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/*
** GNU Pth - The GNU Portable Threads
** Copyright (c) 1999 Ralf S. Engelschall <rse@engelschall.com>
**
** This file is part of GNU Pth, a non-preemptive thread scheduling
** library which can be found at http://www.gnu.org/software/pth/.
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2.1 of the License, or (at your option) any later version.
**
** This library is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
** Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
** USA, or contact Ralf S. Engelschall <rse@engelschall.com>.
**
** pth_ring.c: Pth ring data structure
*/
/* ``Unix was not designed to stop people
from doing stupid things, because that
would also stop them from doing clever
things.'' --Doug Gwyn */
#include "pth_p.h"
intern void pth_ring_init(pth_ring_t *r, pth_ringnode_t *rn)
{
if (r != NULL)
r->rn_hook = NULL;
if (rn != NULL) {
rn->rn_next = rn;
rn->rn_prev = rn;
}
return;
}
intern int pth_ring_empty(pth_ring_t *r)
{
if (r == NULL)
return FALSE;
return (r->rn_hook == NULL ? TRUE : FALSE);
}
intern int pth_ring_elements(pth_ring_t *r)
{
int n;
pth_ringnode_t *rn;
if (r == NULL)
return -1;
n = 0;
rn = r->rn_hook;
if (rn != NULL) {
do {
n++;
rn = rn->rn_next;
} while (rn != r->rn_hook);
}
return n;
}
#if cpp
#define pth_ring_next(r, rn) \
(((r) == NULL || (rn) == NULL) ? NULL : (rn)->rn_next)
#endif
#if cpp
#define pth_ring_prev(r, rn) \
(((r) == NULL || (rn) == NULL) ? NULL : (rn)->rn_prev)
#endif
#if cpp
#define pth_ring_first(r) \
((r) == NULL ? NULL : (r)->rn_hook)
#endif
intern pth_ringnode_t *pth_ring_last(pth_ring_t *r)
{
if (r == NULL)
return NULL;
if (r->rn_hook == NULL)
return NULL;
return r->rn_hook->rn_prev;
}
intern void pth_ring_insert_after(pth_ring_t *r, pth_ringnode_t *rn1, pth_ringnode_t *rn2)
{
if (r == NULL || rn1 == NULL || rn2 == NULL)
return;
rn2->rn_prev = rn1;
rn2->rn_next = rn1->rn_next;
rn2->rn_prev->rn_next = rn2;
rn2->rn_next->rn_prev = rn2;
return;
}
intern void pth_ring_insert_before(pth_ring_t *r, pth_ringnode_t *rn1, pth_ringnode_t *rn2)
{
if (r == NULL || rn1 == NULL || rn2 == NULL)
return;
rn2->rn_next = rn1;
rn2->rn_prev = rn1->rn_prev;
rn2->rn_prev->rn_next = rn2;
rn2->rn_next->rn_prev = rn2;
return;
}
intern void pth_ring_remove(pth_ring_t *r, pth_ringnode_t *rn)
{
if (r == NULL || rn == NULL)
return;
if (r->rn_hook == rn && rn->rn_prev == rn && rn->rn_next == rn)
r->rn_hook = NULL;
else {
if (r->rn_hook == rn)
r->rn_hook = rn->rn_next;
rn->rn_prev->rn_next = rn->rn_next;
rn->rn_next->rn_prev = rn->rn_prev;
}
rn->rn_next = rn;
rn->rn_prev = rn;
return;
}
intern void pth_ring_prepend(pth_ring_t *r, pth_ringnode_t *rn)
{
if (r == NULL || rn == NULL)
return;
if (r->rn_hook == NULL) {
r->rn_hook = rn;
rn->rn_next = rn;
rn->rn_prev = rn;
}
else {
rn->rn_next = r->rn_hook;
rn->rn_prev = r->rn_hook->rn_prev;
rn->rn_next->rn_prev = rn;
rn->rn_prev->rn_next = rn;
r->rn_hook = rn;
}
return;
}
intern void pth_ring_append(pth_ring_t *r, pth_ringnode_t *rn)
{
if (r == NULL || rn == NULL)
return;
if (r->rn_hook == NULL) {
r->rn_hook = rn;
rn->rn_next = rn;
rn->rn_prev = rn;
}
else {
rn->rn_next = r->rn_hook;
rn->rn_prev = r->rn_hook->rn_prev;
rn->rn_next->rn_prev = rn;
rn->rn_prev->rn_next = rn;
}
return;
}
#if cpp
#define pth_ring_push(r, rn) \
pth_ring_prepend((r), (rn))
#endif
#if cpp
#define pth_ring_unshift(r, rn) \
pth_ring_append((r), (rn))
#endif
intern pth_ringnode_t *pth_ring_pop(pth_ring_t *r)
{
pth_ringnode_t *rn;
rn = pth_ring_first(r);
if (rn != NULL)
pth_ring_remove(r, rn);
return rn;
}
intern pth_ringnode_t *pth_ring_shift(pth_ring_t *r)
{
pth_ringnode_t *rn;
rn = pth_ring_last(r);
if (rn != NULL)
pth_ring_remove(r, rn);
return rn;
}
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