetRegisteredValidators(ApplicationEngine engine, VMArray args
             byte[] prefix_key = StorageKey.CreateSearchPrefix(Hash, new[] { Prefix_Validator });
             return snapshot.Storages.Find(prefix_key).Select(p =>
             (
-                p.Key.Key.Skip(1).ToArray().AsSerializable<ECPoint>(),
+                p.Key.Key.AsSerializable<ECPoint>(1),
                 ValidatorState.FromByteArray(p.Value.Value).Votes
             ));
         }

src/neo/UInt160.cs

@@ -81,7 +81,9 @@ public unsafe bool Equals(UInt160 other)
                 value = value.Substring(2);
             if (value.Length != Length * 2)
                 throw new FormatException();
-            return new UInt160(value.HexToBytes().Reverse());
+            byte[] data = value.HexToBytes();
+            Array.Reverse(data);
+            return new UInt160(data);
         }
 
         /// <summary>
@@ -109,7 +111,8 @@ public static bool TryParse(string s, out UInt160 result)
                     result = null;
                     return false;
                 }
-            result = new UInt160(data.Reverse());
+            Array.Reverse(data);
+            result = new UInt160(data);
             return true;
         }
 

src/neo/UInt256.cs

@@ -82,7 +82,9 @@ public unsafe bool Equals(UInt256 other)
                 s = s.Substring(2);
             if (s.Length != Length * 2)
                 throw new FormatException();
-            return new UInt256(s.HexToBytes().Reverse());
+            byte[] data = s.HexToBytes();
+            Array.Reverse(data);
+            return new UInt256(data);
         }
 
         /// <summary>
@@ -110,7 +112,8 @@ public static bool TryParse(string s, out UInt256 result)
                     result = null;
                     return false;
                 }
-            result = new UInt256(data.Reverse());
+            Array.Reverse(data);
+            result = new UInt256(data);
             return true;
         }
 

src/neo/UIntBase.cs

@@ -61,7 +61,7 @@ public bool Equals(UIntBase other)
                 return true;
             if (data_bytes.Length != other.data_bytes.Length)
                 return false;
-            return Helper.MemoryEquals(data_bytes, other.data_bytes);
+            return MemoryExtensions.SequenceEqual<byte>(data_bytes, other.data_bytes);
         }
 
         /// <summary>
@@ -122,7 +122,7 @@ public byte[] ToArray()
         /// </summary>
         public override string ToString()
         {
-            return "0x" + data_bytes.Reverse().ToHexString();
+            return "0x" + data_bytes.ToHexString(reverse: true);
         }
 
         /// <summary>

src/neo/Wallets/Helper.cs

@@ -2,15 +2,14 @@
 using Neo.Network.P2P;
 using Neo.Network.P2P.Payloads;
 using System;
-using System.Linq;
 
 namespace Neo.Wallets
 {
     public static class Helper
     {
         public static byte[] Sign(this IVerifiable verifiable, KeyPair key)
         {
-            return Crypto.Default.Sign(verifiable.GetHashData(), key.PrivateKey, key.PublicKey.EncodePoint(false).Skip(1).ToArray());
+            return Crypto.Default.Sign(verifiable.GetHashData(), key.PrivateKey, key.PublicKey.EncodePoint(false)[1..]);
         }
 
         public static string ToAddress(this UInt160 scriptHash)
@@ -28,7 +27,7 @@ public static UInt160 ToScriptHash(this string address)
                 throw new FormatException();
             if (data[0] != ProtocolSettings.Default.AddressVersion)
                 throw new FormatException();
-            return new UInt160(data.Skip(1).ToArray());
+            return new UInt160(data[1..]);
         }
     }
 }

src/neo/Wallets/KeyPair.cs

@@ -56,10 +56,10 @@ public string Export(string passphrase, int N = 16384, int r = 8, int p = 8)
         {
             UInt160 script_hash = Contract.CreateSignatureRedeemScript(PublicKey).ToScriptHash();
             string address = script_hash.ToAddress();
-            byte[] addresshash = Encoding.ASCII.GetBytes(address).Sha256().Sha256().Take(4).ToArray();
+            byte[] addresshash = Encoding.ASCII.GetBytes(address).Sha256().Sha256()[..4];
             byte[] derivedkey = SCrypt.DeriveKey(Encoding.UTF8.GetBytes(passphrase), addresshash, N, r, p, 64);
-            byte[] derivedhalf1 = derivedkey.Take(32).ToArray();
-            byte[] derivedhalf2 = derivedkey.Skip(32).ToArray();
+            byte[] derivedhalf1 = derivedkey[..32];
+            byte[] derivedhalf2 = derivedkey[32..];
             byte[] encryptedkey = XOR(PrivateKey, derivedhalf1).AES256Encrypt(derivedhalf2);
             byte[] buffer = new byte[39];
             buffer[0] = 0x01;

src/neo/Wallets/Wallet.cs

@@ -151,8 +151,8 @@ public static byte[] GetPrivateKeyFromNEP2(string nep2, string passphrase, int N
             byte[] datapassphrase = Encoding.UTF8.GetBytes(passphrase);
             byte[] derivedkey = SCrypt.DeriveKey(datapassphrase, addresshash, N, r, p, 64);
             Array.Clear(datapassphrase, 0, datapassphrase.Length);
-            byte[] derivedhalf1 = derivedkey.Take(32).ToArray();
-            byte[] derivedhalf2 = derivedkey.Skip(32).ToArray();
+            byte[] derivedhalf1 = derivedkey[..32];
+            byte[] derivedhalf2 = derivedkey[32..];
             Array.Clear(derivedkey, 0, derivedkey.Length);
             byte[] encryptedkey = new byte[32];
             Buffer.BlockCopy(data, 7, encryptedkey, 0, 32);
@@ -163,7 +163,7 @@ public static byte[] GetPrivateKeyFromNEP2(string nep2, string passphrase, int N
             ECPoint pubkey = Cryptography.ECC.ECCurve.Secp256r1.G * prikey;
             UInt160 script_hash = Contract.CreateSignatureRedeemScript(pubkey).ToScriptHash();
             string address = script_hash.ToAddress();
-            if (!Encoding.ASCII.GetBytes(address).Sha256().Sha256().Take(4).SequenceEqual(addresshash))
+            if (!Encoding.ASCII.GetBytes(address).Sha256().Sha256().AsSpan(0, 4).SequenceEqual(addresshash))
                 throw new FormatException();
             return prikey;
         }