cnet's Application Programming Interface

NAME

CNET_write_direct - write a data frame directly to an indicated node

SYNOPSIS

#include <cnet.h> int CNET_write_direct(CnetAddr destaddr, const void *frame, size_t *length);

DESCRIPTION

CNET_write_direct requests that the indicated number of bytes, pointed to by frame, be written directly to the node indicated by destaddr. This function thus provides a reliable network/routing layer for asynchronous message passing, even if the source and destination nodes are not connected.

Messages transmitted using CNET_write_direct are considered to be transmitted on, and arrive on, link number 1. The special destination address ALLNODES may be used to transmit a message to all nodes except the sender. Regardless of the number of hops, propagation delays, and bandwidth, all frames sent via CNET_write_direct reach their destination in just 1000usecs.

On invocation, length must point to an integer indicating the number of bytes to be copied from frame. On return, the integer pointed to by length will now contain the number of bytes accepted by the Physical Layer.

RETURN VALUE

The value 0 is returned on success. On failure, the value -1 is returned, and the global variable cnet_errno is set to one of the following values to describe the error:

ER_BADARG

Either frame is a NULL pointer, or length is equal to zero.

ER_BADNODE

The value of destaddr refers to the current node.

ER_NOTREADY

The current node has not yet finished rebooting.

ER_TOOBUSY

An attempt has been made to write more than 1000 frames to the indicated destination before any of them have been read. This restriction is imposed to trap obvious errors in protocols.

SEE ALSO

CNET_write_physical, CNET_write_physical_reliable, and CNET_read_physical