public virtual Task<int> ReadAsync(char[] buffer, int index, int count)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer), SR.ArgumentNull_Buffer);
}
if (index < 0 || count < 0)
{
throw new ArgumentOutOfRangeException((index < 0 ? nameof(index): nameof(count)), SR.ArgumentOutOfRange_NeedNonNegNum);
}
if (buffer.Length - index < count)
{
throw new ArgumentException(SR.Argument_InvalidOffLen);
}
return ReadAsyncInternal(buffer, index, count);
}