Revision 7c331b1ee58f504e2f77c8ec64224ad3b674463b authored by Ronny Lorenz on 04 May 2015, 13:34:30 UTC, committed by Ronny Lorenz on 04 May 2015, 13:34:30 UTC
1 parent fa00faf
list.c
/*
$Log: list.c,v $
Revision 1.5 2003/07/14 13:36:58 ivo
use space() instead of malloc
Revision 1.4 2000/10/10 08:53:52 ivo
include dmalloc.h header if DMALLOC defined
Revision 1.4 2000/10/10 08:04:34 ivo
include dmalloc header id DMALLOC defined
Revision 1.3 1998/03/30 14:24:51 ivo
use RNA package utils.h
Revision 1.2 1997/10/09 19:01:50 steve
*** empty log message ***
Revision 1.1 1997/08/04 21:05:32 walter
Initial revision
*/
/*
(C) 1991 Kendall Bennett.
*/
#include <stdio.h>
#include <stdlib.h>
#include "utils.h"
#include "list.h"
/*@unused@*/
static char rcsid[] = "$Id: list.c,v 1.5 2003/07/14 13:36:58 ivo Exp $";
#define PUBLIC
PUBLIC void *
lst_newnode (int size)
/****************************************************************************
*
* Function: lst_newnode
* Parameters: size - Amount of memory to allocate for node
* Returns: Pointer to the allocated node's user space.
*
* Description: Allocates the memory required for a node, adding a small
* header at the start of the node. We return a reference to
* the user space of the node, as if it had been allocated via
* malloc().
*
****************************************************************************/
{
LST_BUCKET *node;
node = (LST_BUCKET *) space (size + sizeof (LST_BUCKET));
return LST_USERSPACE (node); /* Return pointer to user space */
}
PUBLIC void
lst_freenode (void *node)
/****************************************************************************
*
* Function: lst_freenode
* Parameters: node - Node to free.
*
* Description: Frees a node previously allocated with lst_newnode().
*
****************************************************************************/
{
free (LST_HEADER (node));
}
PUBLIC LIST *
lst_init (void)
/****************************************************************************
*
* Function: lst_init
* Returns: Pointer to a newly created list.
*
* Description: Initialises a list and returns a pointer to it.
*
****************************************************************************/
{
LIST *l;
if ((l = (LIST *) space (sizeof (LIST))) != NULL)
{
l->count = 0;
l->head = &(l->hz[0]);
l->z = &(l->hz[1]);
l->head->next = l->z->next = l->z;
}
return l;
}
PUBLIC void
lst_kill (LIST * l, void (*freeNode) (void *node))
/****************************************************************************
*
* Function: lst_kill
* Parameters: l - List to kill
* freeNode - Pointer to user routine to free a node
*
* Description: Kills the list l, by deleting all of the elements contained
* within the list one by one and then deleting the list
* itself. Note that we call the user supplied routine
* (*freeNode)() to free each list node. This allows the user
* program to perform any extra processing needed to kill each
* node (if each node contains pointers to other items on the
* heap for example). If no extra processing is required, just
* pass the address of lst_freenode(), ie:
*
* lst_kill(myList,lst_freenode);
*
****************************************************************************/
{
LST_BUCKET *n, *p;
n = l->head->next;
while (n != l->z)
{ /* Free all nodes in list */
p = n;
n = n->next;
(*freeNode) (LST_USERSPACE (p));
}
free (l); /* Free the list itself */
}
PUBLIC void
lst_insertafter (LIST * l, void *node, void *after)
/****************************************************************************
*
* Function: lst_insertafter
* Parameters: l - List to insert node into
* node - Pointer to user space of node to insert
* after - Pointer to user space of node to insert node after
*
* Description: Inserts a new node into the list after the node 'after'. To
* insert a new node at the beginning of the list, user the
* macro LST_HEAD in place of 'after'. ie:
*
* lst_insertafter(mylist,node,LST_HEAD(mylist));
*
****************************************************************************/
{
LST_BUCKET *n = LST_HEADER (node), *a = LST_HEADER (after);
n->next = a->next;
a->next = n;
l->count++;
}
PUBLIC void *
lst_deletenext (LIST * l, void *node)
/****************************************************************************
*
* Function: lst_deletenext
* Parameters: l - List to delete node from.
* node - Node to delete the next node from
* Returns: Pointer to the deleted node's userspace.
*
* Description: Removes the node AFTER 'node' from the list l.
*
****************************************************************************/
{
LST_BUCKET *n = LST_HEADER (node);
node = LST_USERSPACE (n->next);
n->next = n->next->next;
l->count--;
return node;
}
PUBLIC void *
lst_first (LIST * l)
/****************************************************************************
*
* Function: lst_first
* Parameters: l - List to obtain first node from
* Returns: Pointer to first node in list, NULL if list is empty.
*
* Description: Returns a pointer to the user space of the first node in
* the list. If the list is empty, we return NULL.
*
****************************************************************************/
{
LST_BUCKET *n;
n = l->head->next;
return (n == l->z ? NULL : LST_USERSPACE (n));
}
PUBLIC void *
lst_next (void *prev)
/****************************************************************************
*
* Function: lst_next
* Parameters: prev - Previous node in list to obtain next node from
* Returns: Pointer to the next node in the list, NULL at end of list.
*
* Description: Returns a pointer to the user space of the next node in the
* list given a pointer to the user space of the previous node.
* If we have reached the end of the list, we return NULL. The
* end of the list is detected when the next pointer of a node
* points back to itself, as does the dummy last node's next
* pointer. This enables us to detect the end of the list
* without needed access to the list data structure itself.
*
* NOTE: We do no checking to ensure that 'prev' is NOT a
* NULL pointer.
*
****************************************************************************/
{
LST_BUCKET *n = LST_HEADER (prev);
n = n->next;
return (n == n->next ? NULL : LST_USERSPACE (n));
}
/* Static globals required by merge() */
static LST_BUCKET *z;
static int (*cmp) (void *, void *);
static LST_BUCKET *
merge (LST_BUCKET * a, LST_BUCKET * b, LST_BUCKET ** end)
/****************************************************************************
*
* Function: merge
* Parameters: a,b - Sublist's to merge
* Returns: Pointer to the merged sublists.
*
* Description: Merges two sorted lists of nodes together into a single
* sorted list.
*
****************************************************************************/
{
LST_BUCKET *c;
/* Go through the lists, merging them together in sorted order */
c = z;
while (a != z && b != z)
{
if ((*cmp) (LST_USERSPACE (a), LST_USERSPACE (b)) <= 0)
{
c->next = a;
c = a;
a = a->next;
}
else
{
c->next = b;
c = b;
b = b->next;
}
};
/* If one of the lists is not exhausted, then re-attach it to the end
* of the newly merged list
*/
if (a != z)
c->next = a;
if (b != z)
c->next = b;
/* Set *end to point to the end of the newly merged list */
while (c->next != z)
c = c->next;
*end = c;
/* Determine the start of the merged lists, and reset z to point to
* itself
*/
c = z->next;
z->next = z;
return c;
}
PUBLIC void
lst_mergesort (LIST * l, int (*cmp_func) (void *, void *))
/****************************************************************************
*
* Function: lst_mergesort
* Parameters: l - List to merge sort
* cmp_func - Function to compare two user spaces
*
* Description: Mergesort's all the nodes in the list. 'cmp' must point to
* a comparison function that can compare the user spaces of
* two different nodes. 'cmp' should work the same as
* strcmp(), in terms of the values it returns.
*
****************************************************************************/
{
int i, N;
LST_BUCKET *a, *b; /* Pointers to sublists to merge */
LST_BUCKET *c; /* Pointer to end of sorted sublists */
LST_BUCKET *head; /* Pointer to dummy head node for list */
LST_BUCKET *todo; /* Pointer to sublists yet to be sorted */
LST_BUCKET *t; /* Temporary */
/* Set up globals required by merge() and pointer to head */
z = l->z;
cmp = cmp_func;
head = l->head;
for (N = 1, a = z; a != head->next; N = N + N)
{
todo = head->next;
c = head;
while (todo != z)
{
/* Build first sublist to be merged, and splice from main list
*/
a = t = todo;
for (i = 1; i < N; i++)
t = t->next;
b = t->next;
t->next = z;
t = b;
/* Build second sublist to be merged and splice from main list
*/
for (i = 1; i < N; i++)
t = t->next;
todo = t->next;
t->next = z;
/* Merge the two sublists created, and set 'c' to point to the
* end of the newly merged sublists.
*/
c->next = merge (a, b, &t);
c = t;
}
}
}
#ifdef LIST_TEST
/*---------------------------------------------------------------*/
/*---------------------------------------------------------------*/
/* Simple program to test the list routines */
typedef struct
{
char name[40];
int age;
}
REC;
/*---------------------------------------------------------------*/
int
my_cmp (REC * r1, REC * r2)
{
return strcmp (r1->name, r2->name);
}
/*---------------------------------------------------------------*/
void
main (void)
{
LIST *list;
int done = 0;
REC *rec;
char line[80];
list = lst_init ();
printf ("Type a list of names and ages. Empty line quits\n\n");
while (!done)
{
rec = lst_newnode (sizeof (REC));
gets (line);
if ((done = (line[0] == '\0')) != 1)
{
strcpy (rec->name, line);
gets (line);
rec->age = atoi (line);
lst_insertafter (list, rec, LST_HEAD (list));
}
};
printf ("\nThe list you typed in was:\n\n");
for (rec = lst_first (list); rec; rec = lst_next (rec))
printf ("Name: %s, Age: %d\n", rec->name, rec->age);
printf ("\nSorting the list...\n\n");
lst_mergesort (list, my_cmp);
for (rec = lst_first (list); rec; rec = lst_next (rec))
printf ("Name: %s, Age: %d\n", rec->name, rec->age);
lst_kill (list, lst_freenode);
}
/*---------------------------------------------------------------*/
#endif
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