os_cpu_c.c

ucosz在2407上的移植代码

/*
*********************************************************************************************************
*                                               uC/OS-II
*                                         The Real-Time Kernel
*
*                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
*                                          All Rights Reserved
*
*
*                                       80x86/80x88 Specific code
*                                          LARGE MEMORY MODEL
*
* File : OS_CPU_C.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

#define  OS_CPU_GLOBALS
#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)    : Interrupts are enabled when your task starts executing. You can change this by setting the
*              PSW to 0x0002 instead.  In this case, interrupts would be disabled upon task startup.  The
*              application code would be responsible for enabling interrupts at the beginning of the task
*              code.  You will need to modify OSTaskIdle() and OSTaskStat() so that they enable 
*              interrupts.  Failure to do this will make your system crash!
*********************************************************************************************************
*/

void *OSTaskStkInit (void (*task)(void *pd), void *pdata, void *ptos, INT16U opt)
{
    INT16U *stk;

    opt    = opt;           /* 'opt' is not used, prevent warning */
    stk    = (INT16U *)ptos;/* Load stack pointer*/
	*stk++ =(INT16U)pdata;/*模仿调用程序时压参数入栈*/
	*stk++ =(INT16U)pdata;/* *stk++ =(INT16U)task;*/
		/*模仿调用程序时压返回地址入栈本来应存入task的地址，但因为
		在TMS3202XX中将返回地址压栈是程序本身的工作，因为返回地址
		在CPU本身的堆栈（8级）中，所以压了pdata两次，兼容于压程序
		返回地址的那种CPU，也因此在准备压入CPU堆栈的最后两个都是
		task的启始地址，一个用于中断返回，一个用于程序调用返回，
		不过后者没有用，因为任务是永远不能返回的*/
		/*stk+=15;*//*模仿中断时压寄存器和返回地址入栈*/
						/*pdata		for call	00*/
						/*pdata(task)for call	01*/
	
		stk++;			/*0 unuse*/		/*unuse		for i$$rest 02*/
		*stk++=0x21ec;	/*1 st1  */		/*st1		for i$$rest 03*/
		*stk++=0x2600;	/*2 st0  */		/*st0		for i$$rest 04*/
		*stk++=0;		/*3 ach  */		/*ach		for i$$rest 05*/
		*stk++=0xf;		/*4 acl  */		/*acl		for i$$rest 06*/
		*stk++=0;		/*5 sph  */		/*sph		for i$$rest 07*/
		*stk++=0;		/*6 spl  */		/*spl		for i$$rest 08*/
		*stk++=0;		/*7 t    */		/*t			for i$$rest 09*/
		*stk++=0;		/*8 ar0  */		/*ar0		for i$$rest 10*/
		*stk++=2;		/*9 ar2  */		/*ar2		for i$$rest 11*/
		*stk++=3;		/*10ar3  */		/*ar3		for i$$rest 12*/
		*stk++=4;		/*11ar4  */		/*ar4		for i$$rest 13*/
		*stk++=5;		/*12ar5  */		/*ar5		for i$$rest 14*/
		*stk++=6;		/*13ar6  */		/*ar6		for i$$rest 15*/
		*stk++=7;		/*14ar7  */		/*ar7		for i$$rest 16*/
	*stk++ =(INT16U)task;
		/*15		中断返回地址	for i$$rest 17*/		
	*stk++ =(INT16U)task;
		/*16		程序调用返回地址	for i$$rest 18*/		
	stk+=5;
		/*17-21		从堆栈中弹出的6个for i$$rest 19-23*/
		/*22		指针指向		24*/
	/*前面的注解中前面的标号指为i$$rest而压入堆栈的序号,后者指压入堆栈的序号*/
    return ((void *)stk);
}

/*$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