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/*
* BIRD Library -- Safe Linked Lists
*
* (c) 1998 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#define _BIRD_SLISTS_C_
#include "nest/bird.h"
#include "lib/slists.h"
static inline void
s_merge(snode *from, snode *to)
{
siterator *f, *g;
if (!(f = from->readers))
return;
if (!(g = to->readers))
{
/* Fast path */
to->readers = f;
f->prev = (siterator *) to;
fixup:
while (f && f->node)
{
f->node = NULL;
f = f->next;
}
return;
}
/* Really merging */
while (g->next)
g = g->next;
g->next = f;
f->prev = g;
goto fixup;
}
snode *
s_get(siterator *i)
{
siterator *f, *g;
snode *n;
if (!(n = i->node))
{
/*
* No node found. We have to walk the iterator list backwards
* to find where are we linked.
*/
f = i;
while (!f->null)
f = f->prev;
n = (snode *) f;
}
f = i->prev; /* Maybe the snode itself */
g = i->next;
f->next = g;
if (g)
g->prev = f;
i->prev = NULL;
i->next = NULL;
return n;
}
void
s_put(siterator *i, snode *n)
{
siterator *f;
i->node = n;
if (f = n->readers)
f->prev = i;
i->next = f;
n->readers = i;
i->prev = (siterator *) n;
i->null = NULL;
}
void
s_add_tail(slist *l, snode *n)
{
snode *z = l->tail;
n->next = (snode *) &l->null;
n->prev = z;
z->next = n;
l->tail = n;
n->readers = NULL;
}
void
s_add_head(slist *l, snode *n)
{
snode *z = l->head;
n->next = z;
n->prev = (snode *) &l->head;
z->prev = n;
l->head = n;
n->readers = NULL;
}
void
s_insert_node(snode *n, snode *after)
{
snode *z = after->next;
n->next = z;
n->prev = after;
after->next = n;
z->prev = n;
n->readers = NULL;
}
void
s_rem_node(snode *n)
{
snode *z = n->prev;
snode *x = n->next;
z->next = x;
x->prev = z;
s_merge(n, x);
}
void
s_init_list(slist *l)
{
l->head = (snode *) &l->null;
l->null = NULL;
l->tail = (snode *) &l->head;
l->tail_readers = NULL;
}
void
s_add_tail_list(slist *to, slist *l)
{
snode *p = to->tail;
snode *q = l->head;
p->next = q;
q->prev = p;
q = l->tail;
q->next = (snode *) &to->null;
to->tail = q;
s_merge((snode *) &l->null, (snode *) &to->null);
}
#ifdef TEST
#include "lib/resource.h"
#include <stdio.h>
void dump(char *c, slist *a)
{
snode *x;
puts(c);
for(x=SHEAD(*a); x; x=x->next)
{
siterator *i, *j;
printf("%p", x);
j = (siterator *) x;
for(i=x->readers; i; i=i->next)
{
if (i->prev != j)
printf(" ???");
j = i;
printf(" [%p:%p]", i, i->node);
}
putchar('\n');
}
puts("---");
}
int main(void)
{
slist a, b;
snode *x, *y;
siterator i, j;
s_init_list(&a);
s_init_list(&b);
x = xmalloc(sizeof(*x));
s_add_tail(&a, x);
x = xmalloc(sizeof(*x));
s_add_tail(&a, x);
x = xmalloc(sizeof(*x));
s_add_tail(&a, x);
dump("1", &a);
s_init(&i, &a);
s_init(&j, &a);
dump("2", &a);
x = s_get(&i);
printf("Got %p\n", x);
dump("3", &a);
s_put(&i, x->next);
dump("4", &a);
y = s_get(&j);
while (y)
{
s_put(&j, y);
dump("5*", &a);
y = s_get(&j)->next;
}
dump("5 done", &a);
s_rem_node(a.head->next);
dump("6 (deletion)", &a);
s_put(&i, s_get(&i)->next);
dump("6 (relink)", &a);
x = xmalloc(sizeof(*x));
s_add_tail(&b, x);
dump("7 (second list)", &b);
s_add_tail_list(&b, &a);
dump("8 (after merge)", &b);
return 0;
}
#endif
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