333 lines
8.3 KiB
C
333 lines
8.3 KiB
C
/*-
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* Copyright (c) 1997 Brian Somers <brian@Awfulhak.org>
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* Ian Donaldson <iand@labtam.labtam.oz.au>
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* Carsten Bormann <cabo@cs.tu-berlin.de>
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* Dave Rand <dlr@bungi.com>/<dave_rand@novell.com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: pred.c,v 1.20.2.12 1998/05/01 19:25:40 brian Exp $
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*/
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#include <sys/types.h>
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#include <stdlib.h>
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#include <string.h>
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#include "mbuf.h"
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#include "log.h"
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#include "timer.h"
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#include "fsm.h"
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#include "lqr.h"
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#include "hdlc.h"
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#include "lcp.h"
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#include "ccp.h"
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#include "pred.h"
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/* The following hash code is the heart of the algorithm:
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* It builds a sliding hash sum of the previous 3-and-a-bit characters
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* which will be used to index the guess table.
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* A better hash function would result in additional compression,
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* at the expense of time.
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*/
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#define HASH(state, x) state->hash = (state->hash << 4) ^ (x)
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#define GUESS_TABLE_SIZE 65536
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struct pred1_state {
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u_short hash;
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u_char dict[GUESS_TABLE_SIZE];
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};
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static int
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compress(struct pred1_state *state, u_char *source, u_char *dest, int len)
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{
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int i, bitmask;
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unsigned char *flagdest, flags, *orgdest;
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orgdest = dest;
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while (len) {
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flagdest = dest++;
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flags = 0; /* All guess wrong initially */
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for (bitmask = 1, i = 0; i < 8 && len; i++, bitmask <<= 1) {
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if (state->dict[state->hash] == *source) {
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flags |= bitmask; /* Guess was right - don't output */
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} else {
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state->dict[state->hash] = *source;
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*dest++ = *source; /* Guess wrong, output char */
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}
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HASH(state, *source++);
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len--;
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}
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*flagdest = flags;
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}
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return (dest - orgdest);
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}
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static void
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SyncTable(struct pred1_state *state, u_char * source, u_char * dest, int len)
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{
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while (len--) {
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if (state->dict[state->hash] != *source)
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state->dict[state->hash] = *source;
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HASH(state, *dest++ = *source++);
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}
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}
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static int
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decompress(struct pred1_state *state, u_char * source, u_char * dest, int len)
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{
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int i, bitmask;
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unsigned char flags, *orgdest;
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orgdest = dest;
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while (len) {
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flags = *source++;
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len--;
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for (i = 0, bitmask = 1; i < 8; i++, bitmask <<= 1) {
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if (flags & bitmask) {
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*dest = state->dict[state->hash]; /* Guess correct */
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} else {
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if (!len)
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break; /* we seem to be really done -- cabo */
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state->dict[state->hash] = *source; /* Guess wrong */
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*dest = *source++; /* Read from source */
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len--;
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}
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HASH(state, *dest++);
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}
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}
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return (dest - orgdest);
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}
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static void
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Pred1Term(void *v)
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{
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struct pred1_state *state = (struct pred1_state *)v;
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free(state);
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}
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static void
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Pred1ResetInput(void *v)
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{
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struct pred1_state *state = (struct pred1_state *)v;
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state->hash = 0;
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memset(state->dict, '\0', sizeof state->dict);
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log_Printf(LogCCP, "Predictor1: Input channel reset\n");
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}
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static void
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Pred1ResetOutput(void *v)
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{
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struct pred1_state *state = (struct pred1_state *)v;
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state->hash = 0;
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memset(state->dict, '\0', sizeof state->dict);
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log_Printf(LogCCP, "Predictor1: Output channel reset\n");
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}
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static void *
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Pred1InitInput(struct lcp_opt *o)
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{
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struct pred1_state *state;
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state = (struct pred1_state *)malloc(sizeof(struct pred1_state));
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if (state != NULL)
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Pred1ResetInput(state);
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return state;
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}
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static void *
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Pred1InitOutput(struct lcp_opt *o)
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{
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struct pred1_state *state;
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state = (struct pred1_state *)malloc(sizeof(struct pred1_state));
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if (state != NULL)
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Pred1ResetOutput(state);
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return state;
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}
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static int
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Pred1Output(void *v, struct ccp *ccp, struct link *l, int pri, u_short proto,
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struct mbuf *bp)
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{
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struct pred1_state *state = (struct pred1_state *)v;
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struct mbuf *mwp;
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u_char *cp, *wp, *hp;
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int orglen, len;
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u_char bufp[MAX_MTU + 2];
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u_short fcs;
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orglen = mbuf_Length(bp) + 2; /* add count of proto */
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mwp = mbuf_Alloc((orglen + 2) / 8 * 9 + 12, MB_HDLCOUT);
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hp = wp = MBUF_CTOP(mwp);
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cp = bufp;
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*wp++ = *cp++ = orglen >> 8;
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*wp++ = *cp++ = orglen & 0377;
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*cp++ = proto >> 8;
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*cp++ = proto & 0377;
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mbuf_Read(bp, cp, orglen - 2);
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fcs = hdlc_Fcs(INITFCS, bufp, 2 + orglen);
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fcs = ~fcs;
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len = compress(state, bufp + 2, wp, orglen);
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log_Printf(LogDEBUG, "Pred1Output: orglen (%d) --> len (%d)\n", orglen, len);
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ccp->uncompout += orglen;
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if (len < orglen) {
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*hp |= 0x80;
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wp += len;
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ccp->compout += len;
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} else {
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memcpy(wp, bufp + 2, orglen);
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wp += orglen;
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ccp->compout += orglen;
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}
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*wp++ = fcs & 0377;
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*wp++ = fcs >> 8;
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mwp->cnt = wp - MBUF_CTOP(mwp);
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hdlc_Output(l, PRI_NORMAL, ccp_Proto(ccp), mwp);
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return 1;
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}
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static struct mbuf *
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Pred1Input(void *v, struct ccp *ccp, u_short *proto, struct mbuf *bp)
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{
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struct pred1_state *state = (struct pred1_state *)v;
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u_char *cp, *pp;
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int len, olen, len1;
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struct mbuf *wp;
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u_char *bufp;
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u_short fcs;
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wp = mbuf_Alloc(MAX_MTU + 2, MB_IPIN);
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cp = MBUF_CTOP(bp);
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olen = mbuf_Length(bp);
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pp = bufp = MBUF_CTOP(wp);
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*pp++ = *cp & 0177;
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len = *cp++ << 8;
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*pp++ = *cp;
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len += *cp++;
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ccp->uncompin += len & 0x7fff;
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if (len & 0x8000) {
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len1 = decompress(state, cp, pp, olen - 4);
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ccp->compin += olen;
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len &= 0x7fff;
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if (len != len1) { /* Error is detected. Send reset request */
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log_Printf(LogCCP, "Pred1: Length error\n");
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ccp_SendResetReq(&ccp->fsm);
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mbuf_Free(bp);
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mbuf_Free(wp);
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return NULL;
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}
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cp += olen - 4;
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pp += len1;
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} else {
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ccp->compin += len;
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SyncTable(state, cp, pp, len);
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cp += len;
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pp += len;
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}
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*pp++ = *cp++; /* CRC */
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*pp++ = *cp++;
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fcs = hdlc_Fcs(INITFCS, bufp, wp->cnt = pp - bufp);
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if (fcs != GOODFCS)
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log_Printf(LogDEBUG, "Pred1Input: fcs = 0x%04x (%s), len = 0x%x,"
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" olen = 0x%x\n", fcs, (fcs == GOODFCS) ? "good" : "bad",
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len, olen);
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if (fcs == GOODFCS) {
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wp->offset += 2; /* skip length */
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wp->cnt -= 4; /* skip length & CRC */
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pp = MBUF_CTOP(wp);
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*proto = *pp++;
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if (*proto & 1) {
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wp->offset++;
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wp->cnt--;
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} else {
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wp->offset += 2;
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wp->cnt -= 2;
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*proto = (*proto << 8) | *pp++;
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}
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mbuf_Free(bp);
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return wp;
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} else {
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log_DumpBp(LogHDLC, "Bad FCS", wp);
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ccp_SendResetReq(&ccp->fsm);
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mbuf_Free(wp);
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}
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mbuf_Free(bp);
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return NULL;
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}
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static void
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Pred1DictSetup(void *v, struct ccp *ccp, u_short proto, struct mbuf * bp)
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{
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}
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static const char *
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Pred1DispOpts(struct lcp_opt *o)
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{
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return NULL;
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}
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static void
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Pred1InitOptsOutput(struct lcp_opt *o, const struct ccp_config *cfg)
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{
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o->len = 2;
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}
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static int
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Pred1SetOptsOutput(struct lcp_opt *o)
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{
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if (o->len != 2) {
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o->len = 2;
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return MODE_NAK;
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}
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return MODE_ACK;
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}
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static int
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Pred1SetOptsInput(struct lcp_opt *o, const struct ccp_config *cfg)
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{
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return Pred1SetOptsOutput(o);
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}
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const struct ccp_algorithm Pred1Algorithm = {
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TY_PRED1,
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CCP_NEG_PRED1,
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Pred1DispOpts,
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{
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Pred1SetOptsInput,
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Pred1InitInput,
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Pred1Term,
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Pred1ResetInput,
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Pred1Input,
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Pred1DictSetup
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},
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{
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Pred1InitOptsOutput,
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Pred1SetOptsOutput,
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Pred1InitOutput,
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Pred1Term,
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Pred1ResetOutput,
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Pred1Output
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},
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};
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