Example program for simulating 51 multitasking using C language on PC

#include

#include

//Number of task slots. In this example, task swapping is not considered, so how many tasks are actually running?

//Just define as many task slots as you want, no more or less

#define MAX_TASKS 5

//Task stack pointer

unsigned char *task_sp[MAX_TASKS];

// Maximum stack depth. The minimum is not less than 2, and the conservative value is 12.

//Estimation method: Take 2 as the base, add 2 bytes for each additional layer of function call.

//If an interrupt may occur during the process, the stack depth required by the interrupt must be added.

//Methods to reduce stack depth: 1. Nest subroutines as little as possible 2. Disable interrupts before calling subroutines.

#define MAX_TASK_DEP 12

unsigned char task_stack[MAX_TASKS][MAX_TASK_DEP] =

{

    0,1,2,3,4,5,6,7,8,9,'a',9,8,7,6,5,4,3,2,1,0,11,12,13,113,31,4

}; //Task stack.

//Task loading function. Load the specified function (parameter 1) into the specified (parameter 2) task slot.

//If there is already a task in the slot, the original task will be lost, but the system itself will not fail.

//Enter the low byte and high byte of each task's function address into

//task_stack[task number][0] and task_stack[task number][1]

void task_load(unsigned int fn, unsigned char tid)

{

task_sp[tid] = task_stack[tid] + 1;

task_stack[tid][0] = (unsigned int)fn & 0xff;

task_stack[tid][1] = (unsigned int)fn >> 8;

}

void func1()

{

static unsigned char i;

i = 0;

while(1)

{

if(i<250)

{

i++;

}

if(i>=250)

{

printf("task1n");

i = 0;

}

//task_switch();

}

}

void func2()

{

static unsigned int j;

j = 0;

while(1)

{

if(j<654)

{

j++;

}

if(j>=654)

{

printf("task2n");

j = 0;

}

//task_switch();

}

}

int main()

{

    printf("Hello world!n");

    printf("task_stack[0] = %pn",task_stack[0]);

    printf("task_stack+0 = %pn",task_stack+0);

    printf("task_stack+1 = %pn",task_stack+1);

    printf("task_stack+2 = %pn",task_stack+2);

    printf("task_stack+3 = %pn",task_stack+3);

    printf("task_stack+4 = %pn",task_stack+4);

    printf("task_stack[0] = %pn",task_stack[0]);

    printf("*(task_stack+0) = %pn",*(task_stack+0));

    printf("*(task_stack+1) = %pn",*(task_stack+1));

    printf("*(task_stack+2) = %pn",*(task_stack+2));

    printf("*(task_stack+3) = %pn",*(task_stack+3));

    printf("*(task_stack+4) = %pn",*(task_stack+4));

    printf("task_stack[0] = %pn",task_stack[0]);

    printf("*(task_stack+0)+0 = %pn",*(task_stack+0)+0);

    printf("*(task_stack+1)+1 = %pn",*(task_stack+1)+1);

    printf("*(task_stack+2)+2 = %pn",*(task_stack+2)+2);

    printf("*(task_stack+3)+3 = %pn",*(task_stack+3)+3);

    printf("*(task_stack+4)+4 = %pn",*(task_stack+4)+4);

    task_sp[0] = (task_stack[0]+1);

    task_sp[1] = (task_stack[0]+2);

    task_sp[2] = (task_stack[0]+3);

    task_sp[3] = (task_stack[0]+4);

    task_sp[4] = (task_stack[0]+5);

    //task_sp[0] = *(task_stack+0)+9;

    printf("task_stack = %pn",task_stack);

    printf("task_stack[0] + 5 = %pn",(task_stack[0] + 5));

    printf("task_sp = %pn",task_sp);

    printf("ntask_sp[0] = %dn",task_sp[0]);

    printf("task_sp[1] = %dn",task_sp[1]);

    printf("task_sp[2] = %dn",task_sp[2]);

    printf("task_sp[3] = %dn",task_sp[3]);

    printf("task_sp[4] = %dn",task_sp[4]);

    //task_load(func1, 0);//Load the func1 function into slot 0

//task_load(func2, 1);//Load the func2 function into slot 1

    return 0;

}

Hello world!

task_stack[0] = 00403000

task_stack+0 = 00403000

task_stack+1 = 0040300C

task_stack+2 = 00403018

task_stack+3 = 00403024

task_stack+4 = 00403030

task_stack[0] = 00403000

*(task_stack+0) = 00403000

*(task_stack+1) = 0040300C

*(task_stack+2) = 00403018

*(task_stack+3) = 00403024

*(task_stack+4) = 00403030

task_stack[0] = 00403000

*(task_stack+0)+0 = 00403000

*(task_stack+1)+1 = 0040300D

*(task_stack+2)+2 = 0040301A

*(task_stack+3)+3 = 00403027

*(task_stack+4)+4 = 00403034

task_stack = 00403000

task_stack[0] + 5 = 00403005

task_sp = 004050B0

task_sp[0] = 4206593

task_sp[1] = 4206594

task_sp[2] = 4206595

task_sp[3] = 4206596

task_sp[4] = 4206597

Terminated with return code 0

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