#include "address_map_arm.h"
/* This program demonstrates use of parallel ports in the Computer System
 *
 * It performs the following:
 *  1. displays a rotating pattern on the green LED
 *  2. if a KEY is pressed, uses the SW switches as the pattern
*/
int main(void) {
    /* Declare volatile pointers to I/O registers (volatile means that IO load
     * and store instructions will be used to access these pointer locations,
     * instead of regular memory loads and stores)
    */
    volatile int * LED_ptr       = (int *)LED_BASE; // LED address
    volatile int * SW_switch_ptr = (int *)SW_BASE;  // SW slider switch address
    volatile int * KEY_ptr       = (int *)KEY_BASE; // pushbutton KEY address

    int LED_bits = 0x0F0F0F0F; // pattern for LED lights
    int SW_value, KEY_value;
    volatile int
        delay_count; // volatile so the C compiler doesn't remove the loop

    while (1) {
        SW_value = *(SW_switch_ptr); // read the SW slider (DIP) switch values

        KEY_value = *(KEY_ptr); // read the pushbutton KEY values
        if (KEY_value != 0)     // check if any KEY was pressed
        {
            /* set pattern using SW values */
            LED_bits = SW_value | (SW_value << 8) | (SW_value << 16) |
                       (SW_value << 24);
            while (*KEY_ptr)
                ; // wait for pushbutton KEY release
        }
        *(LED_ptr) = LED_bits; // light up the LEDs

        /* rotate the pattern shown on the LEDs */
        if (LED_bits & 0x80000000)
            LED_bits = (LED_bits << 1) | 1;
        else
            LED_bits = LED_bits << 1;

        for (delay_count = 350000; delay_count != 0; --delay_count)
            ; // delay loop
    }
}