Hi, getPayload() will return (void *), which means that it will point to array of memories. By casting it into structure pointer, it'll be easier to access the field inside the structure.
Here's a little illustration : (void *) AMSend.getPayload(&pkt) = 0x00 0x01 0x00 0x05 (BlinkToRadioMsg*) AMSend.getPayload(&pkt) = 0x0001 | 0x0005 (BlinkToRadioMsg*) AMSend.getPayload(&pkt) = nodeid | counter It's the concept of how C arranging the structures into plain array of memories (thus it's the basic of how to structure the plain array of memories into fields). I think K&R have explained it. Regards, -daniel -------- Original Message -------- > From: John Griessen <[EMAIL PROTECTED]> > What is the meaning of > (BlinkToRadioMsg*) (call AMSend.getPayload(&pkt)); > in the top line? Is this the syntax for coercing to type BlinkToRadioMsg*? > Where in the docs is this syntax defined? > > It's not like K&R C...where > you would declare *btrpkt to get a pointer you could use as btrpkt->nodeid > > > John Griessen > > Ecosensory _______________________________________________ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
