Understanding Source Files and Debugging

Hi everyone, I’m relatively new to LinuxCNC—just a couple of months in—and I’m looking to customize it for my project. However, I’m struggling to understand how the source files are organized, which file serves what purpose, and how to work with them effectively.Specifically, I’m interested in:

• Motion Control: Which files are responsible for motion control, and how can I modify them?
• G-code Interpreter: Where can I find the G-code interpreter in the source, and how is it structured?

Is there any documentation that explains the structure and purpose of different source files? Also, any tips on how to debug or troubleshoot custom modifications would be really helpful.Looking forward to any guidance or resources you can share!Thanks in advance for your help. 

This may be of interest:
linuxcnc.org/docs/devel/html/code/code-notes.html

Thanks Aciera , i got some good understanding about its software architecture. But need some more depth concept and resources about how their handling files in motion control and G-code interpreter. what are file they using like wise.

Anybody know how or which file motion command are send to drive via ethercat . which file link ethercat and linuxcnc.