/* * Copyright (c) 2001-2004 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 "lwip/opt.h"#include "lwip/err.h"#ifdef __cplusplusextern "C" {#endif#define PBUF_TRANSPORT_HLEN 20#define PBUF_IP_HLEN        20typedef enum {  PBUF_TRANSPORT,  PBUF_IP,  PBUF_LINK,  PBUF_RAW} pbuf_layer;typedef enum {  PBUF_RAM, /* pbuf data is stored in RAM */  PBUF_ROM, /* pbuf data is stored in ROM */  PBUF_REF, /* pbuf comes from the pbuf pool */  PBUF_POOL /* pbuf payload refers to RAM */} pbuf_type;/** indicates this packet's data should be immediately passed to the application */#define PBUF_FLAG_PUSH 0x01Ustruct 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;    /** pbuf_type as u8_t instead of enum to save space */  u8_t /*pbuf_type*/ type;  /** misc flags */  u8_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;  };/* Initializes the pbuf module. This call is empty for now, but may not be in future. */#define pbuf_init()struct pbuf *pbuf_alloc(pbuf_layer l, u16_t size, pbuf_type type);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_cat(struct pbuf *head, struct pbuf *tail);void pbuf_chain(struct pbuf *head, struct pbuf *tail);struct pbuf *pbuf_dechain(struct pbuf *p);err_t pbuf_copy(struct pbuf *p_to, struct pbuf *p_from);u16_t pbuf_copy_partial(struct pbuf *p, void *dataptr, u16_t len, u16_t offset);#ifdef __cplusplus}#endif#endif /* __LWIP_PBUF_H__ */