自己写的一个基于AVR单片机（Meag16）、编译器WINAVR20070122的调度程序，基于时间片轮转法，定时器0计时，轮流让8个任务运行，切换任务时保存全部寄存器R0-R31、SREG到当前任务的堆栽，然后恢复下一个任务的现场，用中断返回指令作任务切换。设置让编译器在中断程序不保存任何寄存器，由自己保存寄存器。
8个任务可以轮流运行，但是任务内部定义的局部在任务每次重新执行时都变为0。请教大家，谢谢了！程序代码如下：
（1）头文件：任务控制块TCB定义、保存任务环境的入栽宏、恢复任务现场的出栽宏。
typedef struct
{
unsigned char* task_stk_top; //保存任务的栽顶
unsigned char task_stack[100];//任务堆栽
}OS_TASK_TCB;
//保存所有寄存器的宏
#define pushall()
__asm__ __volatile__ ("push r1" "
");
__asm__ __volatile__ ("push r0" "
");
__asm__ __volatile__ ("in r0, 0x3f" "
");保存CPU状态寄存器
__asm__ __volatile__ ("push r0" "
");
__asm__ __volatile__ ("eor r1, r1" "
");WINAVR要求R1等于0
__asm__ __volatile__ ("push r2" "
");
__asm__ __volatile__ ("push r3" "
");
__asm__ __volatile__ ("push r4" "
");
__asm__ __volatile__ ("push r5" "
");
__asm__ __volatile__ ("push r6" "
");
__asm__ __volatile__ ("push r7" "
");
__asm__ __volatile__ ("push r8" "
");
__asm__ __volatile__ ("push r9" "
");
__asm__ __volatile__ ("push r10" "
");
__asm__ __volatile__ ("push r11" "
");
__asm__ __volatile__ ("push r12" "
");
__asm__ __volatile__ ("push r13" "
");
__asm__ __volatile__ ("push r14" "
");
__asm__ __volatile__ ("push r15" "
");
__asm__ __volatile__ ("push r16" "
");
__asm__ __volatile__ ("push r17" "
");
__asm__ __volatile__ ("push r18" "
");
__asm__ __volatile__ ("push r19" "
");
__asm__ __volatile__ ("push r20" "
");
__asm__ __volatile__ ("push r21" "
");
__asm__ __volatile__ ("push r22" "
");
__asm__ __volatile__ ("push r23" "
");
__asm__ __volatile__ ("push r24" "
");
__asm__ __volatile__ ("push r25" "
");
__asm__ __volatile__ ("push r26" "
");
__asm__ __volatile__ ("push r27" "
");
__asm__ __volatile__ ("push r28" "
");
__asm__ __volatile__ ("push r29" "
");
__asm__ __volatile__ ("push r30" "
");
__asm__ __volatile__ ("push r31" "
");
//恢复任务现场时弹出所有寄存器的宏
#define popall()
__asm__ __volatile__ ("pop r31" "
");
__asm__ __volatile__ ("pop r30" "
");
__asm__ __volatile__ ("pop r29" "
");
__asm__ __volatile__ ("pop r28" "
");
__asm__ __volatile__ ("pop r27" "
");
__asm__ __volatile__ ("pop r26" "
");
__asm__ __volatile__ ("pop r25" "
");
__asm__ __volatile__ ("pop r24" "
");
__asm__ __volatile__ ("pop r23" "
");
__asm__ __volatile__ ("pop r22" "
");
__asm__ __volatile__ ("pop r21" "
");
__asm__ __volatile__ ("pop r20" "
");
__asm__ __volatile__ ("pop r19" "
");
__asm__ __volatile__ ("pop r18" "
");
__asm__ __volatile__ ("pop r17" "
");
__asm__ __volatile__ ("pop r16" "
");
__asm__ __volatile__ ("pop r15" "
");
__asm__ __volatile__ ("pop r14" "
");
__asm__ __volatile__ ("pop r13" "
");
__asm__ __volatile__ ("pop r12" "
");
__asm__ __volatile__ ("pop r11" "
");
__asm__ __volatile__ ("pop r10" "
");
__asm__ __volatile__ ("pop r9" "
");
__asm__ __volatile__ ("pop r8" "
");
__asm__ __volatile__ ("pop r7" "
");
__asm__ __volatile__ ("pop r6" "
");
__asm__ __volatile__ ("pop r5" "
");
__asm__ __volatile__ ("pop r4" "
");
__asm__ __volatile__ ("pop r3" "
");
__asm__ __volatile__ ("pop r2" "
");
__asm__ __volatile__ ("pop r0" "
");
__asm__ __volatile__ ("out 0x3f, r0" "
");恢复CPU状态寄存器
__asm__ __volatile__ ("pop r0" "
");
__asm__ __volatile__ ("pop r1" "
");
__asm__ __volatile__ ("RETI" "
");
//******************************************************************
（2）主函数main()代码，包括8个任务，调度程序，定义8个任务，每个任务对应一个LED灯的闪烁：
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include "RTOS.h"
#define LED_PORT PORTA //LED端口定义
#define LED_DDR DDRA
#define LED_PIN PINA
//第1个任务定义
void task1( void )
{
unsigned char temp ;//任务1的局部变量
TCCR0 = 0X05;//定时器0初始化
TIMSK = 0X01;
TCNT0 = 0x00;
sei(); //打开全局中断
while(1)
{
//任务1每次重新执行temp都会变为0，就是这里请教大家为什么？
temp++;
LED_PORT ^=0X01;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第2个任务定义
void task2(void)
{
while(1)
{
LED_PORT ^=0X02;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第3个任务定义
void task3(void)
{
while(1)
{
LED_PORT ^=0X04;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第4个任务定义
void task4(void)
{
while(1)
{
LED_PORT ^=0X08;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第5个任务定义
void task5(void)
{
while(1)
{
LED_PORT ^=0X10;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第6个任务定义
void task6(void)
{
while(1)
{
LED_PORT ^=0X20;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第7个任务定义
void task7(void)
{
while(1)
{
LED_PORT ^=0X40;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//第8个任务定义
void task8(void)
{
while(1)
{
LED_PORT ^=0X80;
for( unsigned char i=0; i<250; i++)
_delay_ms(10);
}
}
//*******************************************************************
volatile unsigned char next_task = 0;//用来计算下一个运行的任务
//计数变量，在定时器0中断函数里加1，用来控制任务切换频率
volatile unsigned char count = 0;
volatile OS_TASK_TCB task_tcb[ 8 ];//定义8个任务的任务控制块TCB数组
//任务堆栽初始化函数，参数为：任务入口地址、任务序号（1-8）
unsigned char* stackinit( void (*task)( void ), unsigned char task_id )
{
unsigned char* stk;
unsigned int temp;
temp = (unsigned int)task;//任务入口地址
stk = &( task_tcb[task_id].task_stack[99] );//取得任务栽顶指针
*stk-- = (unsigned char)(temp&0xff);//将任务入口地址入栽
*stk-- = (unsigned char)(temp>>8);
//以下是CPU所有寄存器初始化，为0值，
*stk-- = (unsigned char)0x00; /* R0 = 0x00 */
*stk-- = (unsigned char)0x00; /* R1 = 0x00 */
*stk-- = (unsigned char)0x80; /* R2 = 0x00 */
*stk-- = (unsigned char)0x00; /* R3 = 0x00 */
*stk-- = (unsigned char)0x00; /* R4 = 0x00 */
*stk-- = (unsigned char)0x00; /* R5 = 0x00 */
*stk-- = (unsigned char)0x00; /* R6 = 0x00 */
*stk-- = (unsigned char)0x00; /* R7 = 0x00 */
*stk-- = (unsigned char)0x00; /* R8 = 0x00 */
*stk-- = (unsigned char)0x00; /* R9 = 0x00 */
*stk-- = (unsigned char)0x00; /* R10 = */
*stk-- = (unsigned char)0x00; /* R11 = */
*stk-- = (unsigned char)0x00; /* R12 = */
*stk-- = (unsigned char)0x00; /* R13 = */
*stk-- = (unsigned char)0x00; /* R14 = */
*stk-- = (unsigned char)0x00; /* R15 = */
*stk-- = (unsigned char)0x00; /* R16 = */
*stk-- = (unsigned char)0x00; /* R17 = */
*stk-- = (unsigned char)0x00; /* R18 = */
*stk-- = (unsigned char)0x00; /* R19 = */
*stk-- = (unsigned char)0x00; /* R20 = */
*stk-- = (unsigned char)0x00; /* R21 = */
*stk-- = (unsigned char)0x00; /* R22 = */
*stk-- = (unsigned char)0x00; /* R23 = */
*stk-- = (unsigned char)0x00; /* R24 = 0x00 */
*stk-- = (unsigned char)0x00; /* R25 = 0x00 */
*stk-- = (unsigned char)0x00; /* R26 = */
*stk-- = (unsigned char)0x00; /* R27 = */
*stk-- = (unsigned char)0x00; /* R28 = */
*stk-- = (unsigned char)0x00; /* R29 = */
*stk-- = (unsigned char)0x00; /* R30 = */
*stk-- = (unsigned char)0x00; /* R31 = */
*stk-- = (unsigned char)0x00; /* SREG = */
return ( (unsigned char*)stk );//返回当前堆栈指针
}
//任务创建函数：
void taskcreat( void (*task)( void ), unsigned char task_id )
{
unsigned char *temp;
temp = stackinit( task, task_id );//堆栽初始化，并返回栽顶指针
//初始化之后将堆栽栽顶指针保存在任务的TCB里，这个变量一直指向栽顶
task_tcb[task_id].task_stk_top = temp;
}
void OS_Start( void )
{
SP = task_tcb[0].task_stk_top + 33;//堆栽指针指向第一个任务
//用中断返回指令将入口地址弹出到PC指针，运行第一个任务
asm("RETI");
}
//定时器0的中断函数：加上下面这句，WINAVR将不保存任何寄存器
void SIG_OVERFLOW0( void ) __attribute__ ( ( signal, naked ) );
SIGNAL( SIG_OVERFLOW0 )
{
pushall( );//自己人工保存所有寄存器
count++; //每次中断加1
if(count>100)//100时任务切换，count值可以调整任务切换频率
{
count = 0;//重新清0
next_task++;指向下一个任务
//堆栽指针指向下一个任务栽顶
SP = task_tcb[ next_task % 8 ].task_stk_top;
}
popall( );//人工恢复所有寄存器
}
//main()函数
int main( void )
{
//LED灯控制端口设置
LED_PORT=0Xff;
LED_DDR =0Xff;
//创建并初始化8个任务
taskcreat( task1, 0 );
taskcreat( task2, 1 );
taskcreat( task3, 2 );
taskcreat( task4, 3 );
taskcreat( task5, 4 );
taskcreat( task6, 5 );
taskcreat( task7, 6 );
taskcreat( task8, 7 );
OS_Start( );//开始运行任务
while( 1 );
}//****************************************************************
我的问题就是任务1内部定义的局部变量temp为什么每次在任务1重新执行都为从0开始。这个时自己学习RTOS写的，请大家多指教！我想不断的进步，谢谢了！
祝大家中秋快乐，工作顺心，呵呵！ |
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