Improve Embedding.ConvertToVectorOfFloats

src/Custom/Embeddings/Embedding.cs

@@ -1,5 +1,9 @@
 using System;
+using System.Buffers;
+using System.Buffers.Binary;
+using System.Buffers.Text;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 
 namespace OpenAI.Embeddings;
 
@@ -89,13 +93,43 @@ internal Embedding(int index, BinaryData embeddingProperty, InternalEmbeddingObj
  // CUSTOM: Implemented custom logic to transform from BinaryData to ReadOnlyMemory<float>.
  private ReadOnlyMemory<float> ConvertToVectorOfFloats(BinaryData binaryData)
  {
- string base64EncodedVector = binaryData.ToString();
- base64EncodedVector = base64EncodedVector.Substring(1, base64EncodedVector.Length - 2);
+ ReadOnlySpan<byte> base64 = binaryData.ToMemory().Span;
 
- byte[] bytes = Convert.FromBase64String(base64EncodedVector);
- float[] vector = new float[bytes.Length / sizeof(float)];
- Buffer.BlockCopy(bytes, 0, vector, 0, bytes.Length);
+ // Remove quotes around base64 string.
+ if (base64.Length < 2 || base64[0] != (byte)'"' || base64[base64.Length - 1] != (byte)'"')
+ {
+ ThrowInvalidData();
+ }
+ base64 = base64.Slice(1, base64.Length - 2);
 
+ // Decode base64 string to bytes.
+ byte[] bytes = ArrayPool<byte>.Shared.Rent(Base64.GetMaxDecodedFromUtf8Length(base64.Length));
+ OperationStatus status = Base64.DecodeFromUtf8(base64, bytes.AsSpan(), out int bytesConsumed, out int bytesWritten);
+ if (status != OperationStatus.Done || bytesWritten % sizeof(float) != 0)
+ {
+ ThrowInvalidData();
+ }
+
+ // Interpret bytes as floats
+ float[] vector = new float[bytesWritten / sizeof(float)];
+ bytes.AsSpan(0, bytesWritten).CopyTo(MemoryMarshal.AsBytes(vector.AsSpan()));
+ if (!BitConverter.IsLittleEndian)
+ {
+ Span<int> ints = MemoryMarshal.Cast<float, int>(vector.AsSpan());
+#if NET8_0_OR_GREATER
+ BinaryPrimitives.ReverseEndianness(ints, ints);
+#else
+ for (int i = 0; i < ints.Length; i++)
+ {
+ ints[i] = BinaryPrimitives.ReverseEndianness(ints[i]);
+ }
+#endif
+ }
+
+ ArrayPool<byte>.Shared.Return(bytes);
  return new ReadOnlyMemory<float>(vector);
+
+ static void ThrowInvalidData() =>
+ throw new FormatException("The input is not a valid Base64 string of encoded floats.");
  }
 }