os_cpu_c.c

嵌入式系统基础课件

/*
******************************************************************************
*			       uC/OS-II
*			 The Real-Time Kernel
*
*	(c) Copyright 1992-2001, Jean J. Labrosse, Weston, FL
*			 All Rights Reserved
*
*
*		       Intel x86 Specific code
*		  Protected Mode, Flat Memory Model
*
*			    DJGPP and NASM
*
* File         : OS_CPU_C.C
* By           : Dan Lewis
******************************************************************************
*/

#define  OS_CPU_GLOBALS

#include "libepc.h"
#include "os_cpu.h"
#include "os_cfg.h"
#include "ucos_ii.h"

ISR OldTickISR ;

/*
******************************************************************************
*		      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!
******************************************************************************
*/

OS_STK *OSTaskStkInit
(void (*task)(void *pd), void *pdata, OS_STK *ptos, INT16U opt)
{
    INT32U *stk;
    static BOOLEAN configured = FALSE ;

    if (!configured) {
        OS_ENTER_CRITICAL() ;
	OldTickISR = GetISR(IRQ2INT(IRQ_TICK)) ;
	SetISR(IRQ2INT(IRQ_TICK), OSTickISR) ;	/* use 1 msec ticks */
	SetISR(uCOS, OSCtxSw) ;	/* uCOS task switch: S/W INT	*/
	outportb(0x21, ~0x01) ;	/* Unmask the timer IRQ in PIC	*/
	OS_EXIT_CRITICAL() ;
	configured = TRUE ;
    }

    opt    = opt ;		/* 'opt' is not used, prevent warning	*/

    stk    = (INT32U *) ptos ;		/* Load stack pointer		*/

    /* Simulate call to function with arg */
    *--stk = (INT32U) pdata ;		/* Argument			*/
    *--stk = (INT32U) task ;		/* return address		*/

    /* Simulate INT instruction */
    *--stk = (INT32U) 0x00000200 ;	/* PSW = Interrupts enabled	*/
    *--stk = (INT32U) 0x0008 ;		/* Code selector		*/
    *--stk = (INT32U) task ;		/* return address		*/

    /* Simulate PUSHA instruction */
    *--stk = (INT32U) 0xAAAAAAAA ;	/* EAX				*/
    *--stk = (INT32U) 0xCCCCCCCC ;	/* ECX				*/
    *--stk = (INT32U) 0xDDDDDDDD ;	/* EDX				*/
    *--stk = (INT32U) 0xBBBBBBBB ;	/* EBX				*/
    *--stk = (INT32U) 0x00000000 ;	/* ESP				*/
    *--stk = (INT32U) 0x11111111 ;	/* EBP				*/
    *--stk = (INT32U) 0x22222222 ;	/* ESI				*/
    *--stk = (INT32U) 0x33333333 ;	/* EDI				*/

    return ((OS_STK *) stk) ;
}

#if OS_CPU_HOOKS_EN
/*
******************************************************************************
*			OS INITIALIZATION HOOK
*			     (BEGINNING)
*
* Description:	This function is called by OSInit() at the beginning
*		of OSInit().
*
* Arguments:	none
*
* Note(s):	1) Interrupts should be disabled during this call.
******************************************************************************
*/
#if OS_VERSION > 203
void OSInitHookBegin (void)
{
}
#endif

/*
******************************************************************************
*			OS INITIALIZATION HOOK
*				(END)
*
* Description:	This function is called by OSInit() at the end of OSInit().
*
* Arguments:	none
*
* Note(s):	1) Interrupts should be disabled during this call.
******************************************************************************
*/
#if OS_VERSION > 203
void OSInitHookEnd (void)
{
}
#endif


/*
******************************************************************************
*			  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)
{
}

/*
******************************************************************************
*			   OSTCBInit() HOOK
*
* Description:	This function is called by OSTCBInit() 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_VERSION > 203
void OSTCBInitHook (OS_TCB *ptcb)
{
    ptcb = ptcb ;	/* Prevent Compiler warning */
}
#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.
******************************************************************************
*/
void OSTimeTickHook (void)
{
}


/*
******************************************************************************
*			    IDLE TASK HOOK
*
* Description:	This function is called by the idle task.  This hook has
*		been added to allow you to do such things as STOP the CPU
*		to conserve power.
*
* Arguments:	none
*
* Note(s):	1) Interrupts are enabled during this call.
******************************************************************************
*/
#if OS_VERSION >= 251
void OSTaskIdleHook (void)
{
}
#endif
#endif