src/include/lwip/pbuf.h

/*
 * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 * 
 * Author: Adam Dunkels <adam@sics.se>
 *
 */
/*-----------------------------------------------------------------------------------*/
#ifndef __LWIP_PBUF_H__
#define __LWIP_PBUF_H__

#include "arch/cc.h"


#define PBUF_TRANSPORT_HLEN 20
#define PBUF_IP_HLEN        20

typedef enum {
  PBUF_TRANSPORT,
  PBUF_IP,
  PBUF_LINK,
  PBUF_RAW
} pbuf_layer;

typedef enum {
  PBUF_RAM,
  PBUF_ROM,
  PBUF_REF,
  PBUF_POOL
} pbuf_flag;

/* Definitions for the pbuf flag field (these are not the flags that
   are passed to pbuf_alloc()). */
#define PBUF_FLAG_RAM   0x00U    /* Flags that pbuf data is stored in RAM */
#define PBUF_FLAG_ROM   0x01U    /* Flags that pbuf data is stored in ROM */
#define PBUF_FLAG_POOL  0x02U    /* Flags that the pbuf comes from the pbuf pool */
#define PBUF_FLAG_REF   0x04U    /* Flags thet the pbuf payload refers to RAM */

/** indicates this packet was broadcast on the link */
#define PBUF_FLAG_LINK_BROADCAST 0x80U

struct pbuf {
  /** next pbuf in singly linked pbuf chain */
  struct pbuf *next;

  /** pointer to the actual data in the buffer */
  void *payload;
  
  /**
   * total length of this buffer and all next buffers in chain
   * belonging to the same packet.
   *
   * For non-queue packet chains this is the invariant:
   * p->tot_len == p->len + (p->next? p->next->tot_len: 0)
   */
  u16_t tot_len;
  
  /* length of this buffer */
  u16_t len;  

  /* flags telling the type of pbuf */
  u16_t flags;
  
  /**
   * the reference count always equals the number of pointers
   * that refer to this pbuf. This can be pointers from an application,
   * the stack itself, or pbuf->next pointers from a chain.
   */
  u16_t ref;
  
};

/* pbuf_init():

   Initializes the pbuf module. The num parameter determines how many
   pbufs that should be allocated to the pbuf pool, and the size
   parameter specifies the size of the data allocated to those.  */
void pbuf_init(void);

struct 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);
struct pbuf *pbuf_take(struct pbuf *f);
struct pbuf *pbuf_dechain(struct pbuf *p);

#endif /* __LWIP_PBUF_H__ */