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/* 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 */
}
}
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