core/list.c

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#include <stdlib.h>
#include <errno.h>
#include "list.h"

static LISTITEM *create_item(void *data,    /* a pointer to the data */
                             LISTITEM *prev,    /* the item preceding the new item */
                             LISTITEM *next)    /* the item following the new item */
{
    LISTITEM *item = malloc(sizeof(LISTITEM));
    if (item!=NULL)
    {
        item->data = data;
        item->next = next;
        item->prev = prev;
    }
    else
        errno = ENOMEM;
    return item;
}

static void destroy_item(LISTITEM *item) 
{
    if (item->prev!=NULL) 
        item->prev->next = item->next;
    if (item->next!=NULL) 
        item->next->prev = item->prev;
    free(item);
}

LIST *list_create(void)
{
    LIST *list = malloc(sizeof(LIST));
    if (list!=NULL)
    {
        list->first = NULL;
        list->last = NULL;
        list->size = 0;
    }
    else
        errno = ENOMEM;
    return list;
}

void list_destroy(LIST *list) 
{
    LISTITEM *item;
    for (item=list->first; item!=NULL; item=item->next)
    {
        destroy_item(item);
        list->size--;
    }
    /* list size should be zero here */
}

LISTITEM *list_append(LIST *list, 
                      void *data) 
{
    LISTITEM *item = create_item(data,list->last,NULL);
    if (item!=NULL) {
        if (list->first==NULL)
            list->first = item;
        if (list->last!=NULL)
            list->last->next = item;
        list->last = item;
        list->size++;
    }
    return item;
}

void list_shuffle(LIST *list)
{
    LISTITEM **index;
    unsigned int i=0;
    LISTITEM *item;

    if (list == NULL)
        return;
    if (list->size < 2)
        return;

    index = (LISTITEM**)malloc(sizeof(LISTITEM*)*list->size);
    for (item=list->first; item!=NULL; item=item->next)
        index[i++] = item;
    for (i=0; i<list->size; i++)
    {
        LISTITEM *from = index[i], *to;
        unsigned int j = rand() % list->size;
        void *temp = from->data;
        to = index[j];
        from->data = to->data;
        to->data = temp;
    }
    free(index);
}

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GridLAB-D^TM Version 1.0

An open-source project initiated by the US Department of Energy