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C/C++ Source code

#include "RTOS.h"

OS_STACKPTR int StackHP[128], StackLP[128];          /* Task stacks */
OS_TASK TCBHP, TCBLP;                        /* Task-control-blocks */

OS_U32 _VarA;
OS_U32 _VarB;

/*********************************************************************
*
*       _Restore
*       _Save
*
*  Function description
*    This function pair saves and restores an extended task context.
*    In this case, the extended task context consists of just a single
*    member, which is a global variable.
*/

typedef struct {
  OS_U32 VarA;
  OS_U32 VarB;
} CONTEXT_EXTENSION;

static void _Save(void * pStack) {
  CONTEXT_EXTENSION * p;
  p = ((CONTEXT_EXTENSION*)pStack) - (1 - OS_STACK_AT_BOTTOM);          // Create pointer to our structure
  //
  // Save all members of the structure
  //
  p->VarA = _VarA;
  p->VarB = _VarB;

}

static void _Restore(const void * pStack) {
  const CONTEXT_EXTENSION * p;
  p = ((const CONTEXT_EXTENSION *)pStack) - (1 - OS_STACK_AT_BOTTOM);   // Create pointer to our structure
  //
  // Restore all members of the structure
  //
  _VarA = p->VarA;
  _VarB = p->VarB;
}

/*********************************************************************
*
*       Global variable which holds the function pointers
*       to save and restore the task context.
*/
const OS_EXTEND_TASK_CONTEXT _SaveRestore = {
  _Save,
  _Restore
};

/********************************************************************/


/*********************************************************************
*
*       HPTask
*
*  Function description
*    During the execution of this function, the thread-specific
*    global variable has always the same value of 1.
*/
static void HPTask(void) {
  OS_ExtendTaskContext(&_SaveRestore);
  _VarA = 1;
  _VarB = 2;
  while (1) {
    OS_Delay (10);
  }
}

/*********************************************************************
*
*       LPTask
*
*  Function description
*    During the execution of this function, the thread-specific
*    global variable has always the same value of 2.
*/
static void LPTask(void) {
  OS_ExtendTaskContext(&_SaveRestore);
  _VarA = 3;
  _VarB = 4;
  while (1) {
    OS_Delay (50);
  }
}

/*********************************************************************
*
*       main
*/
int main(void) {
  OS_IncDI();                      /* Initially disable interrupts  */
  OS_InitKern();                   /* Initialize OS                 */
  OS_InitHW();                     /* Initialize Hardware for OS    */
  /* You need to create at least one task here !                    */
  OS_CREATETASK(&TCBHP, "HP Task", HPTask, 100, StackHP);
  OS_CREATETASK(&TCBLP, "LP Task", LPTask,  50, StackLP);
  OS_Start();                      /* Start multitasking            */
  return 0;
}