*
* Arguments  : task          is a pointer to the task code
*
*              p_arg         is a pointer to a user supplied data area that will be passed to the task
*                            when the task first executes.
*
*              ptos          is a pointer to the top of stack.  It is assumed that 'ptos' points to
*                            a 'free' entry on the task stack.  If OS_STK_GROWTH is set to 1 then
*                            'ptos' will contain the HIGHEST valid address of the stack.  Similarly, if
*                            OS_STK_GROWTH is set to 0, the 'ptos' will contains the LOWEST valid address
*                            of the stack.
*
*              opt           specifies options that can be used to alter the behavior of OSTaskStkInit().
*                            (see uCOS_II.H for OS_TASK_OPT_xxx).
*
* Returns    : Always returns the location of the new top-of-stack once the processor registers have
*              been placed on the stack in the proper order.
*
* Note(s)    : 1) Interrupts are enabled when your task starts executing.
*              2) All tasks run in Thread mode, using process stack.
*********************************************************************************************************
*/

OS_STK *OSTaskStkInit (void (*task)(void *p_arg), void *p_arg, OS_STK *ptos, INT16U opt)
{
    OS_STK *stk;


    (void)opt;                                   /* 'opt' is not used, prevent warning                 */
    stk       = ptos;                            /* Load stack pointer                                 */

                                                 /* Registers stacked as if auto-saved on exception    */
    *(stk)    = (INT32U)0x01000000L;             /* xPSR                                               */
    *(--stk)  = (INT32U)task;                    /* Entry Point                                        */
    *(--stk)  = (INT32U)0xFFFFFFFEL;             /* R14 (LR) (init value will cause fault if ever used)*/
    *(--stk)  = (INT32U)0x12121212L;             /* R12                                                */
    *(--stk)  = (INT32U)0x03030303L;             /* R3                                                 */
    *(--stk)  = (INT32U)0x02020202L;             /* R2                                                 */
    *(--stk)  = (INT32U)0x01010101L;             /* R1                                                 */
    *(--stk)  = (INT32U)p_arg;                   /* R0 : argument                                      */

                                                 /* Remaining registers saved on process stack         */
    *(--stk)  = (INT32U)0x11111111L;             /* R11                                                */
    *(--stk)  = (INT32U)0x10101010L;             /* R10                                                */
    *(--stk)  = (INT32U)0x09090909L;             /* R9                                                 */
    *(--stk)  = (INT32U)0x08080808L;             /* R8                                                 */
    *(--stk)  = (INT32U)0x07070707L;             /* R7                                                 */
    *(--stk)  = (INT32U)0x06060606L;             /* R6                                                 */
    *(--stk)  = (INT32U)0x05050505L;             /* R5                                                 */
    *(--stk)  = (INT32U)0x04040404L;             /* R4                                                 */

    return (stk);
}

/*
*********************************************************************************************************
*                                           TASK SWITCH HOOK
*
* Description: This function is called when a task switch is performed.  This allows you to perform other
*              operations during a context switch.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are disabled during this call.
*              2) It is assumed that the global pointer 'OSTCBHighRdy' points to the TCB of the task that
*                 will be 'switched in' (i.e. the highest priority task) and, 'OSTCBCur' points to the
*                 task being switched out (i.e. the preempted task).
*********************************************************************************************************
*/
#if (OS_CPU_HOOKS_EN > 0) && (OS_TASK_SW_HOOK_EN > 0)
void  OSTaskSwHook (void)
{
#if OS_APP_HOOKS_EN > 0
    App_TaskSwHook();
#endif
}
#endif

/*
*********************************************************************************************************
*                                           OS_TCBInit() HOOK
*
* Description: This function is called by OS_TCBInit() after setting up most of the TCB.
*
* Arguments  : ptcb    is a pointer to the TCB of the task being created.
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSTCBInitHook (OS_TCB *ptcb)
{
#if OS_APP_HOOKS_EN > 0
    App_TCBInitHook(ptcb);
#else
    (void)ptcb;                                  /* Prevent compiler warning                           */
#endif
}
#endif

/*
*********************************************************************************************************
*                                               TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if (OS_CPU_HOOKS_EN > 0) && (OS_TIME_TICK_HOOK_EN > 0)
void  OSTimeTickHook (void)
{
#if OS_APP_HOOKS_EN > 0
    App_TimeTickHook();
#endif

#if OS_TMR_EN > 0
    OSTmrCtr++;
    if (OSTmrCtr >= (OS_TICKS_PER_SEC / OS_TMR_CFG_TICKS_PER_SEC)) {
        OSTmrCtr = 0;
        OSTmrSignal();
    }
#endif
}
#endif

/*
*********************************************************************************************************
*                                         OS_CPU_SysTickHandler()
*
* Description: Handle the system tick (SysTick) interrupt, which is used to generate the uC/OS-II tick
*              interrupt.
*
* Arguments  : none.
*
* Note(s)    : 1) This function MUST be placed on entry 15 of the Cortex-M3 vector table.
*********************************************************************************************************
*/

void  OS_CPU_SysTickHandler (void)
{
    OS_CPU_SR  cpu_sr;


    OS_ENTER_CRITICAL();                         /* Tell uC/OS-II that we are starting an ISR          */
    OSIntNesting++;
    OS_EXIT_CRITICAL();

    OSTimeTick();                                /* Call uC/OS-II's OSTimeTick()                       */

    OSIntExit();                                 /* Tell uC/OS-II that we are leaving the ISR          */
}

/*
*********************************************************************************************************
*                                          OS_CPU_SysTickInit()
*
* Description: Initialize the SysTick.
*
* Arguments  : none.
*
* Note(s)    : 1) This function MUST be called after OSStart() & after processor initialization.
*********************************************************************************************************
*/

void  OS_CPU_SysTickInit (void)
{
    static  RCC_ClocksTypeDef  rcc_clocks;
    INT32U  cnts;

    RCC_GetClocksFreq(&rcc_clocks);

    cnts = (INT32U)rcc_clocks.HCLK_Frequency / OS_TICKS_PER_SEC;

    OS_CPU_CM3_NVIC_ST_RELOAD = (cnts - 1);
                                                 /* Set prio of SysTick handler to min prio.           */
    OS_CPU_CM3_NVIC_PRIO_ST   = OS_CPU_CM3_NVIC_PRIO_MIN;
                                                 /* Enable timer.                                      */
    OS_CPU_CM3_NVIC_ST_CTRL  |= OS_CPU_CM3_NVIC_ST_CTRL_CLK_SRC | OS_CPU_CM3_NVIC_ST_CTRL_ENABLE;
                                                 /* Enable timer interrupt.                            */
    OS_CPU_CM3_NVIC_ST_CTRL  |= OS_CPU_CM3_NVIC_ST_CTRL_INTEN;
}