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orb structs: add padding bytes to align the structs where necessary

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This is required for the logger, we just manually add the padding bytes
what would otherwise be done by the compiler. Additionally we reorder
the fields by type, so that padding is only necessary for nested types.
This commit is contained in:
Beat Küng
2016-05-05 14:10:23 +02:00
committed by Lorenz Meier
parent 7d4c4c0401
commit eabc43d78c
5 changed files with 152 additions and 106 deletions
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src/modules/logger/logger.cpp
+6 -28
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@@ -494,43 +494,21 @@ void Logger::run()
for (LoggerSubscription &sub : _subscriptions) {
/* each message consists of a header followed by an orb data object
* The size of the data object is given by orb_metadata.o_size
*/
size_t padded_msg_size = sub.metadata->o_size;
uint8_t orb_msg_padded[padded_msg_size];
size_t msg_size = sizeof(message_data_header_s) + sub.metadata->o_size;
//TODO: use sub.metadata->o_size_no_padding
uint8_t buffer[msg_size];
/* if this topic has been updated, copy the new data into the message buffer
* and write a message to the log
*/
//orb_check(sub.fd, &updated); // check whether a non-multi topic has been updated
/* this works for both single and multi-instances */
for (uint8_t instance = 0; instance < ORB_MULTI_MAX_INSTANCES; instance++) {
if (copy_if_updated_multi(sub.metadata, instance, &sub.fd[instance], &orb_msg_padded, &sub.time_tried_subscribe)) {
if (copy_if_updated_multi(sub.metadata, instance, &sub.fd[instance], buffer + sizeof(message_data_header_s),
&sub.time_tried_subscribe)) {
struct orb_output_buffer output_buffer = {};
uint8_t buffer[sizeof(message_data_header_s) + padded_msg_size];
output_buffer.data = &buffer;
output_buffer.next = sizeof(message_data_header_s);
sub.metadata->serialize(&orb_msg_padded, &output_buffer);
size_t msg_size = output_buffer.next;
//uint64_t timestamp;
//memcpy(&timestamp, buffer + sizeof(message_data_header_s), sizeof(timestamp));
//warnx("topic: %s, instance: %d, timestamp: %llu",
// sub.metadata->o_name, instance, timestamp);
/* copy the current topic data into the buffer after the header */
//orb_copy(sub.metadata, sub.fd, buffer + sizeof(message_data_header_s));
/* fill the message header struct in-place at the front of the buffer,
* accessing the unaligned (packed) structure properly
*/
message_data_header_s *header = reinterpret_cast<message_data_header_s *>(buffer);
header->msg_type = static_cast<uint8_t>(MessageType::DATA);
/* the ORB topic data object has 2 unused trailing bytes? */
//header->msg_size = static_cast<uint16_t>(msg_size - 3);
header->msg_size = msg_size;
header->msg_size = static_cast<uint16_t>(msg_size - 3);
header->msg_id = msg_id;
header->multi_id = 0x80 + instance; // Non multi, active