Traffic Light using switch

Code : 

#include<lpc214x.h>                  // Include LPC2138 library.

void delay(unsigned int a);          // Delay between 3 leds.

int main()                           // Main function starts.

{

PINSEL0 = 0X00000000;                // Port 0 is set to first config.

IODIR0 = 0X00000007;                 // Set P0.0 ,P0.1 & P0.2 in output config. 

IOSET0  = 0X00000007;                // Set  P0.0 ,P0.1 & P0.2 to high. 

while(1)                             // Infinite Loop

{

if((IOPIN1 & 0X00010000)==0)       // If Port 1.16 is low.

{

IOCLR0 = 0X00000001;                 // Red led turned on.

delay(4000);                         // Wait.

IOSET0  = 0X00000001;                // Red led turned off.

IOCLR0 =  0X00000002;                // Yellow led turned on.

delay(2000);                         // Wait.

IOSET0  = 0X00000002;                // Yellow led turned off.

IOCLR0 =  0X00000004;                // Green led turned on.

delay(1000);                        // Wait.

IOSET0  = 0X00000004;                // Green led turned off.

}

}

}

void delay(unsigned int a)           // Delay function

{

unsigned int b;                    // Assigning integer b. 

{

for(b=0;b<=1000*a;b++);          // For loop for delay

}

}