两个习题
-
先了解下CPU上函数调用的过程:
- 一个程序取得函数地址，先保护现场将局部变量及参数压栈，再将调用函数的参数压栈，然后跳转到函数位置，将参数出栈，执行代码，结束后返回到调用位置，再恢复现场。但在MCU中，为了效率与其通常的业务场景可能并不这么做，对于局部变量不会专门保存与恢复。
- 在多任务系统中，如果多个任务并发的调用一个函数，可能会产生干扰，简单的说是线程不安全。
如果一个函数被多个任务并发的调用而不产生干扰(线程安全)，就是可重入函数。 - 参考窥探Keil4 C51的函数调用
-
各个任务用来存储各自任务堆栈内容的空间是任务堆栈；各个任务在运行时使用的堆栈是系统堆栈。
在任务切换时，系统堆栈的内容要到重新保存到被中止任务的堆栈空间，要运行的任务的堆栈内存复制到系统堆栈上来。
任务没有在运行时任务堆栈空间的内容只是备份，所以是那些内容是任务堆栈映像。
移植记录
先使用Keil4 建立一个工程 ucosii_c51,建立两组User与uCOS-II，在User中加入main.c,在uCOS-II中加入uCOS-II的源码
的uCOS-II的目录下新建 os_cfg.h,os_cpu.h,app_cfg.h 三个头文件，把os_cfg_r.h的内容先复制到os_cfg.h中来
然后修改os_cfg.h来对uCOS-II系统进行裁减，先做到最小配置
#ifndef __OS_CFG_H__
#define __OS_CFG_H__/* ---------------------- MISCELLANEOUS ----------------------- */
#define OS_APP_HOOKS_EN 0u /* Application-defined hooks are called from the uC/OS-II hooks */
#define OS_ARG_CHK_EN 0u /* Enable (1) or Disable (0) argument checking */
#define OS_CPU_HOOKS_EN 0u /* uC/OS-II hooks are found in the processor port files */#define OS_DEBUG_EN 0u /* Enable(1) debug variables */#define OS_EVENT_MULTI_EN 1u /* Include code for OSEventPendMulti() */
#define OS_EVENT_NAME_EN 0u /* Enable names for Sem, Mutex, Mbox and Q */#define OS_LOWEST_PRIO 20u /* Defines the lowest priority that can be assigned ... *//* ... MUST NEVER be higher than 254! */#define OS_MAX_EVENTS 10u /* Max. number of event control blocks in your application */
#define OS_MAX_FLAGS 5u /* Max. number of Event Flag Groups in your application */
#define OS_MAX_MEM_PART 5u /* Max. number of memory partitions */
#define OS_MAX_QS 4u /* Max. number of queue control blocks in your application */
#define OS_MAX_TASKS 20u /* Max. number of tasks in your application, MUST be >= 2 */#define OS_SCHED_LOCK_EN 1u /* Include code for OSSchedLock() and OSSchedUnlock() */#define OS_TICK_STEP_EN 1u /* Enable tick stepping feature for uC/OS-View */
#define OS_TICKS_PER_SEC 100u /* Set the number of ticks in one second *//* --------------------- TASK STACK SIZE ---------------------- */
#define OS_TASK_TMR_STK_SIZE 128u /* Timer task stack size (# of OS_STK wide entries) */
#define OS_TASK_STAT_STK_SIZE 128u /* Statistics task stack size (# of OS_STK wide entries) */
#define OS_TASK_IDLE_STK_SIZE 128u /* Idle task stack size (# of OS_STK wide entries) *//* --------------------- TASK MANAGEMENT ---------------------- */
#define OS_TASK_CHANGE_PRIO_EN 0u /* Include code for OSTaskChangePrio() */
#define OS_TASK_CREATE_EN 1u /* Include code for OSTaskCreate() */
#define OS_TASK_CREATE_EXT_EN 0u /* Include code for OSTaskCreateExt() */
#define OS_TASK_DEL_EN 1u /* Include code for OSTaskDel() */
#define OS_TASK_NAME_EN 0u /* Enable task names */
#define OS_TASK_PROFILE_EN 1u /* Include variables in OS_TCB for profiling */
#define OS_TASK_QUERY_EN 1u /* Include code for OSTaskQuery() */
#define OS_TASK_REG_TBL_SIZE 1u /* Size of task variables array (#of INT32U entries) */
#define OS_TASK_STAT_EN 0u /* Enable (1) or Disable(0) the statistics task */
#define OS_TASK_STAT_STK_CHK_EN 1u /* Check task stacks from statistic task */
#define OS_TASK_SUSPEND_EN 1u /* Include code for OSTaskSuspend() and OSTaskResume() */
#define OS_TASK_SW_HOOK_EN 0u /* Include code for OSTaskSwHook() *//* ----------------------- EVENT FLAGS ------------------------ */
#define OS_FLAG_EN 0u /* Enable (1) or Disable (0) code generation for EVENT FLAGS */
#define OS_FLAG_ACCEPT_EN 1u /* Include code for OSFlagAccept() */
#define OS_FLAG_DEL_EN 1u /* Include code for OSFlagDel() */
#define OS_FLAG_NAME_EN 1u /* Enable names for event flag group */
#define OS_FLAG_QUERY_EN 1u /* Include code for OSFlagQuery() */
#define OS_FLAG_WAIT_CLR_EN 1u /* Include code for Wait on Clear EVENT FLAGS */
#define OS_FLAGS_NBITS 16u /* Size in #bits of OS_FLAGS data type (8, 16 or 32) *//* -------------------- MESSAGE MAILBOXES --------------------- */
#define OS_MBOX_EN 0u /* Enable (1) or Disable (0) code generation for MAILBOXES */
#define OS_MBOX_ACCEPT_EN 1u /* Include code for OSMboxAccept() */
#define OS_MBOX_DEL_EN 1u /* Include code for OSMboxDel() */
#define OS_MBOX_PEND_ABORT_EN 1u /* Include code for OSMboxPendAbort() */
#define OS_MBOX_POST_EN 1u /* Include code for OSMboxPost() */
#define OS_MBOX_POST_OPT_EN 1u /* Include code for OSMboxPostOpt() */
#define OS_MBOX_QUERY_EN 1u /* Include code for OSMboxQuery() *//* --------------------- MEMORY MANAGEMENT -------------------- */
#define OS_MEM_EN 0u /* Enable (1) or Disable (0) code generation for MEMORY MANAGER */
#define OS_MEM_NAME_EN 1u /* Enable memory partition names */
#define OS_MEM_QUERY_EN 1u /* Include code for OSMemQuery() *//* ---------------- MUTUAL EXCLUSION SEMAPHORES --------------- */
#define OS_MUTEX_EN 0u /* Enable (1) or Disable (0) code generation for MUTEX */
#define OS_MUTEX_ACCEPT_EN 1u /* Include code for OSMutexAccept() */
#define OS_MUTEX_DEL_EN 1u /* Include code for OSMutexDel() */
#define OS_MUTEX_QUERY_EN 1u /* Include code for OSMutexQuery() *//* ---------------------- MESSAGE QUEUES ---------------------- */
#define OS_Q_EN 0u /* Enable (1) or Disable (0) code generation for QUEUES */
#define OS_Q_ACCEPT_EN 1u /* Include code for OSQAccept() */
#define OS_Q_DEL_EN 1u /* Include code for OSQDel() */
#define OS_Q_FLUSH_EN 1u /* Include code for OSQFlush() */
#define OS_Q_PEND_ABORT_EN 1u /* Include code for OSQPendAbort() */
#define OS_Q_POST_EN 1u /* Include code for OSQPost() */
#define OS_Q_POST_FRONT_EN 1u /* Include code for OSQPostFront() */
#define OS_Q_POST_OPT_EN 1u /* Include code for OSQPostOpt() */
#define OS_Q_QUERY_EN 1u /* Include code for OSQQuery() *//* ------------------------ SEMAPHORES ------------------------ */
#define OS_SEM_EN 0u /* Enable (1) or Disable (0) code generation for SEMAPHORES */
#define OS_SEM_ACCEPT_EN 1u /* Include code for OSSemAccept() */
#define OS_SEM_DEL_EN 1u /* Include code for OSSemDel() */
#define OS_SEM_PEND_ABORT_EN 1u /* Include code for OSSemPendAbort() */
#define OS_SEM_QUERY_EN 1u /* Include code for OSSemQuery() */
#define OS_SEM_SET_EN 1u /* Include code for OSSemSet() *//* --------------------- TIME MANAGEMENT ---------------------- */
#define OS_TIME_DLY_HMSM_EN 1u /* Include code for OSTimeDlyHMSM() */
#define OS_TIME_DLY_RESUME_EN 1u /* Include code for OSTimeDlyResume() */
#define OS_TIME_GET_SET_EN 1u /* Include code for OSTimeGet() and OSTimeSet() */
#define OS_TIME_TICK_HOOK_EN 1u /* Include code for OSTimeTickHook() *//* --------------------- TIMER MANAGEMENT --------------------- */
#define OS_TMR_EN 0u /* Enable (1) or Disable (0) code generation for TIMERS */
#define OS_TMR_CFG_MAX 16u /* Maximum number of timers */
#define OS_TMR_CFG_NAME_EN 1u /* Determine timer names */
#define OS_TMR_CFG_WHEEL_SIZE 8u /* Size of timer wheel (#Spokes) */
#define OS_TMR_CFG_TICKS_PER_SEC 10u /* Rate at which timer management task runs (Hz) */#endif在os_cpu.h 中定义一些必要的数据类型及CPU相关配置
#ifndef __OS_CPU_H__
#define __OS_CPU_H__#include <REGX52.H>#define OS_STK_GROWTH 1u // 栈增长方向#define OS_CRITICAL_METHOD 0u // 不安全模式下#define OS_ENTER_CRITICAL() EA=0 // 关中断
#define OS_EXIT_CRITICAL() EA=1 // 开中断#define OS_TASK_SW() OSCtxSw()typedef unsigned char BOOLEAN;
typedef unsigned char INT8U;
typedef signed char INT8S;
typedef unsigned int INT16U;
typedef signed int INT16S;
typedef unsigned long int INT32U;
typedef signed long int INT32S;
typedef float FP32;
typedef double FP64;typedef INT8U OS_STK;#endif
添加一个源文件os_cpu_c.c
在里面实现任务堆栈初始化函数OSTaskStkInit
#include <ucos_ii.h>OS_STK *OSTaskStkInit(void (*task)(void*),void *p_arg,OS_STK *ptos,INT16U opt)
{(void)(task);(void)(p_arg);(void)(opt);return ptos;
}
添加三个源文件 os_cpu_asm_OSCtxSw.c，os_cpu_asm_OSIntCtxSw.c，os_cpu_asm_OSStartHighRdy.c分别来实现OSCtxSw，OSIntCtxSw，OSStartHighRdy；
在os_core.c 中可以看到以下代码
/*$PAGE*/
/*
*********************************************************************************************************
* START MULTITASKING
*
* Description: This function is used to start the multitasking process which lets uC/OS-II manages the
* task that you have created. Before you can call OSStart(), you MUST have called OSInit()
* and you MUST have created at least one task.
*
* Arguments : none
*
* Returns : none
*
* Note : OSStartHighRdy() MUST:
* a) Call OSTaskSwHook() then,
* b) Set OSRunning to OS_TRUE.
* c) Load the context of the task pointed to by OSTCBHighRdy.
* d_ Execute the task.
*********************************************************************************************************
*/void OSStart (void)
{if (OSRunning == OS_FALSE) {OS_SchedNew(); /* Find highest priority's task priority number */OSPrioCur = OSPrioHighRdy;OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy]; /* Point to highest priority task ready to run */OSTCBCur = OSTCBHighRdy;OSStartHighRdy(); /* Execute target specific code to start task */}
}
大致明白OSStartHighRdy 应该要实现什么
在os_cpu_asm_OSStartHighRdy.c写下
#include <REGX52.H>#ifndef OS_MASTER_FILE
#include <ucos_ii.h>
#endifvoid OSStartHighRdy(void){INT8U* stkptr;INT16U len;INT8U idx;INT8U dat;
#if OS_TASK_SW_HOOK_EN > 0uOSTaskSwHook();
#endifOSRunning = OS_TRUE;stkptr = (INT8U*)(OSTCBHighRdy->OSTCBStkPtr);len = *(INT16U*)stkptr;for(idx = 0u + sizeof(INT16U);idx < len; ++idx){dat = stkptr[idx];}
}
在keil里开启输出汇编
然后再SRC文件改一下，加入到工程中来
把任务堆栈映像到系统堆栈来，然后利用RETI指令跳转到任务函数中去。
现在编译一下，出现了 error C249: 'DATA': SEGMENT TOO LARGE，可以试着把编译内存模式改为大型
to be continue …