Mitsubishi Electric MSZ-FT25VGK / SH20D

[llozi]

I have a Mitsubishi Electric AC MSZ-FT25VGK which comes with a SH20D remote.
It seems not to be supported by IRremote8266.
I did run IRrecvdumpV2/3 and did a bit of further analysis with ToniA's Raw-IR-decoder-for-Arduino.
It turns out that the protocol is identical to the supported MitsubishiAC protocol with 23 bytes (144 bits) BUT preceded by the 5 bytes seemingly the Mitsubishi AC marker (23 CB 26 01 00) followed by a pause (GAP 8992).
ToniA's tool reports: PAUSE SPACE: 9014, HEADER MARK: 3490, HEADER SPACE: 1688, BIT MARK: 455, ZERO SPACE: 383, ONE SPACE: 1241.

auto_analyse_raw_data.py output:
kHdrMark: 3529
kHdrSpace: 1683
kBitMark: 489
kOneSpace: 1234
kZeroSpace: 381
kSpaceGap: 8992

I currently don't have the timing output of IRrecvDump at hand but I can easily provide it if useful.
I was able to implement decoding by simple modifications to the Raw-IR-decoder-for-Arduino code.
Implementing it for IRremoteESP8266 seems quite a task for me as it is not obvious where the needed changes should go.
Is there a chance you would do the implementation? Otherwise could you give me some hints on how to do it? Should I create a new class for this protocol? Or can it be easily added to IRMitsubishiAC class?
I would be happy about any help.

[llozi]

I now dived into it myself and have some working code.
I made a fork: https://github.com/llozi/IRremoteESP8266
where I added the new protocol "MITSUBISHI_AC_DBL" (for double signature, maybe we should find a better name)
to ir_Mitsubishi.cpp.

I subclassed IRMitsubishiAC and had more or less only to implement IRrecv::decodeMitsubishiACDbl and IRsend::sendMitsubishiACDbl.

Both decoding and sending is working with my AC and it's remote.

One thing I had to struggle with was that the matchGeneric(..) function returns bytes which have reversed bit order than what I wanted. I expected the MSBfirst parameter to change this but it makes no difference whether it is set to true or false. So I reverse the bit order "by hand" after reception.
Maybe matchGeneric(..) is not the right function to use in this case?
Anyhow, it works.

Can somebody review my code and eventually integrate it into IRremoteESP8266 lib?
That would be nice.
Sorry, I'm not an experienced c++ programmer, I only know about the basics.