os_cpu_c.c

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/*
*********************************************************************************************************
*                                               uC/OS-II
*                                        The Real-Time Kernel
*
*                           (c) Copyright 1999, Jean J. Labrosse, Weston, FL
*                                          All Rights Reserved
*
*                                         H8/300H Specific code
*                                            (ADVANCED mode)
*
* File         : OS_CPU_C.C
* By           : Bill Knight (GNU/ADVANCED port)
*                Jean J. Labrosse
*                Dr. Odd Arild Olsen (original uC/OS port)
* Port Version : V1.00
*********************************************************************************************************
*/

#include "INCLUDES.H"

/*
*********************************************************************************************************
*                                        INITIALIZE A TASK'S STACK
*
* Description: This function is called by either OSTaskCreate() or OSTaskCreateExt() to initialize the
*              stack frame of the task being created.  This function is highly processor specific.
*
* Arguments  : task          is a pointer to the task code
*
*              pdata         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_???).
*
* 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) The following simulates the stack for a function called by an exception.  The pointer
*                 to the function argument 'pdata' is placed in ER0 because the GNU compiler passes the 
*                 first argument of a function in this register.  If your compiler passes the first 
*                 argument on the stack, load it on the stack like in the original uC/OS.  
*              2) An INT16U pointer is used because the ???? model assumes a 16-bit wide stack.
*              3) The H8 is a BIG Endian processor
*********************************************************************************************************
*/

void *OSTaskStkInit (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT16U opt)
{
    INT32U *pstk32;


    opt       = opt;                         /* 'opt' is not used, prevent warning                     */
    pstk32    = (INT32U *)ptos;           	 /* Load stack pointer                                     */
                                             /* Simulate function call to task with argument           */
    *--pstk32 = (INT32U)pdata;               /*     If 'pdata' passed on stack                         */
    *--pstk32 = (INT32U)task;                /*     Return address                                     */
                                             /* Simulate interrupt stacking                            */
    *--pstk32 = (INT32U)task;                /* Advanced model: CCR w/ interrupts enabled & 24-bit PC  */
                                             /*     Simulate ISR Entry saving all registers            */
    *--pstk32 = (INT32U)0x66666666;          /*         ER6 = 0x66666666                               */
    *--pstk32 = (INT32U)0x55555555;          /*         ER5 = 0x55555555                               */
    *--pstk32 = (INT32U)0x44444444;          /*         ER4 = 0x44444444                               */
    *--pstk32 = (INT32U)0x33333333;          /*         ER3 = 0x33333333                               */
    *--pstk32 = (INT32U)0x22222222;          /*         ER2 = 0x22222222                               */
    *--pstk32 = (INT32U)0x11111111;          /*         ER1 = 0x11111111                               */
    *--pstk32 = (INT32U)pdata;               /*         ER0 = pdata                                    */
                                             /* 'pstk' now points at ER0 on stack                      */
    return ((void *)pstk32);                 /* Return pointer to new top-of-stack                     */
}

/*$PAGE*/
#if OS_CPU_HOOKS_EN
/*
*********************************************************************************************************
*                                          TASK CREATION HOOK
*
* Description: This function is called when a task is created.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being created.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
void OSTaskCreateHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}


/*
*********************************************************************************************************
*                                           TASK DELETION HOOK
*
* Description: This function is called when a task is deleted.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being deleted.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
void OSTaskDelHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}

/*
*********************************************************************************************************
*                                           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).
*********************************************************************************************************
*/
void OSTaskSwHook (void)
{
}

/*
*********************************************************************************************************
*                                           STATISTIC TASK HOOK
*
* Description: This function is called every second by uC/OS-II's statistics task.  This allows your 
*              application to add functionality to the statistics task.
*
* Arguments  : none
*********************************************************************************************************
*/
void OSTaskStatHook (void)
{
}

/*
*********************************************************************************************************
*                                               TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
void OSTimeTickHook (void)
{
}
#endif