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eed22a6f3c
* Added an optional "keep alive" mechanism whereby an idle network is periodically probed by dummy packets to maintain a recent quality metric when there is no traffic. * Bugfix in when new routing metrics should be advertised * Rewrote the ACK logic so that a queuebuf is not allocated for each ack, only for those acks generated by the sink node. * Updated the wrap-around logic for sequence numbers: when a sequence number wraps, it won't go back to 0. Instead, it wraps to 128. This allows us to understand when a node has rebooted: when its seqno is < 128, it has recently rebooted.
Contiki is an open source, highly portable, multi-tasking operating system for memory-constrained networked embedded systems written by Adam Dunkels at the Networked Embedded Systems group at the Swedish Institute of Computer Science. Contiki is designed for embedded systems with small amounts of memory. A typical Contiki configuration is 2 kilobytes of RAM and 40 kilobytes of ROM. Contiki consists of an event-driven kernel on top of which application programs are dynamically loaded and unloaded at runtime. Contiki processes use light-weight protothreads that provide a linear, thread-like programming style on top of the event-driven kernel. Contiki also supports per-process optional preemptive multi-threading, interprocess communication using message passing through events, as well as an optional GUI subsystem with either direct graphic support for locally connected terminals or networked virtual display with VNC or over Telnet. Contiki contains two communication stacks: uIP and Rime. uIP is a small RFC-compliant TCP/IP stack that makes it possible for Contiki to communicate over the Internet. Rime is a lightweight communication stack designed for low-power radios. Rime provides a wide range of communication primitives, from best-effort local area broadcast, to reliable multi-hop bulk data flooding. Contiki runs on a variety of platform ranging from embedded microcontrollers such as the MSP430 and the AVR to old homecomputers. Code footprint is on the order of kilobytes and memory usage can be configured to be as low as tens of bytes. Contiki is written in the C programming language and is freely available as open source under a BSD-style license. More information about Contiki can be found at the Contiki home page: http://www.sics.se/contiki/