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vj.c in Mylwip.rar

			
/*
 * Routines to compress and uncompess tcp packets (for transmission
 * over low speed serial lines.
 *
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
 *	- Initial distribution.
 *
 * Modified June 1993 by Paul Mackerras, paulus@cs.anu.edu.au,
 * so that the entire packet being decompressed doesn't have
 * to be in contiguous memory (just the compressed header).
 *
 * Modified March 1998 by Guy Lancaster, glanca@gesn.com,
 * for a 16 bit processor.
 */

#include "ppp.h"
#include "vj.h"
#include "pppdebug.h"


#if VJ_SUPPORT > 0

#if LINK_STATS
#define INCR(counter) ++comp->stats.counter
#else
#define INCR(counter)
#endif

#if defined(NO_CHAR_BITFIELDS)
#define getip_hl(base)	((base).ip_hl_v&0xf)
#define getth_off(base)	(((base).th_x2_off&0xf0)>>4)
#else
#define getip_hl(base)	((base).ip_hl)
#define getth_off(base)	((base).th_off)
#endif

void vj_compress_init(struct vjcompress *comp)
{
	register u_int i;
	register struct cstate *tstate = comp->tstate;
	
#if MAX_SLOTS == 0
	memset((char *)comp, 0, sizeof(*comp));
#endif
	comp->maxSlotIndex = MAX_SLOTS - 1;
	comp->compressSlot = 0;		/* Disable slot ID compression by default. */
	for (i = MAX_SLOTS - 1; i > 0; --i) {
		tstate[i].cs_id = i;
		tstate[i].cs_			

			...
			...
			... to be continued.

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