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Diffstat (limited to 'CAN-binder/libs/nanopb/examples/using_union_messages')
5 files changed, 0 insertions, 285 deletions
diff --git a/CAN-binder/libs/nanopb/examples/using_union_messages/Makefile b/CAN-binder/libs/nanopb/examples/using_union_messages/Makefile deleted file mode 100644 index 66396a0..0000000 --- a/CAN-binder/libs/nanopb/examples/using_union_messages/Makefile +++ /dev/null @@ -1,20 +0,0 @@ -# Include the nanopb provided Makefile rules -include ../../extra/nanopb.mk - -# Compiler flags to enable all warnings & debug info -CFLAGS = -ansi -Wall -Werror -g -O0 -CFLAGS += -I$(NANOPB_DIR) - -all: encode decode - ./encode 1 | ./decode - ./encode 2 | ./decode - ./encode 3 | ./decode - -.SUFFIXES: - -clean: - rm -f encode unionproto.pb.h unionproto.pb.c - -%: %.c unionproto.pb.c - $(CC) $(CFLAGS) -o $@ $^ $(NANOPB_CORE) - diff --git a/CAN-binder/libs/nanopb/examples/using_union_messages/README.txt b/CAN-binder/libs/nanopb/examples/using_union_messages/README.txt deleted file mode 100644 index 7a1e75d..0000000 --- a/CAN-binder/libs/nanopb/examples/using_union_messages/README.txt +++ /dev/null @@ -1,52 +0,0 @@ -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. - diff --git a/CAN-binder/libs/nanopb/examples/using_union_messages/decode.c b/CAN-binder/libs/nanopb/examples/using_union_messages/decode.c deleted file mode 100644 index b9f4af5..0000000 --- a/CAN-binder/libs/nanopb/examples/using_union_messages/decode.c +++ /dev/null @@ -1,96 +0,0 @@ -/* This program reads a message from stdin, detects its type and decodes it. - */ - -#include <stdio.h> -#include <string.h> -#include <stdlib.h> - -#include <pb_decode.h> -#include "unionproto.pb.h" - -/* This function reads manually the first tag from the stream and finds the - * corresponding message type. It doesn't yet decode the actual message. - * - * Returns a pointer to the MsgType_fields array, as an identifier for the - * message type. Returns null if the tag is of unknown type or an error occurs. - */ -const pb_field_t* decode_unionmessage_type(pb_istream_t *stream) -{ - pb_wire_type_t wire_type; - uint32_t tag; - bool eof; - - while (pb_decode_tag(stream, &wire_type, &tag, &eof)) - { - if (wire_type == PB_WT_STRING) - { - const pb_field_t *field; - for (field = UnionMessage_fields; field->tag != 0; field++) - { - if (field->tag == tag && (field->type & PB_LTYPE_SUBMESSAGE)) - { - /* Found our field. */ - return field->ptr; - } - } - } - - /* Wasn't our field.. */ - pb_skip_field(stream, wire_type); - } - - return NULL; -} - -bool decode_unionmessage_contents(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct) -{ - pb_istream_t substream; - bool status; - if (!pb_make_string_substream(stream, &substream)) - return false; - - status = pb_decode(&substream, fields, dest_struct); - pb_close_string_substream(stream, &substream); - return status; -} - -int main() -{ - /* Read the data into buffer */ - uint8_t buffer[512]; - size_t count = fread(buffer, 1, sizeof(buffer), stdin); - pb_istream_t stream = pb_istream_from_buffer(buffer, count); - - const pb_field_t *type = decode_unionmessage_type(&stream); - bool status = false; - - if (type == MsgType1_fields) - { - MsgType1 msg = {}; - status = decode_unionmessage_contents(&stream, MsgType1_fields, &msg); - printf("Got MsgType1: %d\n", msg.value); - } - else if (type == MsgType2_fields) - { - MsgType2 msg = {}; - status = decode_unionmessage_contents(&stream, MsgType2_fields, &msg); - printf("Got MsgType2: %s\n", msg.value ? "true" : "false"); - } - else if (type == MsgType3_fields) - { - MsgType3 msg = {}; - status = decode_unionmessage_contents(&stream, MsgType3_fields, &msg); - printf("Got MsgType3: %d %d\n", msg.value1, msg.value2); - } - - if (!status) - { - printf("Decode failed: %s\n", PB_GET_ERROR(&stream)); - return 1; - } - - return 0; -} - - - diff --git a/CAN-binder/libs/nanopb/examples/using_union_messages/encode.c b/CAN-binder/libs/nanopb/examples/using_union_messages/encode.c deleted file mode 100644 index e124bf9..0000000 --- a/CAN-binder/libs/nanopb/examples/using_union_messages/encode.c +++ /dev/null @@ -1,85 +0,0 @@ -/* This program takes a command line argument and encodes a message in - * one of MsgType1, MsgType2 or MsgType3. - */ - -#include <stdio.h> -#include <string.h> -#include <stdlib.h> - -#include <pb_encode.h> -#include "unionproto.pb.h" - -/* This function is the core of the union encoding process. It handles - * the top-level pb_field_t array manually, in order to encode a correct - * field tag before the message. The pointer to MsgType_fields array is - * used as an unique identifier for the message type. - */ -bool encode_unionmessage(pb_ostream_t *stream, const pb_field_t messagetype[], const void *message) -{ - const pb_field_t *field; - for (field = UnionMessage_fields; field->tag != 0; field++) - { - if (field->ptr == messagetype) - { - /* This is our field, encode the message using it. */ - if (!pb_encode_tag_for_field(stream, field)) - return false; - - return pb_encode_submessage(stream, messagetype, message); - } - } - - /* Didn't find the field for messagetype */ - return false; -} - -int main(int argc, char **argv) -{ - if (argc != 2) - { - fprintf(stderr, "Usage: %s (1|2|3)\n", argv[0]); - return 1; - } - - uint8_t buffer[512]; - pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer)); - - bool status = false; - int msgtype = atoi(argv[1]); - if (msgtype == 1) - { - /* Send message of type 1 */ - MsgType1 msg = {42}; - status = encode_unionmessage(&stream, MsgType1_fields, &msg); - } - else if (msgtype == 2) - { - /* Send message of type 2 */ - MsgType2 msg = {true}; - status = encode_unionmessage(&stream, MsgType2_fields, &msg); - } - else if (msgtype == 3) - { - /* Send message of type 3 */ - MsgType3 msg = {3, 1415}; - status = encode_unionmessage(&stream, MsgType3_fields, &msg); - } - else - { - fprintf(stderr, "Unknown message type: %d\n", msgtype); - return 2; - } - - if (!status) - { - fprintf(stderr, "Encoding failed!\n"); - return 3; - } - else - { - fwrite(buffer, 1, stream.bytes_written, stdout); - return 0; /* Success */ - } -} - - diff --git a/CAN-binder/libs/nanopb/examples/using_union_messages/unionproto.proto b/CAN-binder/libs/nanopb/examples/using_union_messages/unionproto.proto deleted file mode 100644 index 209df0d..0000000 --- a/CAN-binder/libs/nanopb/examples/using_union_messages/unionproto.proto +++ /dev/null @@ -1,32 +0,0 @@ -// This is an example of how to handle 'union' style messages -// with nanopb, without allocating memory for all the message types. -// -// There is no official type in Protocol Buffers for describing unions, -// but they are commonly implemented by filling out exactly one of -// several optional fields. - -syntax = "proto2"; - -message MsgType1 -{ - required int32 value = 1; -} - -message MsgType2 -{ - required bool value = 1; -} - -message MsgType3 -{ - required int32 value1 = 1; - required int32 value2 = 2; -} - -message UnionMessage -{ - optional MsgType1 msg1 = 1; - optional MsgType2 msg2 = 2; - optional MsgType3 msg3 = 3; -} - |