vjcomp.h

用于嵌入式系统的TCP/IP协议栈及若干服务

/*
*            Copyright (c) 1998-2001 by NETsilicon Inc.
*
*  This software is copyrighted by and is the sole property of
*  NETsilicon.  All rights, title, ownership, or other interests
*  in the software remain the property of NETsilicon.  This
*  software may only be used in accordance with the corresponding
*  license agreement.  Any unauthorized use, duplication, transmission,
*  distribution, or disclosure of this software is expressly forbidden.
*
*  This Copyright notice may not be removed or modified without prior
*  written consent of NETsilicon.
*
*  NETsilicon, reserves the right to modify this software
*  without notice.
*
*  NETsilicon
*  411 Waverley Oaks Road                  USA 781.647.1234
*  Suite 227                               http://www.netsilicon.com
*  Waltham, MA 02452                       [e-mail]
*
*************************************************************************
*  $Date: 2001/09/20 10:25:00 $
*  $Source: M:/psisrc/ppp/incl/rcs/vjcomp.h $
*  $Revision: 1.15 $
*************************************************************************
*  File Description:  Header file for routines that call VJ compression  
*                                                                        
*************************************************************************/

#ifndef _VJCOMP_
#define _VJCOMP_

/* defines to handle special items */
#define u_short u16
#define u_char  u8
#define u_int   u32
#define u_long  u32

#include "vjcdefs.h"

#include "ip.h"

struct mbuf {
       u8  *m_off; /* pointer to start of data */
       long     m_len;  /* length of data */
};

#define mtod(m, t) ((t)(m->m_off))

/*
 * Bits in first octet of compressed packet
 */

/* flag bits for what changed in a packet */

#define NEW_C  0x40
#define NEW_I  0x20
#define TCP_PUSH_BIT 0x10

#define NEW_S  0x08
#define NEW_A  0x04
#define NEW_W  0x02
#define NEW_U  0x01

/* reserved, special-case values of above */
#define SPECIAL_I (NEW_S|NEW_W|NEW_U)        /* echoed interactive traffic */
#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U)  /* unidirectional data */
#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)


/*
 * "state" data for each active tcp conversation on the wire.  This is
 * basically a copy of the entire IP/TCP header from the last packet together
 * with a small identifier the transmit & receive ends of the line use to
 * locate saved header.
 */
struct cstate {
    struct cstate *cs_next;  /* next most recently used cstate (xmit only) */
    u16    cs_hlen;         /* size of hdr (receive only) */
    u8     cs_id;            /* connection # associated with this state */
    u8     cs_filler;
    union {
         char   hdr[MAX_HDR];
         IPH_T  csu_ip[SIZEOF_IPH_T];   /* ip/tcp hdr from most recent packet */
    } slcs_u;
};

#define cs_ip slcs_u.csu_ip
#define cs_hdr slcs_u.csu_hdr

/*
 * all the state data for one serial line (we need one of these per line).
 */
typedef struct slcompress {
    struct cstate *last_cs;            /* most recently used tstate */
    u8     last_recv;                  /* last rcvd conn. id */
    u8     last_xmit;                  /* last sent conn. id */
    u16    flags;
    struct cstate tstate[MAX_STATES];  /* xmit connection states */
    struct cstate rstate[MAX_STATES];  /* receive connection states */
} slcompress;



/* #define OVBCOPY(a, b, c) memmove(b, a, c) */

/* flag values */
#define SLF_TOSS 1       /* tossing rcvd frames because of input err */

/*
 * The following macros are used to encode and decode numbers.  They all
 * assume that `cp' points to a buffer where the next byte encoded (decoded)
 * is to be stored (retrieved).  Since the decode routines do arithmetic,
 * they have to convert from and to network byte order.
 */

/*
 * ENCODE encodes a number that is known to be non-zero.  ENCODEZ checks for
 * zero (zero has to be encoded in the long, 3 byte form).
 */
#define ENCODE(n) { \
    if ((u16)(n) >= 256) { \
         *cp++ = 0; \
		 *cp++ = (u_char)((n) >> 8); \
         *cp++ = (u_char)(n); \
    } else { \
         *cp++ = (u_char)(n); \
    } \
}
#define ENCODEZ(n) { \
    if ((u16)(n) >= 256 || (u_short)(n) == 0) { \
         *cp++ = 0; \
         *cp++ = (u_char)((n) >> 8); \
         *cp++ = (u_char)(n); \
    } else { \
         *cp++ = (u_char)(n); \
    } \
}

/*
 * DECODEL takes the (compressed) change at byte cp and adds it to the
 * current value of packet field 'f' (which must be a 4-byte (long) integer
 * in network byte order).  DECODES does the same for a 2-byte (short) field.
 * DECODEU takes the change at cp and stuffs it into the (short) field f.
 * 'cp' is updated to point to the next field in the compressed header.
 */
#define DECODEL(f) { \
    if (*cp == 0) {\
         HostToNet32 ((f), NetToHost32((f)) + (((u32)cp[1] << 8) | (u32)cp[2])); \
         cp += 3; \
    } else { \
         HostToNet32 ((f), NetToHost32((f)) + (u32)*cp++); \
    } \
}
#define DECODES(f) { \
    if (*cp == 0) {\
         HostToNet16 ((f), (u16)(NetToHost16((f)) + (u16)(((u16)cp[1] << 8) | (u16)cp[2]))); \
         cp += 3; \
    } else { \
         HostToNet16 ((f), (u16)(NetToHost16((f)) + (u16)*cp++)); \
    } \
}
#define DECODEU(f) { \
    if (*cp == (u8)0) {\
         HostToNet16 ((f), (u16)((u16)(cp[1] << 8) | (u16)cp[2])); \
         cp += (u8)3; \
    } else { \
         HostToNet16 ((f), (u16)*cp++); \
    } \
}

extern  int      is_tcpip(char *bufp);
extern  char     *fns_compress(char *bufp, u16 *len, u8 *mtype, u8 comp_cid, slcompress *slcomp);
extern  char     *fns_uncompress(u8 *bufp, u16 len, int mtype, slcompress * slcomp);
extern  void     sl_compress_init(slcompress *comp);

#endif /* _VJCOMP_ */