ddwrt c++ gpio led load average monitor

/*
 *  Blink load average indicator for DLink dir-320
 *  moddified by billic.
 *  original taked from http://svn.dd-wrt.com:8000/browser/src/router/libutils/gpio.c
 *  License: GPL
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>


#define LA_EXTREME 200
#define LA_VHIGH 135
#define LA_HIGH 95
#define LA_MIDDLE 75
#define LA_NORMAL 35

#define RED_LED 3
#define BLU_LED 4
#define BUTTON 6

#define BLINK_ON 20000L
#define BLINK_OFF 80000L

/*
    blinks:
    1) one short            BLINK_ON + BLINK_OFF + 0.9
    2) two short            (BLINK_ON + BLINK_OFF)*2 + 0.8
    3) four short           (BLINK_ON + BLINK_OFF)*4 + 0.6
    4) eight short          (BLINK_ON + BLINK_OFF)*8 + 0.2
    -1) two long w short break  (0.4 + 0.1)*2

    blink_interval ~1sec

*/


void set_gpio (int pin, int value)
{

        int gpioouten = open("/dev/gpio/outen", O_RDWR);
        int gpioout = open("/dev/gpio/out", O_RDWR);
        unsigned int gpio;
        read(gpioouten, &gpio, sizeof(gpio));
        gpio |= 1 << pin;
        write(gpioouten, &gpio, sizeof(gpio));
        read(gpioout, &gpio, sizeof(gpio));
        if (value) {
                gpio |= (1 << pin);
        } else {
                gpio &= ~(1 << pin);
        }
        write(gpioout, &gpio, sizeof(gpio));
        close(gpioout);
        close(gpioouten);
}

int get_gpio(int pin)
{
        unsigned int gpio;
        int gpioouten = open("/dev/gpio/outen", O_RDWR);
        int gpioin = open("/dev/gpio/in", O_RDWR);
        read(gpioouten, &gpio, sizeof(gpio));
        gpio &= ~(1 << pin);
        write(gpioouten, &gpio, sizeof(gpio));
        read(gpioin, &gpio, sizeof(gpio));
        gpio = (gpio & (1 << pin)) ? 1 : 0;
        close(gpioin);
        close(gpioouten);
        return gpio;
}

int get_load_avg()
{
        int proc_la = open ("/proc/loadavg", O_RDONLY);
        char la[4];
        read (proc_la, &la, 4);
        la[1]=la[2];la[2]=la[3];la[3]=0;
    close (proc_la);
        return atoi(la);
}


inline void one_blink(int led)
{
    set_gpio(led, 0);
    usleep (BLINK_ON);
    set_gpio(led, 1);
    usleep (BLINK_OFF);
}

int blink(int led, int mode)
{
    switch (mode)
    {
        case 1:
            one_blink(led);
            usleep (900000);
            break;
        case 2:
            one_blink(led);
            one_blink(led);
            usleep (800000);
            break;
        case 3:
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            usleep (600000);
            break;
        case 4:
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            one_blink(led);
            usleep (200000);
            break;
        case -1:
            set_gpio(led, 0);
            usleep (400000);
            set_gpio(led, 1);
            usleep (100000);
            set_gpio(led, 0);
            usleep (400000);
            set_gpio(led, 1);
            usleep (100000);
            break;
        default:
            break;
    }
    return 0;
}

int show_la(int la)
{
    if (la >= LA_EXTREME)
      blink(RED_LED, -1);
    else if (la >= LA_VHIGH)
      blink(RED_LED, 3);
    else if (la >= LA_HIGH)
      blink(BLU_LED, 4);
    else if (la >= LA_MIDDLE)
      blink(BLU_LED, 3);
    else if (la >= LA_NORMAL)
      blink(BLU_LED, 2);
    else
      blink (BLU_LED, 1);

    return 0;
}

int show_switch ()
{
    one_blink (BLU_LED);
    one_blink (BLU_LED);
    one_blink (RED_LED);
    one_blink (RED_LED);
    return 0;
}

int show_start ()
{
    set_gpio(BLU_LED, 0);
    usleep(250000);
    set_gpio(RED_LED, 0);
    usleep(250000);
    set_gpio(BLU_LED, 1);
    usleep(250000);
    set_gpio(RED_LED, 1);
    usleep(250000);
    return 0;
}

int main(int argc, char **argv)
{
        unsigned int gpio;
        unsigned int old_gpio = -1;
        unsigned int pin;


    int i=1;
    show_start ();

    while (true)
    {
        if (!get_gpio(BUTTON))
        {
            i ? i = 0 : i = 1;
            show_switch();
        }

        if (i)
          show_la(get_load_avg());
        else
          usleep (1000000);
    }
        return 0;
}