/*-----------------------------------------------------------------------------------*/
uint8_t
pbuf_free(struct pbuf *p)
{
struct pbuf *q;
uint8_t count = 0;
if(p == NULL) {
return 0;
}
ASSERT("pbuf_free: sane flags", p->flags == PBUF_FLAG_POOL ||
p->flags == PBUF_FLAG_ROM ||
p->flags == PBUF_FLAG_RAM);
ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
/* Decrement reference count. */
p->ref--;
q = NULL;
/* If reference count == 0, actually deallocate pbuf. */
if(p->ref == 0) {
while(p != NULL) {
/* Check if this is a pbuf from the pool. */
if(p->flags == PBUF_FLAG_POOL) {
p->len = p->tot_len = PBUF_POOL_BUFSIZE;
p->payload = (void *)((uint8_t *)p + sizeof(struct pbuf));
q = p->next;
PBUF_POOL_FREE(p);
#ifdef PBUF_STATS
--stats.pbuf.used;
#endif /* PBUF_STATS */
} else if(p->flags == PBUF_FLAG_ROM) {
q = p->next;
memp_freep(MEMP_PBUF, p);
} else {
q = p->next;
mem_free(p);
}
p = q;
count++;
}
pbuf_refresh();
}
return count;
}
/**
* Dereference a pbuf chain or queue and deallocate any no-longer-used
* pbufs at the head of this chain or queue.
*
* Decrements the pbuf reference count. If it reaches zero, the pbuf is
* deallocated.
*
* For a pbuf chain, this is repeated for each pbuf in the chain,
* up to the first pbuf which has a non-zero reference count after
* decrementing. So, when all reference counts are one, the whole
* chain is free'd.
*
* @param pbuf The pbuf (chain) to be dereferenced.
*
* @return the number of pbufs that were de-allocated
* from the head of the chain.
*
* @note MUST NOT be called on a packet queue (Not verified to work yet).
* @note the reference counter of a pbuf equals the number of pointers
* that refer to the pbuf (or into the pbuf).
*
* @internal examples:
*
* Assuming existing chains a->b->c with the following reference
* counts, calling pbuf_free(a) results in:
*
* 1->2->3 becomes ...1->3
* 3->3->3 becomes 2->3->3
* 1->1->2 becomes ......1
* 2->1->1 becomes 1->1->1
* 1->1->1 becomes .......
*
*/
u8_t
pbuf_free(struct pbuf *p)
{
struct pbuf *q;
u8_t count;
SYS_ARCH_DECL_PROTECT(old_level);
LWIP_ASSERT("p != NULL", p != NULL);
/* if assertions are disabled, proceed with debug output */
if (p == NULL) {
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n"));
return 0;
}
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_free(%p)\n", (void *)p));
PERF_START;
LWIP_ASSERT("pbuf_free: sane flags",
p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_ROM ||
p->flags == PBUF_FLAG_REF || p->flags == PBUF_FLAG_POOL);
count = 0;
/* Since decrementing ref cannot be guaranteed to be a single machine operation
* we must protect it. Also, the later test of ref must be protected.
*/
SYS_ARCH_PROTECT(old_level);
/* de-allocate all consecutive pbufs from the head of the chain that
* obtain a zero reference count after decrementing*/
while (p != NULL) {
/* all pbufs in a chain are referenced at least once */
LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
/* decrease reference count (number of pointers to pbuf) */
p->ref--;
/* this pbuf is no longer referenced to? */
if (p->ref == 0) {
/* remember next pbuf in chain for next iteration */
q = p->next;
LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: deallocating %p\n", (void *)p));
/* is this a pbuf from the pool? */
if (p->flags == PBUF_FLAG_POOL) {
p->len = p->tot_len = PBUF_POOL_BUFSIZE;
p->payload = (void *)((u8_t *)p + sizeof(struct pbuf));
PBUF_POOL_FREE(p);
/* is this a ROM or RAM referencing pbuf? */
} else if (p->flags == PBUF_FLAG_ROM || p->flags == PBUF_FLAG_REF) {
memp_free(MEMP_PBUF, p);
/* p->flags == PBUF_FLAG_RAM */
} else {
mem_free(p);
}
count++;
/* proceed to next pbuf */
p = q;
/* p->ref > 0, this pbuf is still referenced to */
/* (and so the remaining pbufs in chain as well) */
} else {
LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: %p has ref %u, ending here.\n", (void *)p, (unsigned int)p->ref));
/* stop walking through the chain */
p = NULL;
}
}
SYS_ARCH_UNPROTECT(old_level);
PERF_STOP("pbuf_free");
/* return number of de-allocated pbufs */
return count;
}
/*-----------------------------------------------------------------------------------*/
void
pbuf_realloc(struct pbuf *p, uint16_t size)
{
struct pbuf *q, *r;
uint16_t rsize;
ASSERT("pbuf_realloc: sane p->flags", p->flags == PBUF_FLAG_POOL ||
p->flags == PBUF_FLAG_ROM ||
p->flags == PBUF_FLAG_RAM);
if(p->tot_len <= size) {
return;
}
switch(p->flags) {
case PBUF_FLAG_POOL:
/* First, step over any pbufs that should still be in the chain. */
rsize = size;
q = p;
while(rsize > q->len) {
rsize -= q->len;
q = q->next;
}
/* Adjust the length of the pbuf that will be halved. */
q->len = rsize;
/* And deallocate any left over pbufs. */
r = q->next;
q->next = NULL;
q = r;
while(q != NULL) {
r = q->next;
PBUF_POOL_FREE(q);
#ifdef PBUF_STATS
--stats.pbuf.used;
#endif /* PBUF_STATS */
q = r;
}
break;
case PBUF_FLAG_ROM:
p->len = size;
break;
case PBUF_FLAG_RAM:
/* First, step over the pbufs that should still be in the chain. */
rsize = size;
q = p;
while(rsize > q->len) {
rsize -= q->len;
q = q->next;
}
if(q->flags == PBUF_FLAG_RAM) {
/* Reallocate and adjust the length of the pbuf that will be halved. */
mem_realloc(q, (uint8_t *)q->payload - (uint8_t *)q + rsize);
}
q->len = rsize;
/* And deallocate any left over pbufs. */
r = q->next;
q->next = NULL;
q = r;
while(q != NULL) {
r = q->next;
pbuf_free(q);
q = r;
}
break;
}
p->tot_len = size;
pbuf_refresh();
}
