Quote:
Only the registered members can see the QUOTE Contents. Please Login OR Register.
Exactly. ingsvcd is outputting to gpspipe2, I'm reading from there, converting the date, writing correct NMEA sentence back to gpspipe. Obviously there are some rather complicated steps involved in this and there's also a checksum.
Quote:
Only the registered members can see the QUOTE Contents. Please Login OR Register.
Yes. It's called "LD_PRELOAD". Works only for binaries with dynamically linked libraries. Thankfully that's the case on TomTom. With LD_PRELOAD you can exchange the function in the binary with a function from your own library and then do whatever you want (e.g. change the file handle). This was new to me as well, just learned about it.
Quote:
Only the registered members can see the QUOTE Contents. Please Login OR Register.
True true. But computers sometimes are generous, aren't they? We might be lucky: the file name of the named pipe is indeed hardcoded into gltt, but that also means you can just change the string in the binary, as long as you don't change the length :)
Yes, initially I wanted to provide an example using LD_PRELOAD to overwrite the fdopen-function used by gltt and to change the output filename. Or even better, just intercept the data that gltt is writing into the named pipe and adjust it on the go. But I was too lazy now and the hex editor option seems sooo much simpler that I prefer to go this way first.
Quote:
Only the registered members can see the QUOTE Contents. Please Login OR Register.
While this is not easy, it's also not too difficult. It's actually quite a good task for someone to learn programming. However, Google also provides enough examples on how to do this. :) It was actually much more difficult (for me) to extract the date from the sentences and to transform it.
Next task: write a routine that stores the current date. If it detects next time that the current date is before the recorded date, it means we encountered the next WNRO event in 2038. Should I make it future proof or dodge the bullet like TomTom and just hope nobody is using any GL1 device anymore by 2038 :)
Oh, and maybe they will fail anyway because of the year 2038 problem...and I don't really wanna try that cause I'm afraid this might hardbrick my TomTom.
Quote:
Only the registered members can see the QUOTE Contents. Please Login OR Register.
I could do that, but like I said, it would take much more time, even though it might be a cleaner solution. For now I am going with the hex-editing option. I've prepared a fix, someone already tested it, and while there are satellites visible, it doesn't seem to get a fix. I suspect the NMEA sentences for $GPRMC are slightly different for the gltt binary, and I didn't really include much error checking in my original converter.
If you can help me out with some logged sentences from your GL1 device? Maybe some with, and some without satellite fix?