RN-Praxis2/lookup.c

#include "lookup.h"

static int free_space = TABLE_SIZE;
static lookup_head *table;

void init_lookup_table()
{
    table = malloc(sizeof(lookup_head));
    if (table == NULL) return;
    table->head = NULL;
}

void push_lookup(lookup_request *request)
{
    if (free_space == 0)
    {
        lookup_table *infront = table->head;
        while (infront->next != NULL && infront->next->next != NULL)
        {
            infront = infront->next;
        }

        free(infront->next->request);
        free(infront->next);
        infront->next = NULL;
        // if malloc fails this does not leak space
        free_space++;
    }

    lookup_table *new = (lookup_table*)malloc(sizeof(lookup_table));
    if (new == NULL) return;
    new->request = request;
    new->next = table->head;
    table->head = new;
    free_space--;
}

lookup_request *find_lookup(const uint16_t hash_id)
{
    const lookup_table *current = table->head;

    while (current != NULL){
        if((current->request->node_id < current->request->hash_id && (hash_id > current->request->hash_id && hash_id < 65535)) || hash_id <= current->request->node_id || (hash_id > current->request->hash_id && hash_id <= current->request->node_id))
            break;
        current = current->next;
    }
    return current == NULL ? NULL : current->request;
}

void free_lookup_table()
{
    if (table == NULL) return;
    lookup_table *current = table->head;

    while (current != NULL)
    {
        lookup_table *temp = current;
        current = current->next;
        free(temp->request);
        free(temp);
    }
    free(table);
    table = NULL;
    free_space = TABLE_SIZE;
}