/**
* Allocates a pbuf.
*
* The actual memory allocated for the pbuf is determined by the
* layer at which the pbuf is allocated and the requested size
* (from the size parameter).
*
* @param flag this parameter decides how and where the pbuf
* should be allocated as follows:
*
* - PBUF_RAM: buffer memory for pbuf is allocated as one large
* chunk. This includes protocol headers as well.
* - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
* protocol headers. Additional headers must be prepended
* by allocating another pbuf and chain in to the front of
* the ROM pbuf. It is assumed that the memory used is really
* similar to ROM in that it is immutable and will not be
* changed. Memory which is dynamic should generally not
* be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
* - PBUF_REF: no buffer memory is allocated for the pbuf, even for
* protocol headers. It is assumed that the pbuf is only
* being used in a single thread. If the pbuf gets queued,
* then pbuf_take should be called to copy the buffer.
* - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
* the pbuf pool that is allocated during pbuf_init().
*
* @return the allocated pbuf. If multiple pbufs where allocated, this
* is the first pbuf of a pbuf chain.
*/
struct pbuf *
pbuf_alloc(pbuf_layer l, u16_t length, pbuf_flag flag)
{
struct pbuf *p, *q, *r;
u16_t offset;
s32_t rem_len; /* remaining length */
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%u)\n", length));
/* determine header offset */
offset = 0;
switch (l) {
case PBUF_TRANSPORT:
/* add room for transport (often TCP) layer header */
offset += PBUF_TRANSPORT_HLEN;
/* FALLTHROUGH */
case PBUF_IP:
/* add room for IP layer header */
offset += PBUF_IP_HLEN;
/* FALLTHROUGH */
case PBUF_LINK:
/* add room for link layer header */
offset += PBUF_LINK_HLEN;
break;
case PBUF_RAW:
break;
default:
LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
return NULL;
}
switch (flag) {
case PBUF_POOL:
/* allocate head of pbuf chain into p */
p = pbuf_pool_alloc();
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
if (p == NULL) {
#if PBUF_STATS
++lwip_stats.pbuf.err;
#endif /* PBUF_STATS */
return NULL;
}
p->next = NULL;
/* make the payload pointer point 'offset' bytes into pbuf data memory */
p->payload = MEM_ALIGN((void *)((u8_t *)p + (sizeof(struct pbuf) + offset)));
LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
/* the total length of the pbuf chain is the requested size */
p->tot_len = length;
/* set the length of the first pbuf in the chain */
p->len = length > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: length;
/* set reference count (needed here in case we fail) */
p->ref = 1;
/* now allocate the tail of the pbuf chain */
/* remember first pbuf for linkage in next iteration */
r = p;
/* remaining length to be allocated */
rem_len = length - p->len;
/* any remaining pbufs to be allocated? */
while (rem_len > 0) {
q = pbuf_pool_alloc();
if (q == NULL) {
LWIP_DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n"));
#if PBUF_STATS
++lwip_stats.pbuf.err;
#endif /* PBUF_STATS */
/* free chain so far allocated */
pbuf_free(p);
/* bail out unsuccesfully */
return NULL;
}
q->next = NULL;
/* make previous pbuf point to this pbuf */
r->next = q;
/* set total length of this pbuf and next in chain */
q->tot_len = rem_len;
/* this pbuf length is pool size, unless smaller sized tail */
q->len = rem_len > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rem_len;
q->payload = (void *)((u8_t *)q + sizeof(struct pbuf));
LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
q->ref = 1;
/* calculate remaining length to be allocated */
rem_len -= q->len;
/* remember this pbuf for linkage in next iteration */
r = q;
}
/* end of chain */
/*r->next = NULL;*/
break;
case PBUF_RAM:
/* If pbuf is to be allocated in RAM, allocate memory for it. */
p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + offset) + MEM_ALIGN_SIZE(length));
if (p == NULL) {
return NULL;
}
/* Set up internal structure of the pbuf. */
p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf) + offset));
p->len = p->tot_len = length;
p->next = NULL;
p->flags = PBUF_FLAG_RAM;
LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
break;
/* pbuf references existing (static constant) ROM payload? */
case PBUF_ROM:
/* pbuf references existing (externally allocated) RAM payload? */
case PBUF_REF:
/* only allocate memory for the pbuf structure */
p = memp_malloc(MEMP_PBUF);
if (p == NULL) {
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n", flag == PBUF_ROM?"ROM":"REF"));
return NULL;
}
/* caller must set this field properly, afterwards */
p->payload = NULL;
p->len = p->tot_len = length;
p->next = NULL;
p->flags = (flag == PBUF_ROM? PBUF_FLAG_ROM: PBUF_FLAG_REF);
break;
default:
LWIP_ASSERT("pbuf_alloc: erroneous flag", 0);
return NULL;
}
/* set reference count */
p->ref = 1;
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%u) == %p\n", length, (void *)p));
return p;
}
/*-----------------------------------------------------------------------------------*/
struct pbuf *
pbuf_alloc(pbuf_layer l, uint16_t size, pbuf_flag flag)
{
struct pbuf *p, *q, *r;
uint16_t offset;
int32_t rsize;
offset = 0;
switch(l) {
case PBUF_TRANSPORT:
offset += PBUF_TRANSPORT_HLEN;
/* FALLTHROUGH */
case PBUF_IP:
offset += PBUF_IP_HLEN;
offset += PBUF_LINK_HLEN;
/* FALLTHROUGH */
case PBUF_LINK:
break;
case PBUF_RAW:
break;
default:
ASSERT("pbuf_alloc: bad pbuf layer", 0);
return NULL;
}
switch(flag)
{
case PBUF_POOL:
/* Allocate head of pbuf chain into p. */
p = pbuf_pool_alloc();
if(p == NULL) {
#ifdef PBUF_STATS
++stats.pbuf.err;
#endif /* PBUF_STATS */
return NULL;
}
p->next = NULL;
/* Set the payload pointer so that it points offset bytes into
pbuf data memory. */
p->payload = MEM_ALIGN((void *)((uint8_t *)p + (sizeof(struct pbuf) + offset)));
/* The total length of the pbuf is the requested size. */
p->tot_len = size;
/* Set the length of the first pbuf is the chain. */
p->len = size > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: size;
p->flags = PBUF_FLAG_POOL;
/* Allocate the tail of the pbuf chain. */
r = p;
rsize = size - p->len;
while(rsize > 0) {
q = pbuf_pool_alloc();
if(q == NULL) {
DEBUGF(PBUF_DEBUG, ("pbuf_alloc: Out of pbufs in pool,\n"));
#ifdef PBUF_STATS
++stats.pbuf.err;
#endif /* PBUF_STATS */
pbuf_pool_free(p);
return NULL;
}
q->next = NULL;
r->next = q;
q->len = rsize > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rsize;
q->flags = PBUF_FLAG_POOL;
q->payload = (void *)((uint8_t *)q + sizeof(struct pbuf));
r = q;
q->ref = 1;
q = q->next;
rsize -= PBUF_POOL_BUFSIZE;
}
r->next = NULL;
ASSERT("pbuf_alloc: pbuf->payload properly aligned",
((uint32_t)p->payload % MEM_ALIGNMENT) == 0);
break;
case PBUF_RAM:
/* If pbuf is to be allocated in RAM, allocate memory for it. */
p = (struct pbuf*)mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + size + offset));
if(p == NULL)
{ return NULL; }
/* Set up internal structure of the pbuf. */
p->payload = MEM_ALIGN((void *)((uint8_t *)p + sizeof(struct pbuf) + offset));
p->len = p->tot_len = size;
p->next = NULL;
p->flags = PBUF_FLAG_RAM;
ASSERT("pbuf_alloc: pbuf->payload properly aligned",
((uint32_t)p->payload % MEM_ALIGNMENT) == 0);
break;
case PBUF_ROM:
/* If the pbuf should point to ROM, we only need to allocate
memory for the pbuf structure. */
p = (struct pbuf*)memp_mallocp(MEMP_PBUF);
if(p == NULL) {
return NULL;
}
p->payload = NULL;
p->len = p->tot_len = size;
p->next = NULL;
p->flags = PBUF_FLAG_ROM;
break;
default:
ASSERT("pbuf_alloc: erroneous flag", 0);
return NULL;
}
p->ref = 1;
return p;
}
