建立一个AVR的RTOS(5)—完善的协作式的内核
现在为上面的协作式内核添加一些OS中所必须的服务:
本文引用地址://m.amcfsurvey.com/article/201612/325276.htm1、挂起和重新运行任务
2、信号量(在必要时候,可以扩展成邮箱和信息队列)
3、延时
#include <avr/io.h>
#include
#include
unsigned char Stack[400];
register unsigned char OSRdyTbl asm("r2"); //任务运行就绪表
register unsigned char OSTaskRunningPrio asm("r3"); //正在运行的任务
#define OS_TASKS 3 //设定运行任务的数量
struct TaskCtrBlock
{
unsigned int OSTaskStackTop; //保存任务的堆栈顶
unsigned int OSWaitTick; //任务延时时钟
} TCB[OS_TASKS+1];
//防止被编译器占用
register unsigned char tempR4 asm("r4");
register unsigned char tempR5 asm("r5");
register unsigned char tempR6 asm("r6");
register unsigned char tempR7 asm("r7");
register unsigned char tempR8 asm("r8");
register unsigned char tempR9 asm("r9");
register unsigned char tempR10 asm("r10");
register unsigned char tempR11 asm("r11");
register unsigned char tempR12 asm("r12");
register unsigned char tempR13 asm("r13");
register unsigned char tempR14 asm("r14");
register unsigned char tempR15 asm("r15");
register unsigned char tempR16 asm("r16");
register unsigned char tempR16 asm("r17");
//建立任务
void OSTaskCreate(void (*Task)(void),unsigned char *Stack,unsigned char TaskID)
{
unsigned char i;
*Stack--=(unsigned int)Task>>8; //将任务的地址高位压入堆栈,
*Stack--=(unsigned int)Task; //将任务的地址低位压入堆栈,
*Stack--=0x00; //R1 __zero_reg__
*Stack--=0x00; //R0 __tmp_reg__
*Stack--=0x80;
//SREG在任务中,开启全局中断
for(i=0;i<14;i++) //在avr-libc中的FAQ中的What registers are used by the C compiler?
*Stack--=i; //描述了寄存器的作用
TCB[TaskID].OSTaskStackTop=(unsigned int)Stack; //将人工堆栈的栈顶,保存到堆栈的数组中
OSRdyTbl|=0x01<
}
//开始任务调度,从最低优先级的任务的开始
void OSStartTask()
{
OSTaskRunningPrio=OS_TASKS;
SP=TCB[OS_TASKS].OSTaskStackTop+17;
__asm__ __volatile__( "reti" "nt" );
}
//进行任务调度
void OSSched(void)
{
//根据中断时保存寄存器的次序入栈,模拟一次中断后,入栈的情况
__asm__ __volatile__("PUSH __zero_reg__ nt"); //R1
__asm__ __volatile__("PUSH __tmp_reg__ nt"); //R0
__asm__ __volatile__("IN __tmp_reg__,__SREG__ nt"); //保存状态寄存器SREG
__asm__ __volatile__("PUSH __tmp_reg__ nt");
__asm__ __volatile__("CLR __zero_reg__ nt"); //R0重新清零
__asm__ __volatile__("PUSH R18 nt");
__asm__ __volatile__("PUSH R19 nt");
__asm__ __volatile__("PUSH R20 nt");
__asm__ __volatile__("PUSH R21 nt");
__asm__ __volatile__("PUSH R22 nt");
__asm__ __volatile__("PUSH R23 nt");
__asm__ __volatile__("PUSH R24 nt");
__asm__ __volatile__("PUSH R25 nt");
__asm__ __volatile__("PUSH R26 nt");
__asm__ __volatile__("PUSH R27 nt");
__asm__ __volatile__("PUSH R30 nt");
__asm__ __volatile__("PUSH R31 nt");
__asm__ __volatile__("PUSH R28 nt"); //R28与R29用于建立在堆栈上的指针
__asm__ __volatile__("PUSH R29 nt"); //入栈完成
TCB[OSTaskRunningPrio].OSTaskStackTop=SP; //将正在运行的任务的堆栈底保存
unsigned char OSNextTaskID; //在现有堆栈上开设新的空间
for (OSNextTaskID = 0; //进行任务调度
OSNextTaskID < OS_TASKS && !(OSRdyTbl & (0x01<
OSNextTaskID++);
OSTaskRunningPrio = OSNextTaskID ;
cli(); //保护堆栈转换
SP=TCB[OSTaskRunningPrio].OSTaskStackTop;
sei();
//根据中断时的出栈次序
__asm__ __volatile__("POP R29 nt");
__asm__ __volatile__("POP R28 nt");
__asm__ __volatile__("POP R31 nt");
__asm__ __volatile__("POP R30 nt");
__asm__ __volatile__("POP R27 nt");
__asm__ __volatile__("POP R26 nt");
__asm__ __volatile__("POP R25 nt");
__asm__ __volatile__("POP R24 nt");
__asm__ __volatile__("POP R23 nt");
__asm__ __volatile__("POP R22 nt");
__asm__ __volatile__("POP R21 nt");
__asm__ __volatile__("POP R20 nt");
__asm__ __volatile__("POP R19 nt");
__asm__ __volatile__("POP R18 nt");
__asm__ __volatile__("POP __tmp_reg__ nt"); //SERG出栈并恢复
__asm__ __volatile__("OUT __SREG__,__tmp_reg__ nt"); //
__asm__ __volatile__("POP __tmp_reg__ nt"); //R0出栈
__asm__ __volatile__("POP __zero_reg__ nt"); //R1出栈
//中断时出栈完成
}
////////////////////////////////////////////任务处理
//挂起任务
void OSTaskSuspend(unsigned char prio)
{
TCB[prio].OSWaitTick=0;
OSRdyTbl &= ~(0x01<
if(OSTaskRunningPrio==prio) //当要挂起的任务为当前任务
OSSched(); //从新调度
}
//恢复任务可以让被OSTaskSuspend或OSTimeDly暂停的任务恢复
void OSTaskResume(unsigned char prio)
{
OSRdyTbl |= 0x01<
TCB[prio].OSWaitTick=0; //将时间计时设为0,到时
if(OSTaskRunningPrio>prio) //当要当前任务的优先级低于重置位的任务的优先级
OSSched(); //从新调度//从新调度
}
//任务延时
void OSTimeDly(unsigned int ticks)
{
if(ticks) //当延时有效
{
OSRdyTbl &= ~(0x01<
TCB[OSTaskRunningPrio].OSWaitTick=ticks;
OSSched(); //从新调度
}
}
//信号量
struct SemBlk
{
unsigned char OSEventType; //型号0,信号量独占型;1信号量共享型
unsigned char OSEventState; //状态0,不可用;1,可用
unsigned char OSTaskPendTbl; //等待信号量的任务列表
} Sem[10];
//初始化信号量
void OSSemCreat(unsigned char Index,unsigned char Type)
{
Sem[Index].OSEventType=Type; //型号0,信号量独占型;1信号量共享型
Sem[Index].OSTaskPendTbl=0;
Sem[Index].OSEventState=0;
}
//任务等待信号量,挂起
unsigned char OSTaskSemPend(unsigned char Index,unsigned int Timeout)
{
//unsigned char i=0;
if(Sem[Index].OSEventState) //信号量有效
{
if(Sem[Index].OSEventType==0) //如果为独占型
Sem[Index].OSEventState = 0x00; //信号量被独占,不可用
}
else
{ //加入信号的任务等待表
Sem[Index].OSTaskPendTbl |= 0x01<
OSRdyTbl &= ~(0x01<
TCB[OSTaskRunningPrio].OSWaitTick=Timeout; //如延时为0,刚无限等待
OSSched(); //从新调度
if(TCB[OSTaskRunningPrio].OSWaitTick==0) return 0;
}
return 1;
}
//发送一个信号量,可以从任务或中断发送
void OSSemPost(unsigned char Index)
{
if(Sem[Index].OSEventType) //当要求的信号量是共享型
{
Sem[Index].OSEventState=0x01; //使信号量有效
OSRdyTbl |=Sem [Index].OSTaskPendTbl; //使在等待该信号的所有任务就绪
Sem[Index].OSTaskPendTbl=0; //清空所有等待该信号的等待任务
}
else //当要求的信号量为独占型
{
unsigned char i;
for (i = 0; i < OS_TASKS && !(Sem[Index].OSTaskPendTbl & (0x01<
if(i < OS_TASKS) //如果有任务需要
{
Sem[Index].OSTaskPendTbl &= ~(0x01<
OSRdyTbl |= 0x01<
}
else
{
Sem[Index].OSEventState =1; //使信号量有效
}
}
}
//从任务发送一个信号量,并进行调度
void OSTaskSemPost(unsigned char Index)
{
OSSemPost(Index);
OSSched();
}
//清除一个信号量,只对共享型的有用。
//对于独占型的信号量,在任务占用后,就交得不可以用了。
void OSSemClean(unsigned char Index)
{
Sem[Index].OSEventState =0; //要求的信号量无效
}
void TCN0Init(void) //计时器0
{
TCCR0 = 0;
TCCR0 |= (1<
TIMSK |= (1<
TCNT0 = 100; //置计数起始值
}
SIGNAL(SIG_OVERFLOW0)
{
unsigned char i;
for(i=0;i
{
if(TCB[i].OSWaitTick)
{
TCB[i].OSWaitTick--;
if(TCB[i].OSWaitTick==0) //当任务时钟到时,必须是由定时器减时的才行
{
OSRdyTbl |= (0x01<
}
}
}
TCNT0=100;
}
void Task0()
{
unsigned int j=0;
while(1)
{
PORTB=j++;
OSTaskSuspend(1); //挂起任务1
OSTaskSemPost(0);
OSTimeDly(50);
OSTaskResume(1); //恢复任务1
OSSemClean(0);
OSTimeDly(50);
}
}
void Task1()
{
unsigned int j=0;
while(1)
{
PORTC=j++;
OSTimeDly(5);
}
}
void Task2()
{
unsigned int j=0;
while(1)
{
OSTaskSemPend(0,10);
PORTD=j++;
OSTimeDly(5);
}
}
void TaskScheduler()
{
while(1)
{
OSSched(); //反复进行调度
}
}
int main(void)
{
TCN0Init();
OSRdyTbl=0;
OSSemCreat(0,1); //将信号量设为共享型
OSTaskCreate(Task0,&Stack[99],0);
OSTaskCreate(Task1,&Stack[199],1);
OSTaskCreate(Task2,&Stack[299],2);
OSTaskCreate(TaskScheduler,&Stack[399],OS_TASKS);
OSStartTask();
}
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