建立一個(gè)AVR的RTOS（5）—完善的協(xié)作式的內(nèi)核

現(xiàn)在為上面的協(xié)作式內(nèi)核添加一些OS中所必須的服務(wù)：

1、掛起和重新運(yùn)行任務(wù)

2、信號(hào)量(在必要時(shí)候，可以擴(kuò)展成郵箱和信息隊(duì)列)

3、延時(shí)

#include <avr/io.h>

#include

#include

unsigned char Stack[400];

register unsigned char OSRdyTbl asm("r2"); //任務(wù)運(yùn)行就緒表

register unsigned char OSTaskRunningPrio asm("r3"); //正在運(yùn)行的任務(wù)

#define OS_TASKS 3 //設(shè)定運(yùn)行任務(wù)的數(shù)量

struct TaskCtrBlock

{

unsigned int OSTaskStackTop; //保存任務(wù)的堆棧頂

unsigned int OSWaitTick; //任務(wù)延時(shí)時(shí)鐘

} TCB[OS_TASKS+1];

//防止被編譯器占用

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");

//建立任務(wù)

void OSTaskCreate(void (*Task)(void),unsigned char *Stack,unsigned char TaskID)

{

unsigned char i;

*Stack--=(unsigned int)Task>>8; //將任務(wù)的地址高位壓入堆棧，

*Stack--=(unsigned int)Task; //將任務(wù)的地址低位壓入堆棧，

*Stack--=0x00; //R1 __zero_reg__

*Stack--=0x00; //R0 __tmp_reg__

*Stack--=0x80;

//SREG在任務(wù)中，開啟全局中斷

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; //將人工堆棧的棧頂，保存到堆棧的數(shù)組中

OSRdyTbl|=0x01<

}

//開始任務(wù)調(diào)度,從最低優(yōu)先級(jí)的任務(wù)的開始

void OSStartTask()

{

OSTaskRunningPrio=OS_TASKS;

SP=TCB[OS_TASKS].OSTaskStackTop+17;

__asm__ __volatile__( "reti" "nt" );

}

//進(jìn)行任務(wù)調(diào)度

void OSSched(void)

{

//根據(jù)中斷時(shí)保存寄存器的次序入棧，模擬一次中斷后，入棧的情況

__asm__ __volatile__("PUSH __zero_reg__ nt"); //R1

__asm__ __volatile__("PUSH __tmp_reg__ nt"); //R0

__asm__ __volatile__("IN __tmp_reg__,__SREG__ nt"); //保存狀態(tài)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與R29用于建立在堆棧上的指針

__asm__ __volatile__("PUSH R29 nt"); //入棧完成

TCB[OSTaskRunningPrio].OSTaskStackTop=SP; //將正在運(yùn)行的任務(wù)的堆棧底保存

unsigned char OSNextTaskID; //在現(xiàn)有堆棧上開設(shè)新的空間

for (OSNextTaskID = 0; //進(jìn)行任務(wù)調(diào)度

OSNextTaskID < OS_TASKS && !(OSRdyTbl & (0x01<

OSNextTaskID++);

OSTaskRunningPrio = OSNextTaskID ;

cli(); //保護(hù)堆棧轉(zhuǎn)換

SP=TCB[OSTaskRunningPrio].OSTaskStackTop;

sei();

//根據(jù)中斷時(shí)的出棧次序

__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出棧并恢復(fù)

__asm__ __volatile__("OUT __SREG__,__tmp_reg__ nt"); //

__asm__ __volatile__("POP __tmp_reg__ nt"); //R0出棧

__asm__ __volatile__("POP __zero_reg__ nt"); //R1出棧

//中斷時(shí)出棧完成

}

////////////////////////////////////////////任務(wù)處理

//掛起任務(wù)

void OSTaskSuspend(unsigned char prio)

{

TCB[prio].OSWaitTick=0;

OSRdyTbl &= ~(0x01<

if(OSTaskRunningPrio==prio) //當(dāng)要掛起的任務(wù)為當(dāng)前任務(wù)

OSSched(); //從新調(diào)度

}

//恢復(fù)任務(wù)可以讓被OSTaskSuspend或OSTimeDly暫停的任務(wù)恢復(fù)

void OSTaskResume(unsigned char prio)

{

OSRdyTbl |= 0x01<

TCB[prio].OSWaitTick=0; //將時(shí)間計(jì)時(shí)設(shè)為0,到時(shí)

if(OSTaskRunningPrio>prio) //當(dāng)要當(dāng)前任務(wù)的優(yōu)先級(jí)低于重置位的任務(wù)的優(yōu)先級(jí)

OSSched(); //從新調(diào)度//從新調(diào)度

}

//任務(wù)延時(shí)

void OSTimeDly(unsigned int ticks)

{

if(ticks) //當(dāng)延時(shí)有效

{

OSRdyTbl &= ~(0x01<

TCB[OSTaskRunningPrio].OSWaitTick=ticks;

OSSched(); //從新調(diào)度

}

}

//信號(hào)量

struct SemBlk

{

unsigned char OSEventType; //型號(hào)0,信號(hào)量獨(dú)占型；1信號(hào)量共享型

unsigned char OSEventState; //狀態(tài)0,不可用;1,可用

unsigned char OSTaskPendTbl; //等待信號(hào)量的任務(wù)列表

} Sem[10];

//初始化信號(hào)量

void OSSemCreat(unsigned char Index,unsigned char Type)

{

Sem[Index].OSEventType=Type; //型號(hào)0,信號(hào)量獨(dú)占型；1信號(hào)量共享型

Sem[Index].OSTaskPendTbl=0;

Sem[Index].OSEventState=0;

}

//任務(wù)等待信號(hào)量,掛起

unsigned char OSTaskSemPend(unsigned char Index,unsigned int Timeout)

{

//unsigned char i=0;

if(Sem[Index].OSEventState) //信號(hào)量有效

{

if(Sem[Index].OSEventType==0) //如果為獨(dú)占型

Sem[Index].OSEventState = 0x00; //信號(hào)量被獨(dú)占，不可用

}

else

{ //加入信號(hào)的任務(wù)等待表

Sem[Index].OSTaskPendTbl |= 0x01<

OSRdyTbl &= ~(0x01<

TCB[OSTaskRunningPrio].OSWaitTick=Timeout; //如延時(shí)為0，剛無(wú)限等待

OSSched(); //從新調(diào)度

if(TCB[OSTaskRunningPrio].OSWaitTick==0) return 0;

}

return 1;

}

//發(fā)送一個(gè)信號(hào)量，可以從任務(wù)或中斷發(fā)送

void OSSemPost(unsigned char Index)

{

if(Sem[Index].OSEventType) //當(dāng)要求的信號(hào)量是共享型

{

Sem[Index].OSEventState=0x01; //使信號(hào)量有效

OSRdyTbl |=Sem [Index].OSTaskPendTbl; //使在等待該信號(hào)的所有任務(wù)就緒

Sem[Index].OSTaskPendTbl=0; //清空所有等待該信號(hào)的等待任務(wù)

}

else //當(dāng)要求的信號(hào)量為獨(dú)占型

{

unsigned char i;

for (i = 0; i < OS_TASKS && !(Sem[Index].OSTaskPendTbl & (0x01<

if(i < OS_TASKS) //如果有任務(wù)需要

{

Sem[Index].OSTaskPendTbl &= ~(0x01<

OSRdyTbl |= 0x01<

}

else

{

Sem[Index].OSEventState =1; //使信號(hào)量有效

}

}

}

//從任務(wù)發(fā)送一個(gè)信號(hào)量，并進(jìn)行調(diào)度

void OSTaskSemPost(unsigned char Index)

{

OSSemPost(Index);

OSSched();

}

//清除一個(gè)信號(hào)量,只對(duì)共享型的有用。

//對(duì)于獨(dú)占型的信號(hào)量，在任務(wù)占用后，就交得不可以用了。

void OSSemClean(unsigned char Index)

{

Sem[Index].OSEventState =0; //要求的信號(hào)量無(wú)效

}

void TCN0Init(void) //計(jì)時(shí)器0

{

TCCR0 = 0;

TCCR0 |= (1<

TIMSK |= (1<

TCNT0 = 100; //置計(jì)數(shù)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) //當(dāng)任務(wù)時(shí)鐘到時(shí),必須是由定時(shí)器減時(shí)的才行

{

OSRdyTbl |= (0x01<

}

}

}

TCNT0=100;

}

void Task0()

{

unsigned int j=0;

while(1)

{

PORTB=j++;

OSTaskSuspend(1); //掛起任務(wù)1

OSTaskSemPost(0);

OSTimeDly(50);

OSTaskResume(1); //恢復(fù)任務(wù)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(); //反復(fù)進(jìn)行調(diào)度

}

}

int main(void)

{

TCN0Init();

OSRdyTbl=0;

OSSemCreat(0,1); //將信號(hào)量設(shè)為共享型

OSTaskCreate(Task0,&Stack[99],0);

OSTaskCreate(Task1,&Stack[199],1);

OSTaskCreate(Task2,&Stack[299],2);

OSTaskCreate(TaskScheduler,&Stack[399],OS_TASKS);

OSStartTask();

}