第五篇：完善的协作式的内核
现在为上面的协作式内核增加一些OS中一切必要的服务：
1、挂起和从头运转使命
2、信号量(在必要时分，能够扩展成邮箱和信息行列)
3、延时
#include <avr/io.h>
#include
#include
unsigned char Stack[400];
register unsigned char OSRdyTbl asm(“r2”); //使命运转安排妥当表
register unsigned char OSTaskRunningPrio asm(“r3”); //正在运转的使命
#define OS_TASKS 3 //设定运转使命的数量
struct TaskCtrBlock
{
unsigned int OSTaskStackTop; //保存使命的仓库顶
unsigned int OSWaitTick; //使命延时时钟
} TCB[OS_TASKS+1];
//避免被编译器占用
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”);
//树立使命
void OSTaskCreate(void (*Task)(void),unsigned char *Stack,unsigned char TaskID)
{
unsigned char i;
*Stack–=(unsigned int)Task>>8; //将使命的地址高位压入仓库，
*Stack–=(unsigned int)Task; //将使命的地址低位压入仓库，
*Stack–=0x00; //R1 __zero_reg__
*Stack–=0x00; //R0 __tmp_reg__
*Stack–=0x80;
//SREG在使命中，敞开大局中止
for(i=0;i<14;i++) //在avr-libc中的FAQ中的What registers are used by the C compiler?
*Stack–=i; //描绘了寄存器的效果
TCB[TaskID].OSTaskStackTop=(unsigned int)Stack; //将人工仓库的栈顶，保存到仓库的数组中
OSRdyTbl|=0x01< }
//开端使命调度,从最低优先级的使命的开端
void OSStartTask()
{
OSTaskRunningPrio=OS_TASKS;
SP=TCB[OS_TASKS].OSTaskStackTop+17;
__asm__ __volatile__( “reti” “\n\t” );
}
//进行使命调度
void OSSched(void)
{
//依据中止时保存寄存器的次第入栈，模仿一次中止后，入栈的状况
__asm__ __volatile__(“PUSH __zero_reg__ \n\t”); //R1
__asm__ __volatile__(“PUSH __tmp_reg__ \n\t”); //R0
__asm__ __volatile__(“IN __tmp_reg__,__SREG__ \n\t”); //保存状况寄存器SREG
__asm__ __volatile__(“PUSH __tmp_reg__ \n\t”);
__asm__ __volatile__(“CLR __zero_reg__ \n\t”); //R0从头清零
__asm__ __volatile__(“PUSH R18 \n\t”);
__asm__ __volatile__(“PUSH R19 \n\t”);
__asm__ __volatile__(“PUSH R20 \n\t”);
__asm__ __volatile__(“PUSH R21 \n\t”);
__asm__ __volatile__(“PUSH R22 \n\t”);
__asm__ __volatile__(“PUSH R23 \n\t”);
__asm__ __volatile__(“PUSH R24 \n\t”);
__asm__ __volatile__(“PUSH R25 \n\t”);
__asm__ __volatile__(“PUSH R26 \n\t”);
__asm__ __volatile__(“PUSH R27 \n\t”);
__asm__ __volatile__(“PUSH R30 \n\t”);
__asm__ __volatile__(“PUSH R31 \n\t”);
__asm__ __volatile__(“PUSH R28 \n\t”); //R28与R29用于树立在仓库上的指针
__asm__ __volatile__(“PUSH R29 \n\t”); //入栈完结
TCB[OSTaskRunningPrio].OSTaskStackTop=SP; //将正在运转的使命的仓库底保存
unsigned char OSNextTaskID; //在现有仓库上开设新的空间
for (OSNextTaskID = 0; //进行使命调度
OSNextTaskID < OS_TASKS && !(OSRdyTbl & (0x01< OSNextTaskID++); OSTaskRunningPrio = OSNextTaskID ;
cli(); //维护仓库转化
SP=TCB[OSTaskRunningPrio].OSTaskStackTop;
sei();
//依据中止时的出栈次第
__asm__ __volatile__(“POP R29 \n\t”);
__asm__ __volatile__(“POP R28 \n\t”);
__asm__ __volatile__(“POP R31 \n\t”);
__asm__ __volatile__(“POP R30 \n\t”);
__asm__ __volatile__(“POP R27 \n\t”);
__asm__ __volatile__(“POP R26 \n\t”);
__asm__ __volatile__(“POP R25 \n\t”);
__asm__ __volatile__(“POP R24 \n\t”);
__asm__ __volatile__(“POP R23 \n\t”);
__asm__ __volatile__(“POP R22 \n\t”);
__asm__ __volatile__(“POP R21 \n\t”);
__asm__ __volatile__(“POP R20 \n\t”);
__asm__ __volatile__(“POP R19 \n\t”);
__asm__ __volatile__(“POP R18 \n\t”);
__asm__ __volatile__(“POP __tmp_reg__ \n\t”); //SERG出栈并康复
__asm__ __volatile__(“OUT __SREG__,__tmp_reg__ \n\t”); //
__asm__ __volatile__(“POP __tmp_reg__ \n\t”); //R0出栈
__asm__ __volatile__(“POP __zero_reg__ \n\t”); //R1出栈
//中止时出栈完结
}
////////////////////////////////////////////使命处理
//挂起使命
void OSTaskSuspend(unsigned char prio)
{
TCB[prio].OSWaitTick=0;
OSRdyTbl &= ~(0x01< if(OSTaskRunningPrio==prio) //当要挂起的使命为当前使命 OSSched(); //重新调度 }
//康复使命能够让被OSTaskSuspend或OSTimeDly暂停的使命康复
void OSTaskResume(unsigned char prio)
{
OSRdyTbl |= 0x01< TCB[prio].OSWaitTick=0; //将时刻计时设为0,届时 if(OSTaskRunningPrio>prio) //当要当前使命的优先级低于重置位的使命的优先级 OSSched(); //重新调度//重新调度 }
//使命延时
void OSTimeDly(unsigned int ticks)
{
if(ticks) //当延时有用
{
OSRdyTbl &= ~(0x01< TCB[OSTaskRunningPrio].OSWaitTick=ticks; OSSched(); //重新调度 } }
//信号量
struct SemBlk
{
unsigned char OSEventType; //类型0,信号量独占型；1信号量同享型
unsigned char OSEventState; //状况0,不可用;1,可用
unsigned char OSTaskPendTbl; //等候信号量的使命列表
} Sem[10];
//初始化信号量
void OSSemCreat(unsigned char Index,unsigned char Type)
{
Sem[Index].OSEventType=Type; //类型0,信号量独占型；1信号量同享型
Sem[Index].OSTaskPendTbl=0;
Sem[Index].OSEventState=0;
}
//使命等候信号量,挂起
unsigned char OSTaskSemPend(unsigned char Index,unsigned int Timeout)
{
//unsigned char i=0;
if(Sem[Index].OSEventState) //信号量有用
{
if(Sem[Index].OSEventType==0) //假如为独占型
Sem[Index].OSEventState = 0x00; //信号量被独占，不可用
}
else
{ //参加信号的使命等候表
Sem[Index].OSTaskPendTbl |= 0x01< OSRdyTbl &= ~(0x01< TCB[OSTaskRunningPrio].OSWaitTick=Timeout; //如延时为0，刚无限等候 OSSched(); //重新调度 if(TCB[OSTaskRunningPrio].OSWaitTick==0) return 0; } return 1; }
//发送一个信号量，能够从使命或中止发送
void OSSemPost(unsigned char Index)
{
if(Sem[Index].OSEventType) //当要求的信号量是同享型
{
Sem[Index].OSEventState=0x01; //使信号量有用
OSRdyTbl |=Sem [Index].OSTaskPendTbl; //使在等候该信号的一切使命安排妥当
Sem[Index].OSTaskPendTbl=0; //清空一切等候该信号的等候使命
}
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) //假如有使命需求 { Sem[Index].OSTaskPendTbl &= ~(0x01< OSRdyTbl |= 0x01< } else { Sem[Index].OSEventState =1; //使信号量有用 } } } //从使命发送一个信号量，并进行调度 void OSTaskSemPost(unsigned char Index) { OSSemPost(Index); OSSched(); } //铲除一个信号量,只对同享型的有用。 //关于独占型的信号量，在使命占用后，就交得不能够用了。 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) //当使命时钟届时,有必要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); //挂起使命1
OSTaskSemPost(0);
OSTimeDly(50);
OSTaskResume(1); //康复使命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(); //重复进行调度
}
}
int main(void)
{
TCN0Init();
OSRdyTbl=0;
OSSemCreat(0,1); //将信号量设为同享型
OSTaskCreate(Task0,&Stack[99],0);
OSTaskCreate(Task1,&Stack[199],1);
OSTaskCreate(Task2,&Stack[299],2);
OSTaskCreate(TaskScheduler,&Stack[399],OS_TASKS);
OSStartTask();
}
