#include <stdio.h>

/* sched.h */
#define MAX_USER_RT_PRIO        100
#define MAX_RT_PRIO             MAX_USER_RT_PRIO
#define MAX_PRIO                (MAX_RT_PRIO + 40)

/* sched.c */
#define NICE_TO_PRIO(nice)      (MAX_RT_PRIO + (nice) + 20)
#define PRIO_TO_NICE(prio)      ((prio) - MAX_RT_PRIO - 20)
#define TASK_NICE(p)            PRIO_TO_NICE((p)->static_prio)

#define USER_PRIO(p)            ((p)-MAX_RT_PRIO)
#define MAX_USER_PRIO           (USER_PRIO(MAX_PRIO))

#define PRIO_BONUS_RATIO        45      /* Between 45 and 49 */
#define INTERACTIVE_DELTA       2

#define SCALE(v1,v1_max,v2_max) \
        (v1) * (v2_max) / (v1_max)

#define DELTA(p) \
        (SCALE(TASK_NICE(p), 40, MAX_USER_PRIO*PRIO_BONUS_RATIO/100) + \
                INTERACTIVE_DELTA)

#define TASK_INTERACTIVE(p) \
        ((p)->prio <= (p)->static_prio - DELTA(p))

/*****************/

#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100 / 2)
#define MIN_BONUS (-MAX_BONUS)

typedef struct {
    int static_prio;
    int prio;
} mini_task_t;

static void write_values(int nice)
{
    int bonus;
    mini_task_t p;

    p.static_prio = NICE_TO_PRIO(nice);
    p.prio = p.static_prio + MIN_BONUS;

    printf("TASK_INTERACTIVE(%3d): [%d", nice, TASK_INTERACTIVE(&p));

    for (bonus = MIN_BONUS + 1; bonus <= MAX_BONUS; bonus++) {
        p.prio = p.static_prio + bonus;
        printf(",%d", TASK_INTERACTIVE(&p));
    }

    puts("]");
}

int main(void)
{
    printf("Interactivity bonus between %d and %d\n\n", MIN_BONUS, MAX_BONUS);

    write_values(-20);
    write_values(-10);
    write_values(0);
    write_values(10);
    write_values(19);

    puts("");
    printf("nice +19 interactive tasks : %d\n", NICE_TO_PRIO(19) - MAX_BONUS);
    printf("nice 0 CPU hogs : %d\n", NICE_TO_PRIO(0) - MIN_BONUS);

    puts("");
    printf("nice -20 CPU hogs : %d\n", NICE_TO_PRIO(-20) - MIN_BONUS);
    printf("nice 0 interactive tasks : %d\n", NICE_TO_PRIO(0) - MAX_BONUS);

    return 0;
}