public static void EncodeApplicationTag(byte[] buf, ref int optr, BACnetEnums.BACNET_APPLICATION_TAG appTag, int value)
{
// http://www.bacnetwiki.com/wiki/index.php?title=Application_Tags
// establish the number of bytes required to encode the tag (i.e. length)
if (value > 15)
{
throw new Exception("Todo-encode values greater than one byte");
}
buf[optr++] = (byte)((int)appTag << 4 | 1);
buf[optr++] = (byte)(value & 0xff);
}
static public void InsertApplicationTag(byte[] buffer, ref int optr, BACnetEnums.BACNET_APPLICATION_TAG apptag, UInt32 value)
{
int saveOptr = optr++;
int length = 1;
if (value >= (1 << 24))
{
buffer[optr++] = (byte)((value >> 24) & 0xff);
length++;
}
if (value >= (1 << 16))
{
buffer[optr++] = (byte)((value >> 16) & 0xff);
length++;
}
if (value >= (1 << 8))
{
buffer[optr++] = (byte)((value >> 8) & 0xff);
length++;
}
buffer[optr++] = (byte)(value & 0xff);
buffer[saveOptr] = (byte)(((int)apptag << 4) | length);
}
// Create a new Application Tag
public BACnetObjectIdentifier(byte[] buf, ref int offset, BACnetEnums.TAG tagType, BACnetEnums.BACNET_APPLICATION_TAG appTag)
{
// is the next parameter even an application tag
if ((buf[offset] & 0x08) != 0x00)
{
// we have an unexpected context tag, sort this out
throw new Exception("m0515-Not a context tag");
// todo, now is there a way to avoid creating the object? Have to flag it at least...
//return;
}
if ((BACnetEnums.BACNET_APPLICATION_TAG)(((buf[offset] & 0xf0) >> 4)) != appTag)
{
// we have an unexpected context tag, sort this out
throw new Exception("m0519 - Unexpected application tag xxx , expecting " + appTag.ToString());
}
int contextTagSize = buf[offset] & 0x07;
offset++;
switch (appTag)
{
case BACnetEnums.BACNET_APPLICATION_TAG.BACNET_APPLICATION_TAG_OBJECT_ID:
if (contextTagSize != 4)
{
// we dont have a legal object ID!
throw new Exception("m0176-Illegal length");
//return;
}
this.objectType = (BACnetEnums.BACNET_OBJECT_TYPE)(((uint)buf[offset] << 2) | ((uint)buf[offset + 1] >> 6));
objectInstance = ((uint)buf[offset + 1] & 0x3f) << 16;
objectInstance |= ((uint)buf[offset + 2]) << 8;
objectInstance |= ((uint)buf[offset + 3]);
offset += 4;
return;
}
}
