📄 os_mutex.lst
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C51 COMPILER V7.20 OS_MUTEX 04/25/2005 23:03:47 PAGE 1
C51 COMPILER V7.20, COMPILATION OF MODULE OS_MUTEX
OBJECT MODULE PLACED IN OS_MUTEX.obj
COMPILER INVOKED BY: D:\tools\Keil\C51\BIN\C51.EXE SOURCE\OS_MUTEX.C LARGE BROWSE INCDIR(D:\MY\empolder\uCOS-II\MCS-51\A
-T89C55WD\Keil 7_5\) DEBUG OBJECTEXTEND PRINT(.\OS_MUTEX.lst) OBJECT(OS_MUTEX.obj)
line level source
1 /*
2 *********************************************************************************************************
3 * uC/OS-II
4 * The Real-Time Kernel
5 * MUTUAL EXCLUSION SEMAPHORE MANAGEMENT
6 *
7 * (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
8 * All Rights Reserved
9 *
10 * File : OS_MUTEX.C
11 * By : Jean J. Labrosse
12 *********************************************************************************************************
13 */
14
15 #ifndef OS_MASTER_FILE
16 #include "includes.h"
17 #endif
18
19 /*
20 *********************************************************************************************************
21 * LOCAL CONSTANTS
22 *********************************************************************************************************
23 */
24
25 #define OS_MUTEX_KEEP_LOWER_8 0x00FF
26 #define OS_MUTEX_KEEP_UPPER_8 0xFF00
27
28 #define OS_MUTEX_AVAILABLE 0x00FF
29
30
31 #if OS_MUTEX_EN > 0
/*
*********************************************************************************************************
* ACCEPT MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function checks the mutual exclusion semaphore to see if a resource is available.
* Unlike OSMutexPend(), OSMutexAccept() does not suspend the calling task if the resource is
* not available or the event did not occur.
*
* Arguments : pevent is a pointer to the event control block
*
* err is a pointer to an error code which will be returned to your application:
* OS_NO_ERR if the call was successful.
* OS_ERR_EVENT_TYPE if 'pevent' is not a pointer to a mutex
* OS_ERR_PEVENT_NULL 'pevent' is a NULL pointer
* OS_ERR_PEND_ISR if you called this function from an ISR
*
* Returns : == 1 if the resource is available, the mutual exclusion semaphore is acquired
* == 0 a) if the resource is not available
* b) you didn't pass a pointer to a mutual exclusion semaphore
* c) you called this function from an ISR
*
* Warning(s) : This function CANNOT be called from an ISR because mutual exclusion semaphores are
* intended to be used by tasks only.
C51 COMPILER V7.20 OS_MUTEX 04/25/2005 23:03:47 PAGE 2
*********************************************************************************************************
*/
#if OS_MUTEX_ACCEPT_EN > 0
INT8U OSMutexAccept (OS_EVENT *pevent, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
if (OSIntNesting > 0) { /* Make sure it's not called from an ISR */
*err = OS_ERR_PEND_ISR;
return (0);
}
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return (0);
}
if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return (0);
}
#endif
OS_ENTER_CRITICAL(); /* Get value (0 or 1) of Mutex */
if ((pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE) {
pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8; /* Mask off LSByte (Acquire Mutex) */
pevent->OSEventCnt |= OSTCBCur->OSTCBPrio; /* Save current task priority in LSByte */
pevent->OSEventPtr = (void *)OSTCBCur; /* Link TCB of task owning Mutex */
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
return (1);
}
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
return (0);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function creates a mutual exclusion semaphore.
*
* Arguments : prio is the priority to use when accessing the mutual exclusion semaphore. In
* other words, when the semaphore is acquired and a higher priority task
* attempts to obtain the semaphore then the priority of the task owning the
* semaphore is raised to this priority. It is assumed that you will specify
* a priority that is LOWER in value than ANY of the tasks competing for the
* mutex.
*
* err is a pointer to an error code which will be returned to your application:
* OS_NO_ERR if the call was successful.
* OS_ERR_CREATE_ISR if you attempted to create a MUTEX from an ISR
* OS_PRIO_EXIST if a task at the priority inheritance priority
* already exist.
* OS_ERR_PEVENT_NULL No more event control blocks available.
* OS_PRIO_INVALID if the priority you specify is higher that the
* maximum allowed (i.e. > OS_LOWEST_PRIO)
C51 COMPILER V7.20 OS_MUTEX 04/25/2005 23:03:47 PAGE 3
*
* Returns : != (void *)0 is a pointer to the event control clock (OS_EVENT) associated with the
* created mutex.
* == (void *)0 if an error is detected.
*
* Note(s) : 1) The LEAST significant 8 bits of '.OSEventCnt' are used to hold the priority number
* of the task owning the mutex or 0xFF if no task owns the mutex.
* 2) The MOST significant 8 bits of '.OSEventCnt' are used to hold the priority number
* to use to reduce priority inversion.
*********************************************************************************************************
*/
OS_EVENT *OSMutexCreate (INT8U prio, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
OS_EVENT *pevent;
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_CREATE_ISR; /* ... can't CREATE mutex from an ISR */
return ((OS_EVENT *)0);
}
#if OS_ARG_CHK_EN > 0
if (prio >= OS_LOWEST_PRIO) { /* Validate PIP */
*err = OS_PRIO_INVALID;
return ((OS_EVENT *)0);
}
#endif
OS_ENTER_CRITICAL();
if (OSTCBPrioTbl[prio] != (OS_TCB *)0) { /* Mutex priority must not already exist */
OS_EXIT_CRITICAL(); /* Task already exist at priority ... */
*err = OS_PRIO_EXIST; /* ... inheritance priority */
return ((OS_EVENT *)0);
}
OSTCBPrioTbl[prio] = (OS_TCB *)1; /* Reserve the table entry */
pevent = OSEventFreeList; /* Get next free event control block */
if (pevent == (OS_EVENT *)0) { /* See if an ECB was available */
OSTCBPrioTbl[prio] = (OS_TCB *)0; /* No, Release the table entry */
OS_EXIT_CRITICAL();
*err = OS_ERR_PEVENT_NULL; /* No more event control blocks */
return (pevent);
}
OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr; /* Adjust the free list */
OS_EXIT_CRITICAL();
pevent->OSEventType = OS_EVENT_TYPE_MUTEX;
pevent->OSEventCnt = (prio << 8) | OS_MUTEX_AVAILABLE;/* Resource is available */
pevent->OSEventPtr = (void *)0; /* No task owning the mutex */
OS_EventWaitListInit(pevent);
*err = OS_NO_ERR;
return (pevent);
}
/*$PAGE*/
/*
*********************************************************************************************************
* DELETE A MUTEX
*
* Description: This function deletes a mutual exclusion semaphore and readies all tasks pending on the it.
*
* Arguments : pevent is a pointer to the event control block associated with the desired mutex.
C51 COMPILER V7.20 OS_MUTEX 04/25/2005 23:03:47 PAGE 4
*
* opt determines delete options as follows:
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