Program for single-chip microcomputer to control LED lighting with a single button

The program of 51 single-chip microcomputer single-button control LED light emission is to use a button connected to P3_0 pin to control the two states of LED connected to P2_0, namely, on and off. Press the button once and the light will turn on, press the button again and the light will turn off. Press it again and the light will turn on again, press it again and the light will turn off again. This program comes from the single-chip microcomputer website: http://www.51hei.com, and it has been successfully run after testing.
#include "AT89X51.H"
void main(void) // Main program
{
bit mark; //Define bit variable
unsigned int n; //Define loop variable
while(1) //Infinite loop
{
if (P3_0==0) //If the button is pressed
{
for(n=0;n<1000;n++); //Delay for a while, waiting for the button to be fully pressed
mark=~mark; //Flip mark
while(!P3_0) //Wait for the button to pop up
for(n=0;n<1000;n++); //Wait for the button to pop up
}
P2_0=mark; //Turn on or off the LED light
}}
while(1) //Infinite loop
{
if(ldelay==1 ) //If the time overflow mark is 1, process the following statement
{
ldelay=0; //Clear the time overflow mark
P2=ledp[ledi]; //Read a table value and send it to P2 port
ledi++; //Point to the next table value
if(ledi==4)
{
ledi=0; //When it reaches the last light, switch to the first
sp--; //Speed ​​level minus 1
if (sp==3) //If the speed level is reduced to 3
sp=23; //Restore the slowest level 23
}}}}
timer0() interrupt 1 //Timer 0 interrupt service program
{
static unsigned int kk; //Define static local variable
kk++; //Each interrupt service, kk increases by 1
if(kk==(100*sp)) //The minimum number of times is 100*sp=300, and the time is 300 times*0.25ms
//The maximum number of times is 2300 times, and the time is 2300 times*0.25ms
//If kk=(100*sp), execute the following statement
{
kk=0;
ldelay=1; //When the kk value is equal to the 100*sp value, set the ldelay flag to 1, and then process the light and display speed
} }