The Linux kernal is written in C (with GNU extentions) with *some* assembly code.

When looking at Scheduling there are lots of ways you can do it.

• First in first out (FIFO)
• Priority scheduling
• Shortest remaining time first
• Fixed priority pre-emptive scheduling
• Round-robin scheduling
• Multilevel queue scheduling
• Work-conserving schedulers

I suggest that you start with a simple FIFO task scheduler using a queue as a starting point. There is no reason that you can't do that entirely in C.

If you haven't already - Before making a task scheduler I would suggest that you start with learning about abstract data types in C first. Things like:

• Single-linked Lists
• Double-linked Lists
• Circular Lists
• Stacks
• Queues
• Priority Queues
• Deques
• Heterogeneous Structures and Object Trees
• Binary Trees
• Balanced Binary Trees
• Tries
• Hash Tables
• Sparse Matrix

... And write at least one program for each one.

Is this advice for assembly language?

I have downloaded FreeRTOS sample codes which run on PC. Just trying to understand the sample code

 

Is this advice for assembly language?

No, this was advice for C.