pbuf.h File Reference

#include "arch/cc.h"

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Data Structures
struct	pbuf
Defines
#define	PBUF_TRANSPORT_HLEN   20
#define	PBUF_IP_HLEN   20
#define	PBUF_FLAG_RAM   0x00
#define	PBUF_FLAG_ROM   0x01
#define	PBUF_FLAG_POOL   0x02
#define	PBUF_FLAG_REF   0x04
Enumerations
enum	pbuf_layer { PBUF_TRANSPORT, PBUF_IP, PBUF_LINK, PBUF_RAW }
enum	pbuf_flag { PBUF_RAM, PBUF_ROM, PBUF_REF, PBUF_POOL }
Functions
void	pbuf_init (void)
pbuf *	pbuf_alloc (pbuf_layer l, u16_t size, pbuf_flag flag)
void	pbuf_realloc (struct pbuf *p, u16_t size)
u8_t	pbuf_header (struct pbuf *p, s16_t header_size)
void	pbuf_ref (struct pbuf *p)
void	pbuf_ref_chain (struct pbuf *p)
u8_t	pbuf_free (struct pbuf *p)
u8_t	pbuf_clen (struct pbuf *p)
void	pbuf_chain (struct pbuf *h, struct pbuf *t)
pbuf *	pbuf_dechain (struct pbuf *p)
pbuf *	pbuf_take (struct pbuf *f)

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Define Documentation

#define PBUF_FLAG_POOL   0x02

Definition at line 60 of file pbuf.h. Referenced by pbuf_alloc(), pbuf_free(), pbuf_header(), and pbuf_realloc().

#define PBUF_FLAG_RAM   0x00

Definition at line 58 of file pbuf.h. Referenced by pbuf_alloc(), pbuf_free(), pbuf_header(), and pbuf_realloc().

#define PBUF_FLAG_REF   0x04

Definition at line 61 of file pbuf.h. Referenced by pbuf_alloc(), pbuf_free(), pbuf_header(), pbuf_realloc(), and pbuf_take().

#define PBUF_FLAG_ROM   0x01

Definition at line 59 of file pbuf.h. Referenced by pbuf_alloc(), pbuf_free(), pbuf_header(), and pbuf_realloc().

#define PBUF_IP_HLEN   20

Definition at line 40 of file pbuf.h. Referenced by pbuf_alloc().

#define PBUF_TRANSPORT_HLEN   20

Definition at line 39 of file pbuf.h. Referenced by pbuf_alloc().

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Enumeration Type Documentation

enum pbuf_flag

Enumeration values: PBUF_RAM  PBUF_ROM  PBUF_REF  PBUF_POOL  Definition at line 49 of file pbuf.h. { PBUF_RAM, PBUF_ROM, PBUF_REF, PBUF_POOL } pbuf_flag;

enum pbuf_layer

Enumeration values: PBUF_TRANSPORT  PBUF_IP  PBUF_LINK  PBUF_RAW  Definition at line 42 of file pbuf.h. { PBUF_TRANSPORT, PBUF_IP, PBUF_LINK, PBUF_RAW } pbuf_layer;

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Function Documentation

struct pbuf* pbuf_alloc (  pbuf_layer  l, u16_t  length, pbuf_flag  flag )

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). Parameters: 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(). Returns: the allocated pbuf. If multiple pbufs where allocated, this is the first pbuf of a pbuf chain. Definition at line 231 of file pbuf.c. References DBG_TRACE, DEBUGF, LWIP_ASSERT, MEM_ALIGN, MEM_ALIGN_SIZE, mem_malloc(), memp_mallocp(), MEMP_PBUF, NULL, PBUF_DEBUG, PBUF_FLAG_POOL, PBUF_FLAG_RAM, PBUF_FLAG_REF, PBUF_FLAG_ROM, PBUF_IP, PBUF_IP_HLEN, PBUF_LINK, PBUF_POOL, pbuf_pool_alloc(), pbuf_pool_free(), PBUF_RAM, PBUF_RAW, PBUF_REF, PBUF_ROM, PBUF_TRANSPORT, PBUF_TRANSPORT_HLEN, s32_t, u16_t, u32_t, and u8_t. Referenced by arp_query(), dhcp_create_request(), etharp_query(), icmp_dest_unreach(), icmp_time_exceeded(), ip_frag(), ip_reass(), loopif_output(), netbuf_alloc(), netbuf_ref(), pbuf_take(), rt_3com905cif_low_level_input(), rt_rtl8139if_low_level_input(), and slipif_input(). { struct pbuf *p, *q, *r; u16_t offset; s32_t rem_len; /* remaining 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(); if (p == NULL) { #ifdef 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", ((u32_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 pbuf type */ p->flags = PBUF_FLAG_POOL; /* 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) { DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n")); #ifdef PBUF_STATS ++lwip_stats.pbuf.err; #endif /* PBUF_STATS */ /* bail out unsuccesfully */ pbuf_pool_free(p); return NULL; } //q->next = NULL; /* make previous pbuf point to this pbuf */ r->next = q; /* set length of this pbuf */ q->len = rem_len > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rem_len; q->flags = PBUF_FLAG_POOL; q->payload = (void *)((u8_t *)q + sizeof(struct pbuf)); LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned", ((u32_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) + length + offset)); 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", ((u32_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_mallocp(MEMP_PBUF); if (p == NULL) { DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_REF.\n")); 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; } p->ref = 1; return p; }

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void pbuf_chain (  struct pbuf *  h, struct pbuf *  t )

Link two pbufs (or chains) together. Parameters: h  head pbuf (chain) t  tail pbuf (chain) The ->tot_len field of the first pbuf (h) is adjusted. Definition at line 719 of file pbuf.c. References DBG_FRESH, DEBUGF, LWIP_ASSERT, pbuf::next, NULL, PBUF_DEBUG, pbuf_ref(), and pbuf::tot_len. Referenced by ip_frag(), netbuf_chain(), and slipif_input(). { struct pbuf *p; LWIP_ASSERT("h != NULL", h != NULL); LWIP_ASSERT("t != NULL", t != NULL); /* proceed to last pbuf of chain */ for (p = h; p->next != NULL; p = p->next) { /* add total length of second chain to all totals of first chain */ p->tot_len += t->tot_len; } /* p is last pbuf of first h chain */ /* add total length of second chain to last pbuf total of first chain */ p->tot_len += t->tot_len; /* chain last pbuf of h chain (p) with first of tail (t) */ p->next = t; /* t is now referenced to one more time */ pbuf_ref(t); DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_chain: referencing tail %p\n", (void *) t)); }

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u8_t pbuf_clen (  struct pbuf *  p  )

Count number of pbufs in a chain Parameters: p  first pbuf of chain Returns: the number of pbufs in a chain Definition at line 658 of file pbuf.c. References len, pbuf::next, NULL, and u8_t. { u8_t len; len = 0; while (p != NULL) { ++len; p = p->next; } return len; }

struct pbuf* pbuf_dechain (  struct pbuf *  p  )

Dechains the first pbuf from its succeeding pbufs in the chain. Makes p->tot_len field equal to p->len. Parameters: p  pbuf to dechain Returns: remainder of the pbuf chain, or NULL if it was de-allocated. Definition at line 749 of file pbuf.c. References DBG_STATE, DEBUGF, pbuf::len, LWIP_ASSERT, pbuf::next, NULL, PBUF_DEBUG, pbuf_free(), pbuf::tot_len, and u8_t. { struct pbuf *q; u8_t tail_gone = 1; /* tail */ q = p->next; /* pbuf has successor in chain? */ if (q != NULL) { /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */ LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len); /* enforce invariant if assertion is disabled */ q->tot_len = p->tot_len - p->len; /* decouple pbuf from remainder */ p->next = NULL; /* total length of pbuf p is its own length only */ p->tot_len = p->len; /* q is no longer referenced by p, free it */ DEBUGF(PBUF_DEBUG | DBG_STATE, ("pbuf_dechain: unreferencing %p\n", (void *) q)); tail_gone = pbuf_free(q); /* return remaining tail or NULL if deallocated */ } /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */ LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len); return (tail_gone > 0? NULL: q); }

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u8_t pbuf_free (  struct pbuf *  p  )

Free a pbuf (chain) from usage, de-allocate non-used head of chain. 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, until a non-zero reference count is encountered, or the end of the chain is reached. Parameters: pbuf  pbuf (chain) to be freed from one user. Returns: the number of unreferenced pbufs that were de-allocated from the head of the chain. Note: the reference counter of a pbuf equals the number of pointers that refer to the pbuf (or into the pbuf). For internal use only. examples: 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 ....... Definition at line 589 of file pbuf.c. References DBG_TRACE, DEBUGF, pbuf::flags, pbuf::len, LWIP_ASSERT, mem_free(), memp_freep(), MEMP_PBUF, pbuf::next, NULL, pbuf::payload, PBUF_DEBUG, PBUF_FLAG_POOL, PBUF_FLAG_RAM, PBUF_FLAG_REF, PBUF_FLAG_ROM, PBUF_POOL_FREE, pbuf_refresh(), pbuf::ref, sys_allow_interrupts(), sys_stop_interrupts(), pbuf::tot_len, and u8_t. Referenced by arp_arp_input(), dhcp_delete_request(), dhcp_recv(), dhcp_stop(), etharp_arp_input(), etharp_query(), etharp_tmr(), http_recv(), icmp_dest_unreach(), icmp_input(), icmp_time_exceeded(), ip_forward(), ip_frag(), ip_input(), ip_reass(), netbuf_alloc(), netbuf_delete(), netbuf_free(), netbuf_ref(), netconn_delete(), pbuf_dechain(), pbuf_realloc(), pbuf_take(), rt_3c905cif_input(), rt_rtl8139if_input(), tcpip_input(), and update_arp_entry(). { struct pbuf *q; u8_t count; unsigned int state; if (p == NULL) { DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n")); return 0; } // 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_stop_interrupts(&state); /* de-allocate all consecutive pbufs from the head of the chain that * obtain a zero reference count */ while (p != NULL) { /* all pbufs in a chain are referenced at least once */ LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0); p->ref--; /* this pbuf is no longer referenced to? */ if (p->ref == 0) { /* remember next pbuf in chain for next iteration */ q = p->next; /* 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); /* a RAM/ROM referencing pbuf */ } else if (p->flags == PBUF_FLAG_ROM || p->flags == PBUF_FLAG_REF) { memp_freep(MEMP_PBUF, p); /* pbuf with data */ } else { mem_free(p); } count++; /* proceed to next pbuf */ p = q; /* p->ref > 0, this pbuf is still referenced to */ /* (so the remaining pbufs in chain as well) */ } else { /* stop walking through chain */ p = NULL; } } sys_allow_interrupts(&state); pbuf_refresh(); // PERF_STOP("pbuf_free"); /* return number of de-allocated pbufs */ return count; }

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u8_t pbuf_header (  struct pbuf *  p, s16_t  header_size )

Adjusts the payload pointer to hide or reveal headers in the payload. Adjusts the ->payload pointer so that space for a header (dis)appears in the pbuf payload. The ->payload, ->tot_len and ->len fields are adjusted. Parameters: hdr_size  Number of bytes to increment header size which increases the size of the pbuf. New space is on the front. (Using a negative value decreases the header size.) PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer. Returns: 1 on failure, 0 on success. Definition at line 520 of file pbuf.c. References DEBUGF, pbuf::flags, pbuf::len, pbuf::payload, PBUF_DEBUG, PBUF_FLAG_POOL, PBUF_FLAG_RAM, PBUF_FLAG_REF, PBUF_FLAG_ROM, s16_t, pbuf::tot_len, and u8_t. Referenced by etharp_output(), icmp_input(), ip_input(), ip_output_if(), rt_3c905cif_input(), and rt_rtl8139if_input(). { void *payload; /* remember current payload pointer */ payload = p->payload; /* pbuf types containing payloads? */ if (p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_POOL) { /* set new payload pointer */ p->payload = (u8_t *)p->payload - header_size; /* boundary check fails? */ if ((u8_t *)p->payload < (u8_t *)p + sizeof(struct pbuf)) { DEBUGF( PBUF_DEBUG | 2, ("pbuf_header: failed as %p < %p\n", (u8_t *)p->payload, (u8_t *)p + sizeof(struct pbuf)) );\ /* restore old payload pointer */ p->payload = payload; /* bail out unsuccesfully */ return 1; } /* pbuf types refering to payloads? */ } else if (p->flags == PBUF_FLAG_REF || p->flags == PBUF_FLAG_ROM) { /* hide a header in the payload? */ if ((header_size < 0) && (header_size - p->len <= 0)) { /* increase payload pointer */ p->payload = (u8_t *)p->payload - header_size; } else { /* cannot expand payload to front (yet!) * bail out unsuccesfully */ return 1; } } DEBUGF( PBUF_DEBUG, ("pbuf_header: old %p new %p (%d)\n", payload, p->payload, header_size) ); /* modify pbuf length fields */ p->len += header_size; p->tot_len += header_size; return 0; }

void pbuf_init (  void   )

Initializes the pbuf module. A large part of memory is allocated for holding the pool of pbufs. The size of the individual pbufs in the pool is given by the size parameter, and the number of pbufs in the pool by the num parameter. After the memory has been allocated, the pbufs are set up. The ->next pointer in each pbuf is set up to point to the next pbuf in the pool. Definition at line 86 of file pbuf.c. References pbuf::len, LWIP_ASSERT, MEM_ALIGN, pbuf::next, NULL, pbuf_pool, pbuf_pool_alloc_lock, pbuf_pool_free_lock, pbuf_pool_free_sem, pbuf_pool_memory, sys_sem_new(), u16_t, and u8_t. { struct pbuf *p, *q = NULL; u16_t i; pbuf_pool = (struct pbuf *)&pbuf_pool_memory[0]; LWIP_ASSERT("pbuf_init: pool aligned", (long)pbuf_pool % MEM_ALIGNMENT == 0); #ifdef PBUF_STATS lwip_stats.pbuf.avail = PBUF_POOL_SIZE; #endif /* PBUF_STATS */ /* Set up ->next pointers to link the pbufs of the pool together */ p = pbuf_pool; for(i = 0; i < PBUF_POOL_SIZE; ++i) { p->next = (struct pbuf *)((u8_t *)p + PBUF_POOL_BUFSIZE + sizeof(struct pbuf)); p->len = p->tot_len = PBUF_POOL_BUFSIZE; p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf))); q = p; p = p->next; } /* The ->next pointer of last pbuf is NULL to indicate that there are no more pbufs in the pool */ q->next = NULL; #if !SYS_LIGHTWEIGHT_PROT pbuf_pool_alloc_lock = 0; pbuf_pool_free_lock = 0; pbuf_pool_free_sem = sys_sem_new(1); #endif }

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void pbuf_realloc (  struct pbuf *  p, u16_t  new_len )

Shrink a pbuf chain to a desired length. Parameters: p  pbuf to shrink. new_len  desired new length of pbuf chain Depending on the desired length, the first few pbufs in a chain might be skipped and left unchanged. The new last pbuf in the chain will be resized, and any remaining pbufs will be freed. Note: If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted. Bug: Cannot grow the size of a pbuf (chain) (yet). Definition at line 445 of file pbuf.c. References pbuf::flags, pbuf::len, LWIP_ASSERT, mem_realloc(), NULL, PBUF_FLAG_POOL, PBUF_FLAG_RAM, PBUF_FLAG_REF, PBUF_FLAG_ROM, pbuf_free(), pbuf_refresh(), s16_t, pbuf::tot_len, u16_t, and u8_t. Referenced by dhcp_discover(), dhcp_inform(), dhcp_rebind(), dhcp_release(), dhcp_renew(), dhcp_select(), ip_frag(), ip_input(), and slipif_input(). { struct pbuf *q; u16_t rem_len; /* remaining length */ s16_t grow; LWIP_ASSERT("pbuf_realloc: sane p->flags", p->flags == PBUF_FLAG_POOL || p->flags == PBUF_FLAG_ROM || p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_REF); /* desired length larger than current length? */ if (new_len >= p->tot_len) { /* enlarging not yet supported */ return; } /* the pbuf chain grows by (new_len - p->tot_len) bytes * (which may be negative in case of shrinking) */ grow = new_len - p->tot_len; /* first, step over any pbufs that should remain in the chain */ rem_len = new_len; q = p; /* this pbuf should be kept? */ while (rem_len > q->len) { /* decrease remaining length by pbuf length */ rem_len -= q->len; /* decrease total length indicator */ q->tot_len += grow; /* proceed to next pbuf in chain */ q = q->next; } /* we have now reached the new last pbuf (in q) */ /* rem_len == desired length for pbuf q */ /* shrink allocated memory for PBUF_RAM */ /* (other types merely adjust their length fields */ if ((q->flags == PBUF_FLAG_RAM) && (rem_len != q->len)) { /* reallocate and adjust the length of the pbuf that will be split */ mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len); } /* adjust length fields for new last pbuf */ q->len = rem_len; q->tot_len = q->len; /* any remaining pbufs in chain? */ if (q->next != NULL) { /* free remaining pbufs in chain */ pbuf_free(q->next); } /* q is last packet in chain */ q->next = NULL; pbuf_refresh(); }

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void pbuf_ref (  struct pbuf *  p  )

Increment the reference count of the pbuf. Parameters: p  pbuf to increase reference counter of Definition at line 677 of file pbuf.c. References NULL, pbuf::ref, sys_allow_interrupts(), and sys_stop_interrupts(). Referenced by etharp_query(), and pbuf_chain(). { unsigned int state; /* pbuf given? */ if (p != NULL) { sys_stop_interrupts(&state); ++(p->ref); sys_allow_interrupts(&state); } }

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void pbuf_ref_chain (  struct pbuf *  p  )

Increment the reference count of all pbufs in a chain. Parameters: p  first pbuf of chain Definition at line 696 of file pbuf.c. References pbuf::next, NULL, pbuf::ref, sys_allow_interrupts(), and sys_stop_interrupts(). { unsigned int state; sys_stop_interrupts(&state); while (p != NULL) { ++p->ref; p = p->next; } sys_allow_interrupts(&state); }

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struct pbuf* pbuf_take (  struct pbuf *  p  )

Create PBUF_POOL (or PBUF_RAM) copies of PBUF_REF pbufs. Go through a pbuf chain and replace any PBUF_REF buffers with PBUF_POOL (or PBUF_RAM) pbufs, each taking a copy of the referenced data. Note: You MUST explicitly use p = pbuf_take(p); The pbuf you give as argument, may have been replaced by pbuf_take()! Any replaced pbufs will be freed through pbuf_free(). Used to queue packets on behalf of the lwIP stack, such as ARP based queueing. Parameters: p  Head of pbuf chain to process Returns: Pointer to new head of pbuf chain Definition at line 797 of file pbuf.c. References DBG_TRACE, DEBUGF, LWIP_ASSERT, NULL, pbuf_alloc(), PBUF_DEBUG, PBUF_FLAG_REF, pbuf_free(), PBUF_POOL, PBUF_RAM, and PBUF_RAW. Referenced by etharp_query(). { struct pbuf *q , *prev, *head; LWIP_ASSERT("pbuf_take: p != NULL\n", p != NULL); DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_take(%p)\n", (void*)p)); prev = NULL; head = p; /* iterate through pbuf chain */ do { /* pbuf is of type PBUF_REF? */ if (p->flags == PBUF_FLAG_REF) { DEBUGF(PBUF_DEBUG | DBG_TRACE, ("pbuf_take: encountered PBUF_REF %p\n", (void *)p)); /* allocate a pbuf (w/ payload) fully in RAM */ /* PBUF_POOL buffers are faster if we can use them */ if (p->len <= PBUF_POOL_BUFSIZE) { q = pbuf_alloc(PBUF_RAW, p->len, PBUF_POOL); if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_POOL\n")); } else { /* no replacement pbuf yet */ q = NULL; DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: PBUF_POOL too small to replace PBUF_REF\n")); } /* no (large enough) PBUF_POOL was available? retry with PBUF_RAM */ if (q == NULL) { q = pbuf_alloc(PBUF_RAW, p->len, PBUF_RAM); if (q == NULL) DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_RAM\n")); } /* replacement pbuf could be allocated? */ if (q != NULL) { /* copy p to q */ /* copy successor */ q->next = p->next; /* remove linkage from original pbuf */ p->next = NULL; /* remove linkage to original pbuf */ if (prev != NULL) { /* prev->next == p at this point */ LWIP_ASSERT("prev->next == p", prev->next == p); /* break chain and insert new pbuf instead */ prev->next = q; /* prev == NULL, so we replaced the head pbuf of the chain */ } else { head = q; } /* copy pbuf payload */ memcpy(q->payload, p->payload, p->len); q->tot_len = p->tot_len; q->len = p->len; /* in case p was the first pbuf, it is no longer refered to by * our caller, as the caller MUST do p = pbuf_take(p); * in case p was not the first pbuf, it is no longer refered to * by prev. we can safely free the pbuf here. * (note that we have set p->next to NULL already so that * we will not free the rest of the chain by accident.) */ pbuf_free(p); /* do not copy ref, since someone else might be using the old buffer */ DEBUGF(PBUF_DEBUG, ("pbuf_take: replaced PBUF_REF %p with %p\n", (void *)p, (void *)q)); p = q; } else { /* deallocate chain */ pbuf_free(head); DEBUGF(PBUF_DEBUG | 2, ("pbuf_take: failed to allocate replacement pbuf for %p\n", (void *)p)); return NULL; } /* p->flags != PBUF_FLAG_REF */ } else { DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: skipping pbuf not of type PBUF_REF\n")); } /* remember this pbuf */ prev = p; /* proceed to next pbuf in original chain */ p = p->next; } while (p); DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: end of chain reached.\n")); return head; }

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