cx-zivuos/sources/balanced_priority_scheduler.c

#include "kernel.h"
#include "scheduler.h"

#ifndef ZV_FULL_DISABLE_BALANCED_PRIORITY

zv_process_t * zv_kernel_balanced_priority(zv_kernel_t *self) {
    zv_process_t *selected = NULL;
    zv_process_t *last = self->processes + self->last;
    zv_priority_t selected_priority = 0;
    bool full_round = true;
    
    for (
        zv_process_t *current = self->processes;
        current != (self->processes + self->processes_count);
        ++current
    ) {
        if (current->priority > self->lowest_priority) {
            self->lowest_priority = current->priority;
        }

        if (current->priority == self->lowest_priority) {
            full_round = full_round && current->balance > 0; 
        }

        if (!zv_process_is_ready(current)) {
            continue;
        }
        
        zv_priority_t current_priority = _zv_process_calc_priority(current);

        if (current != last && current_priority > self->lowest_priority) {
            if (current->balance > 0) {
                --current->balance;
            }
        }

        if (selected == NULL) {
            selected = current;
            selected_priority = current_priority;
            continue;
        }

        if (current_priority <= selected_priority) {
            selected = current;
            selected_priority = current_priority;
            continue;
        }
    }

    if (full_round) {
        __zv_kernel_clean_balance(self);
        return zv_kernel_balanced_priority(self);
    }

    if (selected->balance < 255) {
        ++selected->balance;
    }

    return selected;
}

#else

zv_process_t * zv_kernel_balanced_priority(zv_kernel_t *self) {
    return NULL;
}

#endif