This commit moves the Settings Manager from the AVR codebase
into the Contiki core library. Any platform that implements
the Contiki EEPROM API can now use the Settings Manager's
key-value store for storing their persistent configuration info.
The Settings Manager is a EEPROM-based key-value store. Keys
are 16-bit integers and values may be up to 16,383 bytes long.
It is intended to be used to store configuration-related information,
like network settings, radio channels, etc.
* Robust data format which requires no initialization.
* Supports multiple values with the same key.
* Data can be appended without erasing EEPROM.
* Max size of settings data can be easily increased in the future,
as long as it doesn't overlap with application data.
The format was inspired by the [OLPC manufacturing data format][].
Since the beginning of EEPROM often contains application-specific
information, the best place to store settings is at the end of EEPROM
(the "top"). Because we are starting at the end of EEPROM, it makes
sense to grow the list of key-value pairs downward, toward the start of
EEPROM.
Each key-value pair is stored in memory in the following format:
Order | Size | Name | Description
--------:|---------:|--------------|-------------------------------
0 | 2 | `key` | 16-bit key
-2 | 1 | `size_check` | One's-complement of next byte
-3 | 1 or 2 | `size` | The size of `value`, in bytes
-4 or -5 | variable | `value` | Value associated with `key`
The end of the key-value pairs is denoted by the first invalid entry.
An invalid entry has any of the following attributes:
* The `size_check` byte doesn't match the one's compliment of the
`size` byte (or `size_low` byte).
* The key has a value of 0x0000.
[OLPC manufacturing data format]: http://wiki.laptop.org/go/Manufacturing_data
This is a general cleanup of things like code style issues and code structure of the STM32w port to make it more like the rest of Contiki is structured.
* add a few rimestats to keep track of sent and received acks
* made a number of configuration options possible to override (ack timing)
* added the logic for sending 802.15.4 link layer ack packets, despite not being able to guarentee the 802.15.4 MAC timing
* increased the number of sequence numbers to keep track of for duplicate filtering
Combined recent changes from darconeous...
- Refactor to decrease minimum code footprint.
- Added `RESOLV_CONF_SUPPORTS_RECORD_EXPIRATION`.
...with a few additional changes to reduce code size.
