os_task.c

ucosII在c64x核上的移植

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                            TASK MANAGEMENT
*
*                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
*                                           All Rights Reserved
*
*                                                  V2.00
*
* File : OS_TASK.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include "ucos_ii.h"
#endif

/*
*********************************************************************************************************
*                                        LOCAL FUNCTION PROTOTYPES
*********************************************************************************************************
*/


static  void  OSDummy(void);

/*
*********************************************************************************************************
*                                            DUMMY FUNCTION
*
* Description: This function doesn't do anything.  It is called by OSTaskDel() to ensure that interrupts
*              are disabled immediately after they are enabled.
*
* Arguments  : none
*
* Returns    : none
*********************************************************************************************************
*/

static void  OSDummy (void)
{
}

/*$PAGE*/
/*
*********************************************************************************************************
*                                        CHANGE PRIORITY OF A TASK
*
* Description: This function allows you to change the priority of a task dynamically.  Note that the new
*              priority MUST be available.
*
* Arguments  : oldp     is the old priority
*
*              newp     is the new priority
*
* Returns    : OS_NO_ERR        is the call was successful
*              OS_PRIO_INVALID  if the priority you specify is higher that the maximum allowed 
*                               (i.e. >= OS_LOWEST_PRIO)
*              OS_PRIO_EXIST    if the new priority already exist.
*              OS_PRIO_ERR      there is no task with the specified OLD priority (i.e. the OLD task does
*                               not exist.
*********************************************************************************************************
*/

#if OS_TASK_CHANGE_PRIO_EN
INT8U OSTaskChangePrio (INT8U oldprio, INT8U newprio)
{

   return 0;
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                            CREATE A TASK
*
* Description: This function is used to have uC/OS-II manage the execution of a task.  Tasks can either
*              be created prior to the start of multitasking or by a running task.  A task cannot be
*              created by an ISR.
*
* Arguments  : task     is a pointer to the task's code
*
*              p_arg    is a pointer to an optional data area which can be used to pass parameters to
*                       the task when the task first executes.  Where the task is concerned it thinks
*                       it was invoked and passed the argument 'p_arg' as follows:
*
*                           void Task (void *p_arg)
*                           {
*                               for (;;) {
*                                   Task code;
*                               }
*                           }
*
*              ptos     is a pointer to the task's top of stack.  If the configuration constant
*                       OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
*                       memory to low memory).  'pstk' will thus point to the highest (valid) memory
*                       location of the stack.  If OS_STK_GROWTH is set to 0, 'pstk' will point to the
*                       lowest memory location of the stack and the stack will grow with increasing
*                       memory locations.
*
*              prio     is the task's priority.  A unique priority MUST be assigned to each task and the
*                       lower the number, the higher the priority.
*
* Returns    : OS_NO_ERR               if the function was successful.
*              OS_PRIO_EXIT            if the task priority already exist
*                                      (each task MUST have a unique priority).
*              OS_PRIO_INVALID         if the priority you specify is higher that the maximum allowed
*                                      (i.e. >= OS_LOWEST_PRIO)
*              OS_ERR_TASK_CREATE_ISR  if you tried to create a task from an ISR.
*********************************************************************************************************
*/

#if OS_TASK_CREATE_EN > 0
INT8U  OSTaskCreate (void (*task)(void *p_arg), void *p_arg, OS_STK *ptos, INT8U prio)
{
    OS_STK    *psp;
    INT8U      err;
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */
    OS_CPU_SR  cpu_sr = 0;
#endif



#if OS_ARG_CHK_EN > 0
    if (prio > OS_LOWEST_PRIO) {             /* Make sure priority is within allowable range           */
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (OSIntNesting > 0) {                  /* Make sure we don't create the task from within an ISR  */
        OS_EXIT_CRITICAL();
        return (OS_ERR_TASK_CREATE_ISR);
    }
    if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority  */
        OSTCBPrioTbl[prio] = (OS_TCB *)1;    /* Reserve the priority to prevent others from doing ...  */
                                             /* ... the same thing until task is created.              */
        OS_EXIT_CRITICAL();
        psp = OSTaskStkInit(task, p_arg, ptos, 0);              /* Initialize the task's stack         */
        err = OS_TCBInit(prio, psp, (OS_STK *)0, 0, 0, (void *)0, 0);
        if (err == OS_NO_ERR) {
            if (OSRunning == TRUE) {         /* Find highest priority task if multitasking has started */
                OS_Sched();
            }
        } else {
            OS_ENTER_CRITICAL();
            OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others                 */
            OS_EXIT_CRITICAL();
        }
        return (err);
    }
    OS_EXIT_CRITICAL();
    return (OS_PRIO_EXIST);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                     CREATE A TASK (Extended Version)
*
* Description: This function is used to have uC/OS-II manage the execution of a task.  Tasks can either
*              be created prior to the start of multitasking or by a running task.  A task cannot be
*              created by an ISR.  This function is similar to OSTaskCreate() except that it allows
*              additional information about a task to be specified.
*
* Arguments  : task      is a pointer to the task's code
*
*              p_arg     is a pointer to an optional data area which can be used to pass parameters to
*                        the task when the task first executes.  Where the task is concerned it thinks
*                        it was invoked and passed the argument 'p_arg' as follows:
*
*                            void Task (void *p_arg)
*                            {
*                                for (;;) {
*                                    Task code;
*                                }
*                            }
*
*              ptos      is a pointer to the task's top of stack.  If the configuration constant
*                        OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
*                        memory to low memory).  'ptos' will thus point to the highest (valid) memory
*                        location of the stack.  If OS_STK_GROWTH is set to 0, 'ptos' will point to the
*                        lowest memory location of the stack and the stack will grow with increasing
*                        memory locations.  'ptos' MUST point to a valid 'free' data item.
*
*              prio      is the task's priority.  A unique priority MUST be assigned to each task and the
*                        lower the number, the higher the priority.
*
*              id        is the task's ID (0..65535)
*
*              pbos      is a pointer to the task's bottom of stack.  If the configuration constant
*                        OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
*                        memory to low memory).  'pbos' will thus point to the LOWEST (valid) memory
*                        location of the stack.  If OS_STK_GROWTH is set to 0, 'pbos' will point to the
*                        HIGHEST memory location of the stack and the stack will grow with increasing
*                        memory locations.  'pbos' MUST point to a valid 'free' data item.
*
*              stk_size  is the size of the stack in number of elements.  If OS_STK is set to INT8U,
*                        'stk_size' corresponds to the number of bytes available.  If OS_STK is set to
*                        INT16U, 'stk_size' contains the number of 16-bit entries available.  Finally, if
*                        OS_STK is set to INT32U, 'stk_size' contains the number of 32-bit entries
*                        available on the stack.
*
*              pext      is a pointer to a user supplied memory location which is used as a TCB extension.
*                        For example, this user memory can hold the contents of floating-point registers
*                        during a context switch, the time each task takes to execute, the number of times
*                        the task has been switched-in, etc.
*
*              opt       contains additional information (or options) about the behavior of the task.  The
*                        LOWER 8-bits are reserved by uC/OS-II while the upper 8 bits can be application
*                        specific.  See OS_TASK_OPT_??? in uCOS-II.H.  Current choices are:
*
*                        OS_TASK_OPT_STK_CHK      Stack checking to be allowed for the task
*                        OS_TASK_OPT_STK_CLR      Clear the stack when the task is created
*                        OS_TASK_OPT_SAVE_FP      If the CPU has floating-point registers, save them
*                                                 during a context switch.
*
* Returns    : OS_NO_ERR               if the function was successful.
*              OS_PRIO_EXIT            if the task priority already exist
*                                      (each task MUST have a unique priority).
*              OS_PRIO_INVALID         if the priority you specify is higher that the maximum allowed
*                                      (i.e. > OS_LOWEST_PRIO)
*              OS_ERR_TASK_CREATE_ISR  if you tried to create a task from an ISR.
*********************************************************************************************************
*/
/*$PAGE*/
#if OS_TASK_CREATE_EXT_EN > 0
INT8U  OSTaskCreateExt (void   (*task)(void *p_arg),
                        void    *p_arg,
                        OS_STK  *ptos,
                        INT8U    prio,
                        INT16U   id,
                        OS_STK  *pbos,
                        INT32U   stk_size,
                        void    *pext,
                        INT16U   opt)
{
    OS_STK    *psp;
    INT8U      err;
#if OS_CRITICAL_METHOD == 3                  /* Allocate storage for CPU status register               */
    OS_CPU_SR  cpu_sr = 0;
#endif