netbuf.h

在ARM7和UC/OSII的平台上实现了GPS自动报站的功能,涉及GPS模块LEA_4S的驱动,位置速寻算法,语音芯片ISD4004的录放音驱动,LED页面管理等等.从启动代码到操作系统的移植以及到业

/*
 * FILENAME: netbuf.h
 *
 * Copyright 1998- 2000 By InterNiche Technologies Inc. All rights reserved
 *
 * Descriptions of the packet buffer structure, etc. 
 *
 * MODULE: INET
 *
 *
 * PORTABLE: yes
 */

/* Additional Copyrights: */
/* Portions Copyright 1990-1993 by NetPort Software. 
 * Portions Copyright 1986 by Carnegie Mellon 
 * Portions Copyright 1983 by the Massachusetts Institute of 
 * Technology
 */
 
/* Each buffer is in a 
 * queue, either the free queue or the used queue (or the buffer is 
 * currently being used by a user program or the interrupt level 
 * routines, in which case it does not appear in a queue). When a 
 * buffer is in a queue, it has a pointer to the next buffer in the 
 * queue. If there is no next buffer, its pointer points at null. 
 * Also, each buffer knows its own length. 
 */

#ifndef _NETBUF_H
#define  _NETBUF_H   1

/* This include file gives the structure of PACKET buffers. 
 * INCOMING: Incoming packets are always front-aligned in the 
 * nb_buff field. The nb_prot pointer is set to nb_buff by the 
 * receiver and advanced by each layer of the stack before 
 * upcalling the next; ie the ethernet driver bumps the prot field 
 * by 14 and decrements plen by 14. PACKETs are pk_alloc()ed by 
 * the receiving net layer and pk_free()ed by the transport layer 
 * or application when it's finished with them. OUTGOING: 
 * Protocols install data into nb_buff with a front pad big enough 
 * to accomadate the biggest likely protocol headers, ususally 
 * about 62 bytes (14 ether + 24 IP + 24 TCP, where IP & TCP each 
 * have option fields.) prot plen are set for this data, and the 
 * protocol headers are prepended as the packet goes down the 
 * stack. nb_buff is not used in this case except for overflow 
 * checks. PACKETs are pk_alloc()ed by the sending protocol and 
 * freed by the lower layer level that dispatches them, usually 
 * net link layer driver. They can be held by ARP for several 
 * seconds while awaiting arp replys on initial sends to a new IP 
 * host, and the ARP code will free them when a reply comes in or 
 * times out. 
 */

struct netbuf
{
   struct netbuf * next;   /* queue link */
   char   * nb_buff;    /* beginning of raw buffer */
   unsigned nb_blen;    /* length of raw buffer */
   char   * nb_prot;    /* beginning of protocol data */
   unsigned nb_plen;    /* length of protocol data */
   long     nb_tstamp;  /* packet timestamp */
   struct net *   net;  /* the interface (net) it came in on, 0-n */
   ip_addr  fhost;      /* IP address asociated with packet */
   unsigned short type; /* IP==0800 filled in by recever(rx) or net layer.(tx) */
   unsigned inuse;      /* use count, for cloning buffer */

#ifdef PPP_MULTILINK
   void * link;         /* which of Multiple links to use */
#endif /* PPP_MULTILINK */
   
#ifdef MINI_TCP            /* Mini TCP has no mbuf wrappers, so: */
   char *   m_data;        /* pointer to TCP data in nb_buff */
   unsigned m_len;         /* length of m_data */
   struct netbuf * m_next; /* sockbuf que link */
#endif   /* MINI_TCP */

#ifdef IP_MULTICAST
   struct ip_moptions * imo;  /* IP multicast options */
#endif

};

typedef struct netbuf * PACKET;     /* struct netbuf in netbuf.h */

/* count & sizes for the fre buffer queues */
extern   unsigned lilbufs;    /* number of small bufs to init */
extern   unsigned lilbufsiz;  /* big enough for average packet */
extern   unsigned bigbufs;    /* number of big bufs to init */
extern   unsigned bigbufsiz;  /* big enough for max. ethernet packet */

/* Pack buffer routines, Defined in the new system for each port: */
PACKET   pk_alloc(unsigned size);      /* allocate a packet for sending */
void     pk_free(PACKET);
int      pk_init(void);    /* call at init time to set up for pk_allocs */

#endif   /*  _NETBUF_H */