只有延时服务的协作式的内核

一、rtos.c

/*
* 只有延时服务的协作式的内核
*
* 三个正在运行的主任务，都通过延时服务，主动放弃对CPU的控制权。 在时间中断中，
* 对各个任务的的延时进行计时，如果某个任务的延时结束，将任务重新在就绪表中置
* 位。 最低级的系统任务TaskScheduler()，在三个主任务在放弃对CPU的控制权后开始
* 不断地进行调度。如果某个任务在就绪表中置位，通过调度，进入最高级别的任务中
* 继续运行。
*
* 单片机：AT90CAN128
* 编译软件：WinAVR-20090313，AVR Studio 4.16
*/
#include "rtos.h"
unsigned char Stack[200];
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           //任务控制块
{
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 tempR17 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--=(unsigned int)Task>>8;
*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<<TaskID;      //任务就绪表已经准备好
}
//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      \n\t");  //从中断中返回，并开中断
}
//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__         \n\t");  //R1
__asm__ __volatile__("PUSH __tmp_reg__          \n\t");  //R0
__asm__ __volatile__("IN   __tmp_reg__,__SREG__ \n\t");  //保存状态寄存器SREG
__asm__ __volatile__("PUSH __tmp_reg__          \n\t");
__asm__ __volatile__("CLR  __zero_reg__         \n\t");  //R0重新清零
__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用于建立在堆栈上的指针
__asm__ __volatile__("PUSH R29                  \n\t");  //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));
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                  \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 出栈并恢复
__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
//中断时出栈完成
}
void OSTimeDly(unsigned int ticks)
{
if(ticks)                             //当延时有效
{
OSRdyTbl &= ~(0x01<<OSTaskRunningPrio);
TCB[OSTaskRunningPrio].OSWaitTick=ticks;
OSSched();                          //从新调度
}
}
void TCN0Init(void)    // 计时器0
{
TCCR0A = 0x00;  //关定时器  0x05是定时器普通模式、1024分频
TCNT0 = 0x16;      //初始值  (256-22)*0.08533333=19.9679999999ms
TIMSK0 |= (1<<TOIE0);  //中断允许
//    TCCR0A |= (1<<WGM01) | (1<<CS02) | (1<<CS00);   //启动，CTC模式，1024分频 ;加1<<WGM01不好用
TCCR0A |= (1<<CS02) | (1<<CS00);   //启动，普通模式，1024分频
//12000000/1024=11718.75, 1/11718.75=85.33333us
}
SIGNAL(SIG_OVERFLOW0)
{
unsigned char i;
for(i=0;i<OS_TASKS;i++)       //任务时钟
{
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<<i);     //使任务在就绪表中置位
}
}
}
TCNT0=0x16;
}
void Task0()
{
while(1)
{
GREEN_OFF;
YELLOW_ON;
OSTimeDly(20);
}
}
void Task1()
{
while(1)
{
GREEN_ON;
YELLOW_OFF;
OSTimeDly(40);
}
}
void Task2()
{
while(1)
{
GREEN_OFF;
YELLOW_OFF;
OSTimeDly(80);
}
}
void TaskScheduler()
{
while(1)
{
OSSched();//反复进行调度
}
}
int main(void)
{
TCN0Init();
LedsInitial();
OSRdyTbl=0;
OSTaskRunningPrio=0;
OSTaskCreate(Task0,&Stack[49],0);
OSTaskCreate(Task1,&Stack[99],1);
OSTaskCreate(Task2,&Stack[149],2);
OSTaskCreate(TaskScheduler,&Stack[199],OS_TASKS);
OSStartTask();
}

二、rtos.h

#ifndef __RTOS_H__
#define __RTOS_H__
#include "includes.h"
#include "config.h"
#endif

三、config.c

#include "config.h"
void LedsInitial(void)
{
DDRG |= (1<<DDG3)|(1<<DDG0);     //output
//  GREEN_ON;
//  YELLOW_ON;
GREEN_OFF;
YELLOW_OFF;
}

四、config.h

#ifndef __CONFIG_H__
#define __CONFIG_H__
#include "includes.h"
#define GREEN    _BV(PG3)
#define YELLOW   _BV(PG0)
/*
* LED共阳接+5V
* 负极接单片机IO口
*/
#define GREEN_ON   PORTG &= ~(GREEN)    //GREEN是低电平
#define GREEN_OFF  PORTG |= (GREEN)     //GREEN是高电平
#define YELLOW_ON  PORTG &= ~(YELLOW)
#define YELLOW_OFF PORTG |= (YELLOW)
extern void LedsInitial(void);
#endif

五、includes.h

#ifndef __INCLUDES_H__
#define __INCLUDES_H__
#include <alloca.h>// Allocate space in the stack
#include <assert.h>// Diagnostics
#include <ctype.h>// Character Operations
#include <errno.h>// System Errors
#include <inttypes.h>// Integer Type conversions
#include <math.h>// Mathematics
#include <setjmp.h>// Non-local goto
#include <stdint.h>// Standard Integer Types
#include <stdio.h>// Standard IO facilities
#include <stdlib.h>// General utilities
#include <string.h>// Strings
//
#include <avr/boot.h>// Bootloader Support Utilities
#include <avr/eeprom.h>// EEPROM handling
#include <avr/fuse.h>// Fuse Support
#include <avr/interrupt.h>// Interrupts
#include <avr/io.h>// AVR device-specific IO definitions
#include <avr/lock.h>// Lockbit Support
#include <avr/pgmspace.h>// Program Space Utilities
#include <avr/power.h>// Power Reduction Management
#include <avr/sleep.h>// Power Management and Sleep Modes
#include <avr/wdt.h>// Watchdog timer handling
#include <util/atomic.h>// Atomically and Non-Atomically Executed Code Blocks
#include <util/crc16.h>// CRC Computations
#include <util/delay.h>// Convenience functions for busy-wait delay loops
#include <util/delay_basic.h>// Basic busy-wait delay loops
#include <util/parity.h>// Parity bit generation  #include <util/setbaud.h>// Helper macros for baud rate calculations
#include <util/twi.h>// TWI bit mask definitions
#include <compat/deprecated.h>// Deprecated items
#include <compat/ina90.h>// Compatibility with IAR EWB 3.x
#endif