private (int, ReadOnlyMemory <byte>) WriteMessageSize()
{
// Message size is written as protobuf base 128 varint.
// https://developers.google.com/protocol-buffers/docs/encoding#varints
int messageSize = _buffer.WrittenCount;
int varint = messageSize;
const int maxVarintSize = 5;
Span <byte> buff = stackalloc byte[maxVarintSize];
const int base128Mask = 0x7F;
const int highBit = 0x80;
int varintLen = 0;
while (true)
{
buff[varintLen] = (byte)(varint & base128Mask);
varint >>= 7;
if (varint == 0)
{
break;
}
buff[varintLen] |= highBit;
++varintLen;
}
++varintLen;
_buffer.Write(buff.Slice(0, varintLen));
return(messageSize, _buffer.WrittenMemory.Slice(messageSize, varintLen));
}
/// <inheritdoc/> void ICollection <T> .CopyTo(T[] array, int arrayIndex) => WrittenMemory.CopyTo(array.AsMemory(arrayIndex));
