nikos chalikias
Testing [Andrew L] mbos RTOS for mbed Simply by copying code for main.cpp from mbos.h-comments
mbos Class Reference
A pre-emptive, mutlitasking real-time operating system for mbed applications. More...
#include <mbos.h>
Public Member Functions | |
| mbos (uint ntasks, uint ntimers=0, uint nresources=0) | |
| Create an mbos object. | |
| void | Start (uint idlestacksize=32) |
| Start mbos. | |
| void | CreateTask (uint taskid, uint priority, uint stacksz, void(*fun)(void)) |
| Create an mbos task. | |
| uint | GetTask (void) |
| Get the ID of the current task. | |
| void | SetPriority (uint priority) |
| Set the priority of the current task. | |
| uint | GetPriority (void) |
| Get the priority of the current task. | |
| void | WaitEvent (uint event) |
| Wait for an event or events. | |
| void | SetEvent (uint event, uint task) |
| Post an event or events to a task. | |
| uint | GetEvent (void) |
| Returns the event flag(s) which last caused the task to unblock. | |
| void | CreateTimer (uint timerid, uint taskid, uint event) |
| Create a mbos timer. | |
| void | SetTimer (uint timerid, uint time, uint reload=0) |
| Starts an mbos timer. | |
| void | RedirectTimer (uint timerid, uint taskid, uint event) |
| Redirects an mbos timer. | |
| void | ClearTimer (uint timerid) |
| Stops and clears an mbos timer. | |
| void | CreateResource (uint resourceid, uint priority) |
| Creates an mbos resource. | |
| uint | LockResource (uint resourceid) |
| Locks an mbos resource and temporarily allocates the resource's priority to the calling task. | |
| uint | TestResource (uint resourceid) |
| Tests whether a resource is locked or free, without changing its state. | |
| uint | FreeResource (uint resource) |
| Frees a resource Frees an mbos resource and restores the calling task's original priority. | |
Detailed Description
A pre-emptive, mutlitasking real-time operating system for mbed applications.
Allows the user to write their application in the form of independant tasks. The operating system manages a completely separate processor context for each task (processor registers and stack) and swaps between the tasks according to a simple scheduling algorithm.
Tasks are allocated a priority, and the scheduler ensures that the task that with the highest priority that is not waiting for an event, has control of the processor. If more than one task shares the highest priority, they will be run sequentially in round-robin fashion.
Each task may wait for one or more of up to 32 different events, each represented by one bit in the event flags word. Events may be posted by another task, by a mbos timer, or in response to some asynchronous event such as an peripheral interrupt.
mbos implements the SysTick timer to generate a System Tick every millisecond. Scheduling occurs once every Tick, or whenever a task blocks or an event is posted. The user may create one-shot or continuous timers to post events to tasks.
mbos implements a simple ceiling protocol resource locking mechanism To manage access to system resources. Tasks may take exclusive ownership of resources for a period.
A typical simple example with two tasks, and one timer, might look like this:
// mbos Blinky demonstration. // Task 1 toggles LED1 every second, under control of a timer. It then posts an event to // task 2 which flashed LED2 briefly. #include "mbed.h" #include "mbos.h" #define TASK1_ID 1 // Id for task 1 (idle task is 0) #define TASK1_PRIO 50 // priority for task 1 #define TASK1_STACK_SZ 32 // stack size for task 1 in words #define TASK2_ID 2 // Id for task 2 #define TASK2_PRIO 60 // priority for task 2 #define TASK2_STACK_SZ 32 // stack size for task 2 in words #define TIMER0_ID 0 // Id for timer 0 #define TIMER0_PERIOD 1000 // Time period in milliseconds #define TIMER0_EVENT 1 // Event flag (1 << 0) #define T1_TO_T2_EVENT 2 // Event flag (1 << 1) void task1(void); // task function prototypes void task2(void); DigitalOut led1(LED1); DigitalOut led2(LED2); mbos os(2, 1); // Instantiate mbos with 2 tasks & 1 timer int main(void) { // Configure tasks and timers os.CreateTask(TASK1_ID, TASK1_PRIO, TASK1_STACK_SZ, task1); os.CreateTask(TASK2_ID, TASK2_PRIO, TASK2_STACK_SZ, task2); os.CreateTimer(TIMER0_ID, TIMER0_EVENT, TASK1_ID); // Start mbos os.Start(); // never return! } void task1(void) { os.SetTimer(TIMER0_ID, TIMER0_PERIOD, TIMER0_PERIOD); while(1){ os.WaitEvent(TIMER0_EVENT); led1 = !led1; os.SetEvent(T1_TO_T2_EVENT, TASK2_ID); } } void task2(void) { while(1){ os.WaitEvent(T1_TO_T2_EVENT); led2 = 1; wait_ms(100); led2 = 0; } }
Definition at line 103 of file mbos.h.
Constructor & Destructor Documentation
| mbos | ( | uint | ntasks, |
| uint | ntimers = 0, |
||
| uint | nresources = 0 |
||
| ) |
Member Function Documentation
| void ClearTimer | ( | uint | timerid ) |
| void CreateResource | ( | uint | resourceid, |
| uint | priority | ||
| ) |
| void CreateTask | ( | uint | taskid, |
| uint | priority, | ||
| uint | stacksz, | ||
| void(*)(void) | fun | ||
| ) |
Create an mbos task.
Allocates and initialises data structures for the task.
- Parameters:
-
taskid Unique ID for the task. (1 .. ntasks). priority Priority (0 .. 99) of the task. Tasks may share the same priority. stacksize Size in words (>= 32) of the task's stack. fun Pointer to the task function. Function must be of type static void, and must return nothing.
| void CreateTimer | ( | uint | timerid, |
| uint | taskid, | ||
| uint | event | ||
| ) |
Create a mbos timer.
Allocates and initialises the data structures for the timer.
- Parameters:
-
timerid Unique ID for the timer (0 .. ntimers - 1). taskid The ID of the task to which the timer will post events. May not be the idle task. event The event flag(s) that the timer should post on timeout. May not be NULL.
| uint FreeResource | ( | uint | resource ) |
Frees a resource Frees an mbos resource and restores the calling task's original priority.
Does nothing if the resource is already free, if called from the idle task, or the resource was locked by a different task.
- Parameters:
-
resourceid The ID of the resource t free.
- Returns:
- Zero if the resource was freed successfully, or the ID of the task that is locking the resource, if not.
| uint GetEvent | ( | void | ) |
| uint GetPriority | ( | void | ) |
| uint GetTask | ( | void | ) |
| uint LockResource | ( | uint | resourceid ) |
Locks an mbos resource and temporarily allocates the resource's priority to the calling task.
Does nothing if the resource is already locked, or if called from the idle task.
- Parameters:
-
resourceid The ID of the resource to lock.
- Returns:
- Zero if the resource was locked successfully, or the ID of the task that is currently locking the resource, if not.
| void RedirectTimer | ( | uint | timerid, |
| uint | taskid, | ||
| uint | event | ||
| ) |
Redirects an mbos timer.
Changes the task and event associated with a timer. If the timer is running, the fun ction has no effect.
- Parameters:
-
timerid The ID of the timer. taskid The ID of the task to which the timer will post events. May not be the idle task. event The event flag(s) that the timer should post on timeout. May not be NULL.
| void SetEvent | ( | uint | event, |
| uint | task | ||
| ) |
Post an event or events to a task.
Posts the nominated event(s) to the specified task. Forces a context switch if the events are posted successfully. Does nothing if the task is not waiting, or is not waiting for the posted event.
- Parameters:
-
event Event flag(s) to post. task The ID of the task to which to post the event(s). May not be idle task.
| void SetPriority | ( | uint | priority ) |
| void SetTimer | ( | uint | timerid, |
| uint | time, | ||
| uint | reload = 0 |
||
| ) |
Starts an mbos timer.
If the reload time is zero or omitted, the timer will be reset once it has posted a single event, after time milliseconds. If the reload time is non-zero, this value will be loaded into the timer on time-out, and the timer will continue indefinitely. In this case the interval to the first event will be time, and the interval between subsequent events will be reloadtime.
- Parameters:
-
timerid The ID of the timer. time The period in milliseconds before the timer times out. reload The optional time to reload into the timer when it times out.
| void Start | ( | uint | idlestacksize = 32 ) |
Start mbos.
Optionally specify the size of the stack for a user-written idle task. All tasks, timers and resources must be created before calling Start.
- Parameters:
-
idlestacksize Size in words (>= 32) of the user-written idle task if present.
- Returns:
- Never returns
| uint TestResource | ( | uint | resourceid ) |
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