System.IO.StreamReader.ReadToEndAsyncInternal C# (CSharp) Method

        private async Task<string> ReadToEndAsyncInternal()
        {
            // Call ReadBuffer, then pull data out of charBuffer.
            StringBuilder sb = new StringBuilder(CharLen_Prop - CharPos_Prop);
            do
            {
                int tmpCharPos = CharPos_Prop;
                sb.Append(CharBuffer_Prop, tmpCharPos, CharLen_Prop - tmpCharPos);
                CharPos_Prop = CharLen_Prop;  // We consumed these characters
                await ReadBufferAsync().ConfigureAwait(false);
            } while (CharLen_Prop > 0);

            return sb.ToString();
        }