Incorrect handling of baud rate values in RTPS

[drisebor]

Bug Report

This is a problem with the fast RTPS code.

For both client and agent code, baud rate values are generated from the program argument by converting the argument directly to a number. However in termios.h, the baud rate is encoded in a number of preset values, eg B57600. This affects the agent running on Ubuntu since the encoded value is different from the actual baud rate. As a result executing the following in Ubuntu terminal:
./micrortps_agent -b 57600 -d /dev/ttyUSB1
results in this failure message:
UART transport: device: /dev/ttyUSB1; baudrate: 57600; sleep: 1us; poll: 0ms

ERR SET BAUD /dev/ttyUSB1: 0 (22)
Close UART
EXITING...

With the problem corrected using an extra function to convert the baud rate to the encoded value, the behaviour shown in the terminal is:
UART transport: device: /dev/ttyUSB1; baudrate: 57600; sleep: 1us; poll: 0ms

no flush
sensor_combined publisher started

Note that there may be a separate problem with the code generation for the agent application. To obtain the above result, the agent software was generated using a modified msg/tools/generate_microRTPS_bridge.py script with the following diff:

53,54c53,59
<     if dir[0] != '/':
<         dir = root_path + "/" + dir
---
>     if len(dir)>0:
>         if dir[0] != '/':
>             dir = root_path + "/" + dir
>     else:
>         dir = root_path
> 
>     print "dir returned from get_absolute_path",dir
66c71
< parser.add_argument("-t", "--topic-msg-dir", dest='msgdir', type=str, nargs=1, help="Topics message dir, by default msg/", default="msg")
---
> parser.add_argument("-t", "--topic-msg-dir", dest='msgdir', type=str, nargs=1, help="Topics message dir, by default msg/", default="")

[PX4BuildBot]

GitMate.io thinks possibly related issues are #4764 (VTOL: Nasty Yaw problem after back trans. in ALT and POS), and #7675 (Some questions about “mc_att_control” hope to get help).

[LorenzMeier]

@drisebor Thanks! Would you mind sending a pull request with the proposed fixes?
https://dev.px4.io/en/contribute/#source-code-management