LXR toybox/lib/llist.c

   1/* llist.c - Linked list functions
   2 *
   3 * Linked list structures have a next pointer as their first element.
   4 */
   5
   6#include "toys.h"
   7
   8// Callback function to free data pointer of double_list or arg_list
   9
  10void llist_free_arg(void *node)
  11{
  12  struct arg_list *d = node;
  13
  14  free(d->arg);
  15  free(d);
  16}
  17
  18void llist_free_double(void *node)
  19{
  20  struct double_list *d = node;
  21
  22  free(d->data);
  23  free(d);
  24}
  25
  26// Call a function (such as free()) on each element of a linked list.
  27void llist_traverse(void *list, void (*using)(void *node))
  28{
  29  void *old = list;
  30
  31  while (list) {
  32    void *pop = llist_pop(&list);
  33    using(pop);
  34
  35    // End doubly linked list too.
  36    if (old == list) break;
  37  }
  38}
  39
  40// Return the first item from the list, advancing the list (which must be called
  41// as &list)
  42void *llist_pop(void *list)
  43{
  44  // I'd use a void ** for the argument, and even accept the typecast in all
  45  // callers as documentation you need the &, except the stupid compiler
  46  // would then scream about type-punned pointers.  Screw it.
  47  void **llist = (void **)list;
  48  void **next = (void **)*llist;
  49  *llist = *next;
  50
  51  return (void *)next;
  52}
  53
  54void *dlist_pop(void *list)
  55{
  56  struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;
  57
  58  if (dlist->next == dlist) *pdlist = 0;
  59  else {
  60    dlist->next->prev = dlist->prev;
  61    dlist->prev->next = *pdlist = dlist->next;
  62  }
  63
  64  return dlist;
  65}
  66
  67void dlist_add_nomalloc(struct double_list **list, struct double_list *new)
  68{
  69  if (*list) {
  70    new->next = *list;
  71    new->prev = (*list)->prev;
  72    (*list)->prev->next = new;
  73    (*list)->prev = new;
  74  } else *list = new->next = new->prev = new;
  75}
  76
  77
  78// Add an entry to the end of a doubly linked list
  79struct double_list *dlist_add(struct double_list **list, char *data)
  80{
  81  struct double_list *new = xmalloc(sizeof(struct double_list));
  82
  83  new->data = data;
  84  dlist_add_nomalloc(list, new);
  85
  86  return new;
  87}
  88
  89// Terminate circular list for traversal in either direction. Returns end *.
  90void *dlist_terminate(void *list)
  91{
  92  struct double_list *end = list;
  93
  94  if (!list) return 0;
  95
  96  end = end->prev;
  97  end->next->prev = 0;
  98  end->next = 0;
  99
 100  return end;
 101}
 102
 103// Find num in cache
 104struct num_cache *get_num_cache(struct num_cache *cache, long long num)
 105{
 106  while (cache) {
 107    if (num==cache->num) return cache;
 108    cache = cache->next;
 109  }
 110
 111  return 0;
 112}
 113
 114// Uniquely add num+data to cache. Updates *cache, returns pointer to existing
 115// entry if it was already there.
 116struct num_cache *add_num_cache(struct num_cache **cache, long long num,
 117  void *data, int len)
 118{
 119  struct num_cache *old = get_num_cache(*cache, num);
 120
 121  if (old) return old;
 122
 123  old = xzalloc(sizeof(struct num_cache)+len);
 124  old->next = *cache;
 125  old->num = num;
 126  memcpy(old->data, data, len);
 127  *cache = old;
 128
 129  return 0;
 130}
 131