public static int ReadLengthPrefix(Stream source, bool expectHeader, PrefixStyle style, out int fieldNumber, out int bytesRead)
{
fieldNumber = 0;
switch (style)
{
case PrefixStyle.None:
bytesRead = 0;
return(2147483647);
case PrefixStyle.Base128:
{
bytesRead = 0;
uint num2;
int num;
if (!expectHeader)
{
num = ProtoReader.TryReadUInt32Variant(source, out num2);
bytesRead += num;
return((int)((bytesRead >= 0) ? num2 : 4294967295u));
}
num = ProtoReader.TryReadUInt32Variant(source, out num2);
bytesRead += num;
if (num <= 0)
{
bytesRead = 0;
return(-1);
}
if ((num2 & 7u) != 2u)
{
throw new InvalidOperationException();
}
fieldNumber = (int)(num2 >> 3);
num = ProtoReader.TryReadUInt32Variant(source, out num2);
bytesRead += num;
if (bytesRead == 0)
{
throw ProtoReader.EoF(null);
}
return((int)num2);
}
case PrefixStyle.Fixed32:
{
int num3 = source.ReadByte();
if (num3 < 0)
{
bytesRead = 0;
return(-1);
}
bytesRead = 4;
return(num3 | ProtoReader.ReadByteOrThrow(source) << 8 | ProtoReader.ReadByteOrThrow(source) << 16 | ProtoReader.ReadByteOrThrow(source) << 24);
}
case PrefixStyle.Fixed32BigEndian:
{
int num4 = source.ReadByte();
if (num4 < 0)
{
bytesRead = 0;
return(-1);
}
bytesRead = 4;
return(num4 << 24 | ProtoReader.ReadByteOrThrow(source) << 16 | ProtoReader.ReadByteOrThrow(source) << 8 | ProtoReader.ReadByteOrThrow(source));
}
default:
throw new ArgumentOutOfRangeException("style");
}
}
public static int DirectReadBigEndianInt32(Stream source)
{
return(ProtoReader.ReadByteOrThrow(source) << 24 | ProtoReader.ReadByteOrThrow(source) << 16 | ProtoReader.ReadByteOrThrow(source) << 8 | ProtoReader.ReadByteOrThrow(source));
}
