1 files changed, 133 insertions, 0 deletions
diff --git a/crypto/src/math/ec/rfc8032/Codec.cs b/crypto/src/math/ec/rfc8032/Codec.cs
new file mode 100644
index 000000000..3aacd12ab
--- /dev/null
+++ b/crypto/src/math/ec/rfc8032/Codec.cs
@@ -0,0 +1,133 @@
+using System;
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+using System.Buffers.Binary;
+#endif
+
+namespace Org.BouncyCastle.Math.EC.Rfc8032
+{
+    internal static class Codec
+    {
+        internal static uint Decode16(byte[] bs, int off)
+        {
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+            return BinaryPrimitives.ReadUInt16LittleEndian(bs.AsSpan(off));
+#else
+            uint n = bs[off];
+            n |= (uint)bs[++off] << 8;
+            return n;
+#endif
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static uint Decode16(ReadOnlySpan<byte> bs)
+        {
+            return BinaryPrimitives.ReadUInt16LittleEndian(bs);
+        }
+#endif
+
+        internal static uint Decode24(byte[] bs, int off)
+        {
+            uint n = bs[off];
+            n |= (uint)bs[++off] << 8;
+            n |= (uint)bs[++off] << 16;
+            return n;
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static uint Decode24(ReadOnlySpan<byte> bs)
+        {
+            uint n = bs[0];
+            n |= (uint)bs[1] << 8;
+            n |= (uint)bs[2] << 16;
+            return n;
+        }
+#endif
+
+        internal static uint Decode32(byte[] bs, int off)
+        {
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+            return BinaryPrimitives.ReadUInt32LittleEndian(bs.AsSpan(off));
+#else
+            uint n = bs[off];
+            n |= (uint)bs[++off] << 8;
+            n |= (uint)bs[++off] << 16;
+            n |= (uint)bs[++off] << 24;
+            return n;
+#endif
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static uint Decode32(ReadOnlySpan<byte> bs)
+        {
+            return BinaryPrimitives.ReadUInt32LittleEndian(bs);
+        }
+#endif
+
+        internal static void Decode32(byte[] bs, int bsOff, uint[] n, int nOff, int nLen)
+        {
+            for (int i = 0; i < nLen; ++i)
+            {
+                n[nOff + i] = Decode32(bs, bsOff + i * 4);
+            }
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static void Decode32(ReadOnlySpan<byte> bs, Span<uint> n)
+        {
+            for (int i = 0; i < n.Length; ++i)
+            {
+                n[i] = Decode32(bs[(i * 4)..]);
+            }
+        }
+#endif
+
+        internal static void Encode24(uint n, byte[] bs, int off)
+        {
+            bs[off] = (byte)(n);
+            bs[++off] = (byte)(n >> 8);
+            bs[++off] = (byte)(n >> 16);
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static void Encode24(uint n, Span<byte> bs)
+        {
+            bs[0] = (byte)(n);
+            bs[1] = (byte)(n >> 8);
+            bs[2] = (byte)(n >> 16);
+        }
+#endif
+
+        internal static void Encode32(uint n, byte[] bs, int off)
+        {
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+            BinaryPrimitives.WriteUInt32LittleEndian(bs.AsSpan(off), n);
+#else
+            bs[  off] = (byte)(n      );
+            bs[++off] = (byte)(n >>  8);
+            bs[++off] = (byte)(n >> 16);
+            bs[++off] = (byte)(n >> 24);
+#endif
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static void Encode32(uint n, Span<byte> bs)
+        {
+            BinaryPrimitives.WriteUInt32LittleEndian(bs, n);
+        }
+#endif
+
+        internal static void Encode56(ulong n, byte[] bs, int off)
+        {
+            Encode32((uint)n, bs, off);
+            Encode24((uint)(n >> 32), bs, off + 4);
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        internal static void Encode56(ulong n, Span<byte> bs)
+        {
+            Encode32((uint)n, bs);
+            Encode24((uint)(n >> 32), bs[4..]);
+        }
+#endif
+    }
+}