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n2n_list.c
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n2n_list.c
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/*
* n2n_list.c
*
* Created on: Aug 31, 2012
* Author: Costin Lupu
*/
#include "n2n.h"
#include "n2n_list.h"
#include "n2n_log.h"
#include <assert.h>
/**
* Return the number of elements in the list.
*/
size_t list_size(const n2n_list_head_t *head)
{
size_t count = 0;
const n2n_list_node_t *node = NULL;
LIST_FOR_EACH_NODE(head, node)
{
++count;
}
return count;
}
/**
* Purge all items from the list and return the number
* of items that were removed.
*/
size_t list_clear(n2n_list_head_t *head)
{
size_t count = 0;
n2n_list_node_t *scan = NULL;
n2n_list_node_t *next = NULL;
LIST_FOR_EACH_NODE_SAFE(head, scan, next)
{
free(scan); /* free list entry */
++count;
}
list_head_init(head);
return count;
}
void list_reverse(n2n_list_head_t *head)
{
n2n_list_head_t aux = *head;
n2n_list_node_t *scan = NULL;
n2n_list_node_t *next = NULL;
list_head_init(head);
LIST_FOR_EACH_NODE_SAFE(&aux, scan, next)
{
list_add(head, scan);
}
}
/**
* Merge sort
*/
static void merge(n2n_list_node_t *left, size_t left_size,
n2n_list_node_t *right, size_t right_size,
n2n_list_head_t *merged,
cmp_func_t cmp);
static void merge_sort(n2n_list_head_t *head, size_t size, cmp_func_t func)//TODO may just sort first 'size' entries
{
size_t i, middle;
LIST_HEAD(left);
LIST_HEAD(right);
LIST_HEAD(merged);
n2n_list_node_t *left_last = NULL;
if (size < 2)
return;
/* else list size is > 1, so split the list into two sublists */
middle = size / 2;
LIST_FIRST_NODE(&left) = LIST_FIRST_NODE(head);
for (i = 0, left_last = LIST_FIRST_NODE(head); i < middle - 1; i++)
{
left_last = left_last->next;
}
LIST_FIRST_NODE(&right) = left_last->next;
left_last->next = NULL;
merge_sort(&left, middle, func);
merge_sort(&right, size - middle, func);
merge(LIST_FIRST_NODE(&left), middle, LIST_FIRST_NODE(&right), size - middle, &merged, func);
LIST_FIRST_NODE(head) = LIST_FIRST_NODE(&merged);
}
static void merge(n2n_list_node_t *left, size_t left_size,
n2n_list_node_t *right, size_t right_size,
n2n_list_head_t *merged,
cmp_func_t cmp)
{
n2n_list_node_t *last_added = &merged->node;
while (left_size > 0 && right_size > 0)
{
if (cmp(left, right) <= 0)
{
last_added->next = left;
last_added = left;
left = left->next;
left_size--;
}
else
{
last_added->next = right;
last_added = right;
right = right->next;
right_size--;
}
}
if (left_size > 0)
{
last_added->next = left;
}
else if (right_size > 0)
{
last_added->next = right;
}
}
void list_sort(n2n_list_head_t *head, cmp_func_t func)
{
size_t size = list_size(head);
merge_sort(head, size, func);
}
/********************************************/
#include <fcntl.h>//TODO remove after fixing file open
static FILE *open_list_file_for_read(const char *filename)
{
#if defined(WIN32)
FILE *f = fopen(filename, "a+");
fseek(f, 0L, SEEK_SET);
return f;
#else//TODO remove
int fd = open(filename, O_CREAT | O_RDONLY, 0666);
if (fd < 0)
return NULL;
return fdopen(fd, "r");
#endif
}
int read_list_from_file(const char *filename, n2n_list_head_t *head, rd_entry_func_t rd_entry_func)
{
FILE *f = NULL;
n2n_list_node_t *new_item = NULL;
traceInfo("opening file %s for reading", filename);
f = open_list_file_for_read(filename);
if (!f)
{
traceError("couldn't open file. %s", strerror(errno));
return -1;
}
while ((new_item = rd_entry_func(f)) != NULL)
{
list_add(head, new_item);
}
list_reverse(head);
fclose(f);
return 0;
out_err:
list_clear(head);
fclose(f);
return -1;
}
int write_list_to_file(const char *filename, n2n_list_head_t *head, wr_entry_func_t wr_entry_func)
{
n2n_list_node_t *node;
FILE *f = fopen(filename, "w");
if (!f)
{
traceError("couldn't open community file");
return -1;
}
LIST_FOR_EACH_NODE(head, node)
{
wr_entry_func(f, node);
}
fclose(f);
return 0;
out_err:
fclose(f);
return -1;
}