1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
6  *                    Carsten Bormann <cabo@cs.tu-berlin.de>
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
53  * It builds a sliding hash sum of the previous 3-and-a-bit characters
58 #define HASH(state, x) state->hash = (state->hash << 4) ^ (x)
77       if (state->dict[state->hash] == *source) {  in compress()
78 	flags |= bitmask;	/* Guess was right - don't output */  in compress()
80 	state->dict[state->hash] = *source;  in compress()
84       len--;  in compress()
88   return (dest - orgdest);  in compress()
94   while (len--) {  in SyncTable()
95     *dest++ = state->dict[state->hash] = *source;  in SyncTable()
109     len--;  in decompress()
112 	*dest = state->dict[state->hash];	/* Guess correct */  in decompress()
115 	  break;		/* we seem to be really done -- cabo */  in decompress()
116 	state->dict[state->hash] = *source;	/* Guess wrong */  in decompress()
118 	len--;  in decompress()
123   return (dest - orgdest);  in decompress()
137   state->hash = 0;  in Pred1ResetInput()
138   memset(state->dict, '\0', sizeof state->dict);  in Pred1ResetInput()
146   state->hash = 0;  in Pred1ResetOutput()
147   memset(state->dict, '\0', sizeof state->dict);  in Pred1ResetOutput()
179   u_char *cp, *wp, *hp;  in Pred1Output()  local
186   hp = wp = MBUF_CTOP(mwp);  in Pred1Output()
188   *wp++ = *cp++ = orglen >> 8;  in Pred1Output()
189   *wp++ = *cp++ = orglen & 0377;  in Pred1Output()
192   mbuf_Read(bp, cp, orglen - 2);  in Pred1Output()
196   len = compress(state, bufp + 2, wp, orglen);  in Pred1Output()
197   log_Printf(LogDEBUG, "Pred1Output: orglen (%d) --> len (%d)\n", orglen, len);  in Pred1Output()
198   ccp->uncompout += orglen;  in Pred1Output()
201     wp += len;  in Pred1Output()
202     ccp->compout += len;  in Pred1Output()
204     memcpy(wp, bufp + 2, orglen);  in Pred1Output()
205     wp += orglen;  in Pred1Output()
206     ccp->compout += orglen;  in Pred1Output()
209   *wp++ = fcs & 0377;  in Pred1Output()
210   *wp++ = fcs >> 8;  in Pred1Output()
211   mwp->m_len = wp - MBUF_CTOP(mwp);  in Pred1Output()
222   struct mbuf *wp;  in Pred1Input()  local
226   wp = m_get(MAX_MRU + 2, MB_CCPIN);  in Pred1Input()
229   pp = bufp = MBUF_CTOP(wp);  in Pred1Input()
234   ccp->uncompin += len & 0x7fff;  in Pred1Input()
236     len1 = decompress(state, cp, pp, olen - 4);  in Pred1Input()
237     ccp->compin += olen;  in Pred1Input()
241       fsm_Reopen(&ccp->fsm);  in Pred1Input()
243       m_freem(wp);  in Pred1Input()
246     cp += olen - 4;  in Pred1Input()
250     fsm_Reopen(&ccp->fsm);  in Pred1Input()
251     m_freem(wp);  in Pred1Input()
255     ccp->compin += len;  in Pred1Input()
262   fcs = hdlc_Fcs(bufp, wp->m_len = pp - bufp);  in Pred1Input()
264     wp->m_offset += 2;		/* skip length */  in Pred1Input()
265     wp->m_len -= 4;		/* skip length & CRC */  in Pred1Input()
266     pp = MBUF_CTOP(wp);  in Pred1Input()
269       wp->m_offset++;  in Pred1Input()
270       wp->m_len--;  in Pred1Input()
272       wp->m_offset += 2;  in Pred1Input()
273       wp->m_len -= 2;  in Pred1Input()
277     return wp;  in Pred1Input()
282     log_Printf(LogCCP, "%s: Bad %scompressed CRC-16\n",  in Pred1Input()
283                ccp->fsm.link->name, pre);  in Pred1Input()
284     fsm_Reopen(&ccp->fsm);  in Pred1Input()
285     m_freem(wp);  in Pred1Input()
308   o->hdr.len = 2;  in Pred1InitOptsOutput()
315   if (o->hdr.len != 2) {  in Pred1SetOpts()
316     o->hdr.len = 2;  in Pred1SetOpts()