diff options
Diffstat (limited to 'drivers/isdn/i4l/isdn_bsdcomp.c')
| -rw-r--r-- | drivers/isdn/i4l/isdn_bsdcomp.c | 930 |
1 files changed, 930 insertions, 0 deletions
diff --git a/drivers/isdn/i4l/isdn_bsdcomp.c b/drivers/isdn/i4l/isdn_bsdcomp.c new file mode 100644 index 000000000..7f28b967e --- /dev/null +++ b/drivers/isdn/i4l/isdn_bsdcomp.c @@ -0,0 +1,930 @@ +/* + * BSD compression module + * + * Patched version for ISDN syncPPP written 1997/1998 by Michael Hipp + * The whole module is now SKB based. + * + */ + +/* + * Update: The Berkeley copyright was changed, and the change + * is retroactive to all "true" BSD software (ie everything + * from UCB as opposed to other peoples code that just carried + * the same license). The new copyright doesn't clash with the + * GPL, so the module-only restriction has been removed.. + */ + +/* + * Original copyright notice: + * + * Copyright (c) 1985, 1986 The Regents of the University of California. + * All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * James A. Woods, derived from original work by Spencer Thomas + * and Joseph Orost. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/fcntl.h> +#include <linux/interrupt.h> +#include <linux/ptrace.h> +#include <linux/ioport.h> +#include <linux/in.h> +#include <linux/slab.h> +#include <linux/tty.h> +#include <linux/errno.h> +#include <linux/string.h> /* used in new tty drivers */ +#include <linux/signal.h> /* used in new tty drivers */ +#include <linux/bitops.h> + +#include <asm/byteorder.h> +#include <asm/types.h> + +#include <linux/if.h> + +#include <linux/if_ether.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/inet.h> +#include <linux/ioctl.h> +#include <linux/vmalloc.h> + +#include <linux/ppp_defs.h> + +#include <linux/isdn.h> +#include <linux/isdn_ppp.h> +#include <linux/ip.h> +#include <linux/tcp.h> +#include <linux/if_arp.h> +#include <linux/ppp-comp.h> + +#include "isdn_ppp.h" + +MODULE_DESCRIPTION("ISDN4Linux: BSD Compression for PPP over ISDN"); +MODULE_LICENSE("Dual BSD/GPL"); + +#define BSD_VERSION(x) ((x) >> 5) +#define BSD_NBITS(x) ((x) & 0x1F) + +#define BSD_CURRENT_VERSION 1 + +#define DEBUG 1 + +/* + * A dictionary for doing BSD compress. + */ + +struct bsd_dict { + u32 fcode; + u16 codem1; /* output of hash table -1 */ + u16 cptr; /* map code to hash table entry */ +}; + +struct bsd_db { + int totlen; /* length of this structure */ + unsigned int hsize; /* size of the hash table */ + unsigned char hshift; /* used in hash function */ + unsigned char n_bits; /* current bits/code */ + unsigned char maxbits; /* maximum bits/code */ + unsigned char debug; /* non-zero if debug desired */ + unsigned char unit; /* ppp unit number */ + u16 seqno; /* sequence # of next packet */ + unsigned int mru; /* size of receive (decompress) bufr */ + unsigned int maxmaxcode; /* largest valid code */ + unsigned int max_ent; /* largest code in use */ + unsigned int in_count; /* uncompressed bytes, aged */ + unsigned int bytes_out; /* compressed bytes, aged */ + unsigned int ratio; /* recent compression ratio */ + unsigned int checkpoint; /* when to next check the ratio */ + unsigned int clear_count; /* times dictionary cleared */ + unsigned int incomp_count; /* incompressible packets */ + unsigned int incomp_bytes; /* incompressible bytes */ + unsigned int uncomp_count; /* uncompressed packets */ + unsigned int uncomp_bytes; /* uncompressed bytes */ + unsigned int comp_count; /* compressed packets */ + unsigned int comp_bytes; /* compressed bytes */ + unsigned short *lens; /* array of lengths of codes */ + struct bsd_dict *dict; /* dictionary */ + int xmit; +}; + +#define BSD_OVHD 2 /* BSD compress overhead/packet */ +#define MIN_BSD_BITS 9 +#define BSD_INIT_BITS MIN_BSD_BITS +#define MAX_BSD_BITS 15 + +/* + * the next two codes should not be changed lightly, as they must not + * lie within the contiguous general code space. + */ +#define CLEAR 256 /* table clear output code */ +#define FIRST 257 /* first free entry */ +#define LAST 255 + +#define MAXCODE(b) ((1 << (b)) - 1) +#define BADCODEM1 MAXCODE(MAX_BSD_BITS) + +#define BSD_HASH(prefix, suffix, hshift) ((((unsigned long)(suffix)) << (hshift)) \ + ^ (unsigned long)(prefix)) +#define BSD_KEY(prefix, suffix) ((((unsigned long)(suffix)) << 16) \ + + (unsigned long)(prefix)) + +#define CHECK_GAP 10000 /* Ratio check interval */ + +#define RATIO_SCALE_LOG 8 +#define RATIO_SCALE (1 << RATIO_SCALE_LOG) +#define RATIO_MAX (0x7fffffff >> RATIO_SCALE_LOG) + +/* + * clear the dictionary + */ + +static void bsd_clear(struct bsd_db *db) +{ + db->clear_count++; + db->max_ent = FIRST - 1; + db->n_bits = BSD_INIT_BITS; + db->bytes_out = 0; + db->in_count = 0; + db->incomp_count = 0; + db->ratio = 0; + db->checkpoint = CHECK_GAP; +} + +/* + * If the dictionary is full, then see if it is time to reset it. + * + * Compute the compression ratio using fixed-point arithmetic + * with 8 fractional bits. + * + * Since we have an infinite stream instead of a single file, + * watch only the local compression ratio. + * + * Since both peers must reset the dictionary at the same time even in + * the absence of CLEAR codes (while packets are incompressible), they + * must compute the same ratio. + */ +static int bsd_check(struct bsd_db *db) /* 1=output CLEAR */ +{ + unsigned int new_ratio; + + if (db->in_count >= db->checkpoint) + { + /* age the ratio by limiting the size of the counts */ + if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX) + { + db->in_count -= (db->in_count >> 2); + db->bytes_out -= (db->bytes_out >> 2); + } + + db->checkpoint = db->in_count + CHECK_GAP; + + if (db->max_ent >= db->maxmaxcode) + { + /* Reset the dictionary only if the ratio is worse, + * or if it looks as if it has been poisoned + * by incompressible data. + * + * This does not overflow, because + * db->in_count <= RATIO_MAX. + */ + + new_ratio = db->in_count << RATIO_SCALE_LOG; + if (db->bytes_out != 0) + { + new_ratio /= db->bytes_out; + } + + if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) + { + bsd_clear(db); + return 1; + } + db->ratio = new_ratio; + } + } + return 0; +} + +/* + * Return statistics. + */ + +static void bsd_stats(void *state, struct compstat *stats) +{ + struct bsd_db *db = (struct bsd_db *) state; + + stats->unc_bytes = db->uncomp_bytes; + stats->unc_packets = db->uncomp_count; + stats->comp_bytes = db->comp_bytes; + stats->comp_packets = db->comp_count; + stats->inc_bytes = db->incomp_bytes; + stats->inc_packets = db->incomp_count; + stats->in_count = db->in_count; + stats->bytes_out = db->bytes_out; +} + +/* + * Reset state, as on a CCP ResetReq. + */ +static void bsd_reset(void *state, unsigned char code, unsigned char id, + unsigned char *data, unsigned len, + struct isdn_ppp_resetparams *rsparm) +{ + struct bsd_db *db = (struct bsd_db *) state; + + bsd_clear(db); + db->seqno = 0; + db->clear_count = 0; +} + +/* + * Release the compression structure + */ +static void bsd_free(void *state) +{ + struct bsd_db *db = (struct bsd_db *) state; + + if (db) { + /* + * Release the dictionary + */ + vfree(db->dict); + db->dict = NULL; + + /* + * Release the string buffer + */ + vfree(db->lens); + db->lens = NULL; + + /* + * Finally release the structure itself. + */ + kfree(db); + } +} + + +/* + * Allocate space for a (de) compressor. + */ +static void *bsd_alloc(struct isdn_ppp_comp_data *data) +{ + int bits; + unsigned int hsize, hshift, maxmaxcode; + struct bsd_db *db; + int decomp; + + static unsigned int htab[][2] = { + { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , + { 9001 , 5 } , { 18013 , 6 } , { 35023 , 7 } , { 69001 , 8 } + }; + + if (data->optlen != 1 || data->num != CI_BSD_COMPRESS + || BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) + return NULL; + + bits = BSD_NBITS(data->options[0]); + + if (bits < 9 || bits > 15) + return NULL; + + hsize = htab[bits - 9][0]; + hshift = htab[bits - 9][1]; + + /* + * Allocate the main control structure for this instance. + */ + maxmaxcode = MAXCODE(bits); + db = kzalloc(sizeof(struct bsd_db), GFP_KERNEL); + if (!db) + return NULL; + + db->xmit = data->flags & IPPP_COMP_FLAG_XMIT; + decomp = db->xmit ? 0 : 1; + + /* + * Allocate space for the dictionary. This may be more than one page in + * length. + */ + db->dict = vmalloc(array_size(hsize, sizeof(struct bsd_dict))); + if (!db->dict) { + bsd_free(db); + return NULL; + } + + /* + * If this is the compression buffer then there is no length data. + * For decompression, the length information is needed as well. + */ + if (!decomp) + db->lens = NULL; + else { + db->lens = vmalloc(array_size(sizeof(db->lens[0]), + maxmaxcode + 1)); + if (!db->lens) { + bsd_free(db); + return (NULL); + } + } + + /* + * Initialize the data information for the compression code + */ + db->totlen = sizeof(struct bsd_db) + (sizeof(struct bsd_dict) * hsize); + db->hsize = hsize; + db->hshift = hshift; + db->maxmaxcode = maxmaxcode; + db->maxbits = bits; + + return (void *)db; +} + +/* + * Initialize the database. + */ +static int bsd_init(void *state, struct isdn_ppp_comp_data *data, int unit, int debug) +{ + struct bsd_db *db = state; + int indx; + int decomp; + + if (!state || !data) { + printk(KERN_ERR "isdn_bsd_init: [%d] ERR, state %lx data %lx\n", unit, (long)state, (long)data); + return 0; + } + + decomp = db->xmit ? 0 : 1; + + if (data->optlen != 1 || data->num != CI_BSD_COMPRESS + || (BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) + || (BSD_NBITS(data->options[0]) != db->maxbits) + || (decomp && db->lens == NULL)) { + printk(KERN_ERR "isdn_bsd: %d %d %d %d %lx\n", data->optlen, data->num, data->options[0], decomp, (unsigned long)db->lens); + return 0; + } + + if (decomp) + for (indx = LAST; indx >= 0; indx--) + db->lens[indx] = 1; + + indx = db->hsize; + while (indx-- != 0) { + db->dict[indx].codem1 = BADCODEM1; + db->dict[indx].cptr = 0; + } + + db->unit = unit; + db->mru = 0; + + db->debug = 1; + + bsd_reset(db, 0, 0, NULL, 0, NULL); + + return 1; +} + +/* + * Obtain pointers to the various structures in the compression tables + */ + +#define dict_ptrx(p, idx) &(p->dict[idx]) +#define lens_ptrx(p, idx) &(p->lens[idx]) + +#ifdef DEBUG +static unsigned short *lens_ptr(struct bsd_db *db, int idx) +{ + if ((unsigned int) idx > (unsigned int) db->maxmaxcode) { + printk(KERN_DEBUG "<9>ppp: lens_ptr(%d) > max\n", idx); + idx = 0; + } + return lens_ptrx(db, idx); +} + +static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx) +{ + if ((unsigned int) idx >= (unsigned int) db->hsize) { + printk(KERN_DEBUG "<9>ppp: dict_ptr(%d) > max\n", idx); + idx = 0; + } + return dict_ptrx(db, idx); +} + +#else +#define lens_ptr(db, idx) lens_ptrx(db, idx) +#define dict_ptr(db, idx) dict_ptrx(db, idx) +#endif + +/* + * compress a packet + */ +static int bsd_compress(void *state, struct sk_buff *skb_in, struct sk_buff *skb_out, int proto) +{ + struct bsd_db *db; + int hshift; + unsigned int max_ent; + unsigned int n_bits; + unsigned int bitno; + unsigned long accm; + int ent; + unsigned long fcode; + struct bsd_dict *dictp; + unsigned char c; + int hval, disp, ilen, mxcode; + unsigned char *rptr = skb_in->data; + int isize = skb_in->len; + +#define OUTPUT(ent) \ + { \ + bitno -= n_bits; \ + accm |= ((ent) << bitno); \ + do { \ + if (skb_out && skb_tailroom(skb_out) > 0) \ + skb_put_u8(skb_out, (u8)(accm >> 24)); \ + accm <<= 8; \ + bitno += 8; \ + } while (bitno <= 24); \ + } + + /* + * If the protocol is not in the range we're interested in, + * just return without compressing the packet. If it is, + * the protocol becomes the first byte to compress. + */ + printk(KERN_DEBUG "bsd_compress called with %x\n", proto); + + ent = proto; + if (proto < 0x21 || proto > 0xf9 || !(proto & 0x1)) + return 0; + + db = (struct bsd_db *) state; + hshift = db->hshift; + max_ent = db->max_ent; + n_bits = db->n_bits; + bitno = 32; + accm = 0; + mxcode = MAXCODE(n_bits); + + /* This is the PPP header information */ + if (skb_out && skb_tailroom(skb_out) >= 2) { + char *v = skb_put(skb_out, 2); + /* we only push our own data on the header, + AC,PC and protos is pushed by caller */ + v[0] = db->seqno >> 8; + v[1] = db->seqno; + } + + ilen = ++isize; /* This is off by one, but that is what is in draft! */ + + while (--ilen > 0) { + c = *rptr++; + fcode = BSD_KEY(ent, c); + hval = BSD_HASH(ent, c, hshift); + dictp = dict_ptr(db, hval); + + /* Validate and then check the entry. */ + if (dictp->codem1 >= max_ent) + goto nomatch; + + if (dictp->fcode == fcode) { + ent = dictp->codem1 + 1; + continue; /* found (prefix,suffix) */ + } + + /* continue probing until a match or invalid entry */ + disp = (hval == 0) ? 1 : hval; + + do { + hval += disp; + if (hval >= db->hsize) + hval -= db->hsize; + dictp = dict_ptr(db, hval); + if (dictp->codem1 >= max_ent) + goto nomatch; + } while (dictp->fcode != fcode); + + ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ + continue; + + nomatch: + OUTPUT(ent); /* output the prefix */ + + /* code -> hashtable */ + if (max_ent < db->maxmaxcode) { + struct bsd_dict *dictp2; + struct bsd_dict *dictp3; + int indx; + + /* expand code size if needed */ + if (max_ent >= mxcode) { + db->n_bits = ++n_bits; + mxcode = MAXCODE(n_bits); + } + + /* + * Invalidate old hash table entry using + * this code, and then take it over. + */ + dictp2 = dict_ptr(db, max_ent + 1); + indx = dictp2->cptr; + dictp3 = dict_ptr(db, indx); + + if (dictp3->codem1 == max_ent) + dictp3->codem1 = BADCODEM1; + + dictp2->cptr = hval; + dictp->codem1 = max_ent; + dictp->fcode = fcode; + db->max_ent = ++max_ent; + + if (db->lens) { + unsigned short *len1 = lens_ptr(db, max_ent); + unsigned short *len2 = lens_ptr(db, ent); + *len1 = *len2 + 1; + } + } + ent = c; + } + + OUTPUT(ent); /* output the last code */ + + if (skb_out) + db->bytes_out += skb_out->len; /* Do not count bytes from here */ + db->uncomp_bytes += isize; + db->in_count += isize; + ++db->uncomp_count; + ++db->seqno; + + if (bitno < 32) + ++db->bytes_out; /* must be set before calling bsd_check */ + + /* + * Generate the clear command if needed + */ + + if (bsd_check(db)) + OUTPUT(CLEAR); + + /* + * Pad dribble bits of last code with ones. + * Do not emit a completely useless byte of ones. + */ + if (bitno < 32 && skb_out && skb_tailroom(skb_out) > 0) + skb_put_u8(skb_out, + (unsigned char)((accm | (0xff << (bitno - 8))) >> 24)); + + /* + * Increase code size if we would have without the packet + * boundary because the decompressor will do so. + */ + if (max_ent >= mxcode && max_ent < db->maxmaxcode) + db->n_bits++; + + /* If output length is too large then this is an incompressible frame. */ + if (!skb_out || skb_out->len >= skb_in->len) { + ++db->incomp_count; + db->incomp_bytes += isize; + return 0; + } + + /* Count the number of compressed frames */ + ++db->comp_count; + db->comp_bytes += skb_out->len; + return skb_out->len; + +#undef OUTPUT +} + +/* + * Update the "BSD Compress" dictionary on the receiver for + * incompressible data by pretending to compress the incoming data. + */ +static void bsd_incomp(void *state, struct sk_buff *skb_in, int proto) +{ + bsd_compress(state, skb_in, NULL, proto); +} + +/* + * Decompress "BSD Compress". + */ +static int bsd_decompress(void *state, struct sk_buff *skb_in, struct sk_buff *skb_out, + struct isdn_ppp_resetparams *rsparm) +{ + struct bsd_db *db; + unsigned int max_ent; + unsigned long accm; + unsigned int bitno; /* 1st valid bit in accm */ + unsigned int n_bits; + unsigned int tgtbitno; /* bitno when we have a code */ + struct bsd_dict *dictp; + int seq; + unsigned int incode; + unsigned int oldcode; + unsigned int finchar; + unsigned char *p, *ibuf; + int ilen; + int codelen; + int extra; + + db = (struct bsd_db *) state; + max_ent = db->max_ent; + accm = 0; + bitno = 32; /* 1st valid bit in accm */ + n_bits = db->n_bits; + tgtbitno = 32 - n_bits; /* bitno when we have a code */ + + printk(KERN_DEBUG "bsd_decompress called\n"); + + if (!skb_in || !skb_out) { + printk(KERN_ERR "bsd_decompress called with NULL parameter\n"); + return DECOMP_ERROR; + } + + /* + * Get the sequence number. + */ + if ((p = skb_pull(skb_in, 2)) == NULL) { + return DECOMP_ERROR; + } + p -= 2; + seq = (p[0] << 8) + p[1]; + ilen = skb_in->len; + ibuf = skb_in->data; + + /* + * Check the sequence number and give up if it differs from + * the value we're expecting. + */ + if (seq != db->seqno) { + if (db->debug) { + printk(KERN_DEBUG "bsd_decomp%d: bad sequence # %d, expected %d\n", + db->unit, seq, db->seqno - 1); + } + return DECOMP_ERROR; + } + + ++db->seqno; + db->bytes_out += ilen; + + if (skb_tailroom(skb_out) > 0) + skb_put_u8(skb_out, 0); + else + return DECOMP_ERR_NOMEM; + + oldcode = CLEAR; + + /* + * Keep the checkpoint correctly so that incompressible packets + * clear the dictionary at the proper times. + */ + + for (;;) { + if (ilen-- <= 0) { + db->in_count += (skb_out->len - 1); /* don't count the header */ + break; + } + + /* + * Accumulate bytes until we have a complete code. + * Then get the next code, relying on the 32-bit, + * unsigned accm to mask the result. + */ + + bitno -= 8; + accm |= *ibuf++ << bitno; + if (tgtbitno < bitno) + continue; + + incode = accm >> tgtbitno; + accm <<= n_bits; + bitno += n_bits; + + /* + * The dictionary must only be cleared at the end of a packet. + */ + + if (incode == CLEAR) { + if (ilen > 0) { + if (db->debug) + printk(KERN_DEBUG "bsd_decomp%d: bad CLEAR\n", db->unit); + return DECOMP_FATALERROR; /* probably a bug */ + } + bsd_clear(db); + break; + } + + if ((incode > max_ent + 2) || (incode > db->maxmaxcode) + || (incode > max_ent && oldcode == CLEAR)) { + if (db->debug) { + printk(KERN_DEBUG "bsd_decomp%d: bad code 0x%x oldcode=0x%x ", + db->unit, incode, oldcode); + printk(KERN_DEBUG "max_ent=0x%x skb->Len=%d seqno=%d\n", + max_ent, skb_out->len, db->seqno); + } + return DECOMP_FATALERROR; /* probably a bug */ + } + + /* Special case for KwKwK string. */ + if (incode > max_ent) { + finchar = oldcode; + extra = 1; + } else { + finchar = incode; + extra = 0; + } + + codelen = *(lens_ptr(db, finchar)); + if (skb_tailroom(skb_out) < codelen + extra) { + if (db->debug) { + printk(KERN_DEBUG "bsd_decomp%d: ran out of mru\n", db->unit); +#ifdef DEBUG + printk(KERN_DEBUG " len=%d, finchar=0x%x, codelen=%d,skblen=%d\n", + ilen, finchar, codelen, skb_out->len); +#endif + } + return DECOMP_FATALERROR; + } + + /* + * Decode this code and install it in the decompressed buffer. + */ + + p = skb_put(skb_out, codelen); + p += codelen; + while (finchar > LAST) { + struct bsd_dict *dictp2 = dict_ptr(db, finchar); + + dictp = dict_ptr(db, dictp2->cptr); + +#ifdef DEBUG + if (--codelen <= 0 || dictp->codem1 != finchar - 1) { + if (codelen <= 0) { + printk(KERN_ERR "bsd_decomp%d: fell off end of chain ", db->unit); + printk(KERN_ERR "0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, dictp2->cptr, max_ent); + } else { + if (dictp->codem1 != finchar - 1) { + printk(KERN_ERR "bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", db->unit, incode, finchar); + printk(KERN_ERR "oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, dictp2->cptr, dictp->codem1); + } + } + return DECOMP_FATALERROR; + } +#endif + + { + u32 fcode = dictp->fcode; + *--p = (fcode >> 16) & 0xff; + finchar = fcode & 0xffff; + } + } + *--p = finchar; + +#ifdef DEBUG + if (--codelen != 0) + printk(KERN_ERR "bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", db->unit, codelen, incode, max_ent); +#endif + + if (extra) /* the KwKwK case again */ + skb_put_u8(skb_out, finchar); + + /* + * If not first code in a packet, and + * if not out of code space, then allocate a new code. + * + * Keep the hash table correct so it can be used + * with uncompressed packets. + */ + if (oldcode != CLEAR && max_ent < db->maxmaxcode) { + struct bsd_dict *dictp2, *dictp3; + u16 *lens1, *lens2; + unsigned long fcode; + int hval, disp, indx; + + fcode = BSD_KEY(oldcode, finchar); + hval = BSD_HASH(oldcode, finchar, db->hshift); + dictp = dict_ptr(db, hval); + + /* look for a free hash table entry */ + if (dictp->codem1 < max_ent) { + disp = (hval == 0) ? 1 : hval; + do { + hval += disp; + if (hval >= db->hsize) + hval -= db->hsize; + dictp = dict_ptr(db, hval); + } while (dictp->codem1 < max_ent); + } + + /* + * Invalidate previous hash table entry + * assigned this code, and then take it over + */ + + dictp2 = dict_ptr(db, max_ent + 1); + indx = dictp2->cptr; + dictp3 = dict_ptr(db, indx); + + if (dictp3->codem1 == max_ent) + dictp3->codem1 = BADCODEM1; + + dictp2->cptr = hval; + dictp->codem1 = max_ent; + dictp->fcode = fcode; + db->max_ent = ++max_ent; + + /* Update the length of this string. */ + lens1 = lens_ptr(db, max_ent); + lens2 = lens_ptr(db, oldcode); + *lens1 = *lens2 + 1; + + /* Expand code size if needed. */ + if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { + db->n_bits = ++n_bits; + tgtbitno = 32-n_bits; + } + } + oldcode = incode; + } + + ++db->comp_count; + ++db->uncomp_count; + db->comp_bytes += skb_in->len - BSD_OVHD; + db->uncomp_bytes += skb_out->len; + + if (bsd_check(db)) { + if (db->debug) + printk(KERN_DEBUG "bsd_decomp%d: peer should have cleared dictionary on %d\n", + db->unit, db->seqno - 1); + } + return skb_out->len; +} + +/************************************************************* + * Table of addresses for the BSD compression module + *************************************************************/ + +static struct isdn_ppp_compressor ippp_bsd_compress = { + .owner = THIS_MODULE, + .num = CI_BSD_COMPRESS, + .alloc = bsd_alloc, + .free = bsd_free, + .init = bsd_init, + .reset = bsd_reset, + .compress = bsd_compress, + .decompress = bsd_decompress, + .incomp = bsd_incomp, + .stat = bsd_stats, +}; + +/************************************************************* + * Module support routines + *************************************************************/ + +static int __init isdn_bsdcomp_init(void) +{ + int answer = isdn_ppp_register_compressor(&ippp_bsd_compress); + if (answer == 0) + printk(KERN_INFO "PPP BSD Compression module registered\n"); + return answer; +} + +static void __exit isdn_bsdcomp_exit(void) +{ + isdn_ppp_unregister_compressor(&ippp_bsd_compress); +} + +module_init(isdn_bsdcomp_init); +module_exit(isdn_bsdcomp_exit); |