/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                            TASK MANAGEMENT
*
*                          (c) Copyright 1992-2005, Jean J. Labrosse, Weston, FL
*                                           All Rights Reserved
*
* File    : OS_TASK.C
* By      : Jean J. Labrosse
* Version : V2.80
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#endif

/*
*********************************************************************************************************
*                                        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.
*              OS_TASK_NOT_EXIST  if the task is assigned to a Mutex PIP.
*********************************************************************************************************
*/

#if OS_TASK_CHANGE_PRIO_EN > 0
INT8U  OSTaskChangePrio (INT8U oldprio, INT8U newprio)
{
#if OS_EVENT_EN
    OS_EVENT    *pevent;
#endif
    OS_TCB      *ptcb;
    INT8U        x;
    INT8U        y;
#if OS_LOWEST_PRIO <= 63
    INT8U        bitx;
    INT8U        bity;
#else
    INT16U       bitx;
    INT16U       bity;
#endif
    INT8U        y_old;
#if OS_CRITICAL_METHOD == 3
    OS_CPU_SR    cpu_sr = 0;                                    /* Storage for CPU status register     */
#endif



#if OS_ARG_CHK_EN > 0
    if (oldprio >= OS_LOWEST_PRIO) {
	    if (oldprio != OS_PRIO_SELF) {
            return (OS_PRIO_INVALID);
		}
	}
    if (newprio >= OS_LOWEST_PRIO) {
        return (OS_PRIO_INVALID);
    }
#endif
    OS_ENTER_CRITICAL();
    if (OSTCBPrioTbl[newprio] != (OS_TCB *)0) {                 /* New priority must not already exist */
        OS_EXIT_CRITICAL();
        return (OS_PRIO_EXIST);
    }
    if (oldprio == OS_PRIO_SELF) {                              /* See if changing self                */
        oldprio = OSTCBCur->OSTCBPrio;                          /* Yes, get priority                   */
    }
    ptcb = OSTCBPrioTbl[oldprio];
    if (ptcb == (OS_TCB *)0) {                                  /* Does task to change exist?          */
        OS_EXIT_CRITICAL();                                     /* No, can't change its priority!      */
        return (OS_PRIO_ERR);
    }
    if (ptcb == (OS_TCB *)1) {                                  /* Is task assigned to Mutex           */
        OS_EXIT_CRITICAL();                                     /* No, can't change its priority!      */
        return (OS_TASK_NOT_EXIST);
    }
#if OS_LOWEST_PRIO <= 63
    y                     = newprio >> 3;                       /* Yes, compute new TCB fields         */
    x                     = newprio & 0x07;
#else
    y                     = (newprio >> 4) & 0xFF;
    x                     =  newprio & 0x0F;
#endif

    bity                  = 1 << y;
    bitx                  = 1 << x;
    OSTCBPrioTbl[oldprio] = (OS_TCB *)0;                        /* Remove TCB from old priority        */
    OSTCBPrioTbl[newprio] = ptcb;                               /* Place pointer to TCB @ new priority */
    y_old                 = ptcb->OSTCBY;
    if ((OSRdyTbl[y_old] & ptcb->OSTCBBitX) != 0) {             /* If task is ready make it not        */
        OSRdyTbl[y_old] &= ~ptcb->OSTCBBitX;
        if (OSRdyTbl[y_old] == 0) {
            OSRdyGrp &= ~ptcb->OSTCBBitY;
        }
        OSRdyGrp    |= bity;                                    /* Make new priority ready to run      */
        OSRdyTbl[y] |= bitx;
#if OS_EVENT_EN
    } else {                                                    /* Task was not ready ...              */
        pevent = ptcb->OSTCBEventPtr;
        if (pevent != (OS_EVENT *)0) {                          /* ... remove from event wait list     */
            pevent->OSEventTbl[y_old] &= ~ptcb->OSTCBBitX;
            if (pevent->OSEventTbl[y_old] == 0) {
                pevent->OSEventGrp &= ~ptcb->OSTCBBitY;
            }
            pevent->OSEventGrp    |= bity;                      /* Add new priority to wait list       */
            pevent->OSEventTbl[y] |= bitx;
        }
#endif
    }
    ptcb->OSTCBPrio = newprio;                                  /* Set new task priority               */
    ptcb->OSTCBY    = y;
    ptcb->OSTCBX    = x;
    ptcb->OSTCBBitY = bity;
    ptcb->OSTCBBitX = bitx;
    OS_EXIT_CRITICAL();
    OS_Sched();                                                 /* Run highest priority task ready     */
    return (OS_NO_ERR);
}
#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