?? os_task.c
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/*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* TASK MANAGEMENT
*
* (c) Copyright 1992-2003, Jean J. Labrosse, Weston, FL
* All Rights Reserved
*
* File : OS_TASK.C
* By : Jean J. Labrosse
* Version : V2.76
*********************************************************************************************************
*/
#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;
INT8U bitx;
INT8U bity;
INT8U y_old;
#if OS_CRITICAL_METHOD == 3
OS_CPU_SR cpu_sr; /* Storage for CPU status register */
cpu_sr = 0; /* Prevent compiler warning */
#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);
}
y = newprio >> 3; /* Yes, compute new TCB fields */
bity = OSMapTbl[y];
x = newprio & 0x07;
bitx = OSMapTbl[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) != 0x00) { /* If task is ready make it not */
OSRdyTbl[y_old] &= ~ptcb->OSTCBBitX;
if (OSRdyTbl[y_old] == 0x00) {
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 *pd), 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;
cpu_sr = 0; /* Prevent compiler warning */
#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 = (OS_STK *)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.
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