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Cc26xx fix read frame implementation

read_frame was misuing the packet length in the following ways:
- returning non-zero even if buf_len is too short for the packet
- truncating the length to buf_len if len is too long then using the
  truncated (i.e. wrong) length to index into the buffer
- memcpying too many bytes (used buf_len instead of real length)

This commit fixes all of this and adds some code to report
on packet length errors (to match with cc2538 driver).

- moved variable declaration to top of function in accordance with the
  Contiki style guide
- made function flatter, reduced nesting to improve readability

Fixed a race condition that could occur in read_frame because the
dataEntry is set to PENDING before we are finished reading from it.

Some finishing touch on the CBM retro targets.

Use a different LibreOffice ppa to install doxygen

Up to now we were using the LibreOffice 4.3 ppa (ppa:libreoffice/libreoffice-4-4) to install doxygen. The LibreOffice Packaging team appear to have removed this ppa, resulting in our doxygen build failing.

This changes the ppa we use to LibreOffice 4.4.x.

Changed RPL IPv6 NBR Callback Print Statement

Adjusted retro target clock to "new" DNS resolver.

The DNS resolver requires 1/4 sec clock resolution. The retro targets had a 1/2 sec clock resolution (optimized for the 1/2 sec TCP timer) resulting in DNS resolver timeouts being 0. Therefore the retro target clock resolution is now increased to 1/4 sec.

Implement TX of S/W ACKs with ContikiMAC

Fix default CoAP header block2 size

fix minor warning in cc2530-rf driver

[multicast] Do not forward every incoming TM ICMP

CC26xx - Enable RX_NOK on DEBUG builds

When a client sends a CoAP request with no block2 size,
the default one would be set to REST_MAX_CHUNK_SIZE.
However, this is not guaranteed to be a power of 2.
This can lead to clients receiving a bigger payload than expected as
part of the header, and ending up with duplicated content.
Setting the default to COAP_MAX_BLOCK_SIZE,
which is guaranteed to be a power of 2, fixes this.

Make ContikiMAC more configurable

Clarified that a newline is needed for the echo

Enabled the RX_NOK interrupt, if DEBUG or CC26XX_DEBUG_CRC are set
true, for the purpose of monitoring packets with bad CRC

The Trickle Multicast ICMP packet handler was not resetting uip_len to zero,
so all incoming TM ICMP packets were forwarded overloading the network.

CC26xx autoflush bad crc packets

Added missing charset abstraction.

Setting bAutoFlushCrc=1 so that the radio co-processor will
automatically drop packets with bad crc.

Allow the project / platform to provide values for CCA_SLEEP_TIME and LISTEN_TIME_AFTER_PACKET_DETECTED.

This is useful for sub-ghz operation.

This has been shamelessly stolen from the [Mountain Sensing project](https://github.com/feshie/contiki)

@heliosfa @kmartinez

Allow fixup to be repeated.

There are scenarios in which it is beneficial to search for an Etherne chip at several i/o locations. To do so the chip initialization is performed at several i/o locations until it succeeds. In order to allow for that operation model the i/o location fixup needs to be repeatable.

Note: This won't work with the RR-Net because the fixup bits overlap with the chip i/o bits.

turned on correlator in radio packet filter

Enabling this option seems to greatly improve transciever performance with
Contikimac. This seems to happen because Contikimac CCAs are much less likely
to detect false positives (thus screwing up the CCA sequence).

Allow to configure Telnetd idle timeout.

The default Telnetd idle timeout of 30 seconds seems somewhat short. Best to have it user-configurable (incl. the option to turn it off with an config value of 0).

Several retrocomputing config changes.

The change https://github.com/contiki-os/contiki/commit/c7b8bac0065f1292ecd1701fc7e2bbb121556f5e optimized memory usage and thus allowed to adjust the retro webbrowser configs for improved web page compatibility.

The .2mg image format contains a header which is missing from our file. So our file is rather a .po image.

I opted to not add the .2mg header as it is only necessary if the metadata it contains differs from the values "guessed" when using the "naked" .po image format. On the other hand there are image file consumers not understanding the .2mg image format.

Fix log messages of Travis tests in 12-rpl