UC/OS-II kernel Architecture Analysis (4)-uC/OS-II Task Management

1. c executable code structure

(1) code segment. Text: The machine command that stores CPU execution. Generally,. text can be shared and read-only.

(2) Data Segment. Data:. rodata (constant data),. rwdata (initialized global variables, static variables ).

(3) uninitialized data segment. BSS: uninitialized global and static variables.

(4) stack. STACK: stores function parameters, local variables, and context During task switching.

(5) Heap. Heap: used for dynamic memory allocation.

2. Task Structure

In uC/OS-II, tasks are the basic unit of event operation and management. A uC/OS-II task contains at least program code, stacks, and TCB, and can selectively use dynamic memory space equivalent to heap. When running, tasks in the UC/OS-II are equivalent to executable code (units that can run independently ).

How to manage each part of the uC/OS-II task ???

3. Task Stack

• Task Stack data type: typedef unsigned short OS _stk
• Task Stack growth direction: # define OS _stk_growth 0/1
• Basic functions of the Task Stack :???

4. task control block (1) TCB description

It is mainly used to store the current attributes of a task. (Q: How do I run a task when it is scheduled for the first time ?)

(2) Main TCB members

• Job stack space location: ostcbstkptr, Ostcbstkbottom, Ostcbstksize;
• Task Communication and synchronization: ostcbeventptr, Ostcbmsg;
• Task event group flag: ostcbflagnode, Ostcbflagsrdy;
• Task waiting/Blocking: ostcbdly, Ostcbpendto;
• Current task status: ostcbstat;
• Task priority: ostcbprio;

(3) TCB global variables

• OS _ext OS _tcb ostcbtbl [OS _max_tasks + OS _n_sys_tasks];
• OS _ext OS _tcb ostcbpriotbl [OS _lowest_prio + 1];
• OS _ext OS _tcb * ostcbfreelist;
• OS _ext OS _tcb * ostcblist;
• OS _ext OS _tcb * ostcbhighrdy;
• OS _ext OS _tcb * ostcbcur;

5. Task status switching 6. task management functions

OS _task.c: 11 Functions

• Ostaskcreate ();
• Ostaskcreateext ();
• Ostaskdel ();
• Ostaskdelreq ();
• Ostaskchangeprio ();
• Ostasksuspend ();
• Ostaskresume ();
• Ostasknameget ();
• Ostasknameset ();
• Ostaskstkchk ();
• OS _taskstkclr ();
• Ostaskquery ();