public static int ComputeEncodedBytes(ReadOnlySpan <char> utf16source)
{
Span <byte> utf8Destination;
unsafe {
byte *buffer = stackalloc byte[32];
utf8Destination = new Span <byte>(buffer, 32);
}
var utf16Bytes = utf16source.Cast <char, byte>();
int encodedBytes = 0;
for (int i = 0; i < utf16Bytes.Length; /* intentionally no increment */)
{
UnicodeCodePoint codePoint;
int consumedBytes;
if (Utf16LittleEndianEncoder.TryDecodeCodePoint(utf16Bytes.Slice(i), out codePoint, out consumedBytes))
{
i += consumedBytes;
int justEncodedBytes;
if (TryEncodeCodePoint(codePoint, utf8Destination, out justEncodedBytes))
{
encodedBytes += justEncodedBytes;
}
else
{
throw new NotImplementedException("this should resize the buffer");
}
}
else
{
throw new ArgumentOutOfRangeException(nameof(utf16source));
}
}
return(encodedBytes);
}
// TODO: this routime needs to be optimized.
public static bool TryEncode(ReadOnlySpan <char> utf16source, Span <byte> utf8Destination, out int encodedBytes)
{
var utf16Bytes = utf16source.Cast <char, byte>();
encodedBytes = 0;
for (int i = 0; i < utf16Bytes.Length; /* intentionally no increment */)
{
UnicodeCodePoint codePoint;
int consumedBytes;
if (Utf16LittleEndianEncoder.TryDecodeCodePoint(utf16Bytes.Slice(i), out codePoint, out consumedBytes))
{
i += consumedBytes;
int justEncodedBytes;
if (TryEncodeCodePoint(codePoint, utf8Destination, out justEncodedBytes))
{
utf8Destination = utf8Destination.Slice(justEncodedBytes);
encodedBytes += justEncodedBytes;
}
else
{
return(false);
}
}
else
{
throw new ArgumentOutOfRangeException(nameof(utf16source));
}
}
return(true);
}
