+++ /dev/null
-Nanopb example "using_union_messages"
-=====================================
-
-Union messages is a common technique in Google Protocol Buffers used to
-represent a group of messages, only one of which is passed at a time.
-It is described in Google's documentation:
-https://developers.google.com/protocol-buffers/docs/techniques#union
-
-This directory contains an example on how to encode and decode union messages
-with minimal memory usage. Usually, nanopb would allocate space to store
-all of the possible messages at the same time, even though at most one of
-them will be used at a time.
-
-By using some of the lower level nanopb APIs, we can manually generate the
-top level message, so that we only need to allocate the one submessage that
-we actually want. Similarly when decoding, we can manually read the tag of
-the top level message, and only then allocate the memory for the submessage
-after we already know its type.
-
-
-Example usage
--------------
-
-Type `make` to run the example. It will build it and run commands like
-following:
-
-./encode 1 | ./decode
-Got MsgType1: 42
-./encode 2 | ./decode
-Got MsgType2: true
-./encode 3 | ./decode
-Got MsgType3: 3 1415
-
-This simply demonstrates that the "decode" program has correctly identified
-the type of the received message, and managed to decode it.
-
-
-Details of implementation
--------------------------
-
-unionproto.proto contains the protocol used in the example. It consists of
-three messages: MsgType1, MsgType2 and MsgType3, which are collected together
-into UnionMessage.
-
-encode.c takes one command line argument, which should be a number 1-3. It
-then fills in and encodes the corresponding message, and writes it to stdout.
-
-decode.c reads a UnionMessage from stdin. Then it calls the function
-decode_unionmessage_type() to determine the type of the message. After that,
-the corresponding message is decoded and the contents of it printed to the
-screen.
-
Code Review / apps / low-level-can-service.git / blobdiff