1/*
2 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28#include <stdint.h> // For uintptr_t.
29#include <string.h>
30#include <libkern/mkext.h>
31
32
33#define BASE 65521L /* largest prime smaller than 65536 */
34#define NMAX 5552  // the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
35
36#define DO1(buf,i)  {s1 += buf[i]; s2 += s1;}
37#define DO2(buf,i)  DO1(buf,i); DO1(buf,i+1);
38#define DO4(buf,i)  DO2(buf,i); DO2(buf,i+2);
39#define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
40#define DO16(buf)   DO8(buf,0); DO8(buf,8);
41
42u_int32_t
43mkext_adler32(uint8_t *buf, int32_t len)
44{
45    unsigned long s1 = 1; // adler & 0xffff;
46    unsigned long s2 = 0; // (adler >> 16) & 0xffff;
47    int k;
48
49#if defined _ARM_ARCH_6
50
51	/* align buf to 16-byte boundary */
52    while ((((uintptr_t)buf)&15)&&(len>0)) { /* not on a 16-byte boundary */
53        len--;
54        s1 += *buf++;
55        s2 += s1;
56        if (s1 >= BASE) s1 -= BASE;
57    }
58	s2 %= BASE;
59
60	if (len>=16) {
61		return adler32_vec(s1, s2, buf, len);
62	}
63
64#endif
65
66    while (len > 0) {
67        k = len < NMAX ? len : NMAX;
68        len -= k;
69        while (k >= 16) {
70            DO16(buf);
71	    buf += 16;
72            k -= 16;
73        }
74        if (k != 0) do {
75            s1 += *buf++;
76	    s2 += s1;
77        } while (--k);
78        s1 %= BASE;
79        s2 %= BASE;
80    }
81    return (s2 << 16) | s1;
82}
83
84
85/**************************************************************
86 LZSS.C -- A Data Compression Program
87***************************************************************
88    4/6/1989 Haruhiko Okumura
89    Use, distribute, and modify this program freely.
90    Please send me your improved versions.
91        PC-VAN      SCIENCE
92        NIFTY-Serve PAF01022
93        CompuServe  74050,1022
94
95**************************************************************/
96
97#define N         4096  /* size of ring buffer - must be power of 2 */
98#define F         18    /* upper limit for match_length */
99#define THRESHOLD 2     /* encode string into position and length
100                           if match_length is greater than this */
101#define NIL       N     /* index for root of binary search trees */
102
103struct encode_state {
104    /*
105     * left & right children & parent. These constitute binary search trees.
106     */
107    int lchild[N + 1], rchild[N + 257], parent[N + 1];
108
109    /* ring buffer of size N, with extra F-1 bytes to aid string comparison */
110    u_int8_t text_buf[N + F - 1];
111
112    /*
113     * match_length of longest match.
114     * These are set by the insert_node() procedure.
115     */
116    int match_position, match_length;
117};
118
119
120int
121decompress_lzss(u_int8_t *dst, u_int32_t dstlen, u_int8_t *src, u_int32_t srclen)
122{
123    /* ring buffer of size N, with extra F-1 bytes to aid string comparison */
124    u_int8_t text_buf[N + F - 1];
125    u_int8_t *dststart = dst;
126	u_int8_t *dstend = dst + dstlen;
127    u_int8_t *srcend = src + srclen;
128    int  i, j, k, r, c;
129    unsigned int flags;
130
131    dst = dststart;
132    srcend = src + srclen;
133    for (i = 0; i < N - F; i++)
134        text_buf[i] = ' ';
135    r = N - F;
136    flags = 0;
137    for ( ; ; ) {
138        if (((flags >>= 1) & 0x100) == 0) {
139            if (src < srcend) c = *src++; else break;
140            flags = c | 0xFF00;  /* uses higher byte cleverly */
141        }   /* to count eight */
142        if (flags & 1) {
143            if (src < srcend) c = *src++; else break;
144            *dst++ = c;
145			if (dst >= dstend) {
146				goto finish;
147			}
148            text_buf[r++] = c;
149            r &= (N - 1);
150        } else {
151            if (src < srcend) i = *src++; else break;
152            if (src < srcend) j = *src++; else break;
153            i |= ((j & 0xF0) << 4);
154            j  =  (j & 0x0F) + THRESHOLD;
155            for (k = 0; k <= j; k++) {
156                c = text_buf[(i + k) & (N - 1)];
157                *dst++ = c;
158				if (dst >= dstend) {
159					goto finish;
160				}
161                text_buf[r++] = c;
162                r &= (N - 1);
163            }
164        }
165    }
166finish:
167    return dst - dststart;
168}
169
170#if !KERNEL
171
172/*
173 * initialize state, mostly the trees
174 *
175 * For i = 0 to N - 1, rchild[i] and lchild[i] will be the right and left
176 * children of node i.  These nodes need not be initialized.  Also, parent[i]
177 * is the parent of node i.  These are initialized to NIL (= N), which stands
178 * for 'not used.'  For i = 0 to 255, rchild[N + i + 1] is the root of the
179 * tree for strings that begin with character i.  These are initialized to NIL.
180 * Note there are 256 trees. */
181static void init_state(struct encode_state *sp)
182{
183    int  i;
184
185    bzero(sp, sizeof(*sp));
186
187    for (i = 0; i < N - F; i++)
188        sp->text_buf[i] = ' ';
189    for (i = N + 1; i <= N + 256; i++)
190        sp->rchild[i] = NIL;
191    for (i = 0; i < N; i++)
192        sp->parent[i] = NIL;
193}
194
195/*
196 * Inserts string of length F, text_buf[r..r+F-1], into one of the trees
197 * (text_buf[r]'th tree) and returns the longest-match position and length
198 * via the global variables match_position and match_length.
199 * If match_length = F, then removes the old node in favor of the new one,
200 * because the old one will be deleted sooner. Note r plays double role,
201 * as tree node and position in buffer.
202 */
203static void insert_node(struct encode_state *sp, int r)
204{
205    int  i, p, cmp;
206    u_int8_t  *key;
207
208    cmp = 1;
209    key = &sp->text_buf[r];
210    p = N + 1 + key[0];
211    sp->rchild[r] = sp->lchild[r] = NIL;
212    sp->match_length = 0;
213    for ( ; ; ) {
214        if (cmp >= 0) {
215            if (sp->rchild[p] != NIL)
216                p = sp->rchild[p];
217            else {
218                sp->rchild[p] = r;
219                sp->parent[r] = p;
220                return;
221            }
222        } else {
223            if (sp->lchild[p] != NIL)
224                p = sp->lchild[p];
225            else {
226                sp->lchild[p] = r;
227                sp->parent[r] = p;
228                return;
229            }
230        }
231        for (i = 1; i < F; i++) {
232            if ((cmp = key[i] - sp->text_buf[p + i]) != 0)
233                break;
234        }
235        if (i > sp->match_length) {
236            sp->match_position = p;
237            if ((sp->match_length = i) >= F)
238                break;
239        }
240    }
241    sp->parent[r] = sp->parent[p];
242    sp->lchild[r] = sp->lchild[p];
243    sp->rchild[r] = sp->rchild[p];
244    sp->parent[sp->lchild[p]] = r;
245    sp->parent[sp->rchild[p]] = r;
246    if (sp->rchild[sp->parent[p]] == p)
247        sp->rchild[sp->parent[p]] = r;
248    else
249        sp->lchild[sp->parent[p]] = r;
250    sp->parent[p] = NIL;  /* remove p */
251}
252
253/* deletes node p from tree */
254static void delete_node(struct encode_state *sp, int p)
255{
256    int  q;
257
258    if (sp->parent[p] == NIL)
259        return;  /* not in tree */
260    if (sp->rchild[p] == NIL)
261        q = sp->lchild[p];
262    else if (sp->lchild[p] == NIL)
263        q = sp->rchild[p];
264    else {
265        q = sp->lchild[p];
266        if (sp->rchild[q] != NIL) {
267            do {
268                q = sp->rchild[q];
269            } while (sp->rchild[q] != NIL);
270            sp->rchild[sp->parent[q]] = sp->lchild[q];
271            sp->parent[sp->lchild[q]] = sp->parent[q];
272            sp->lchild[q] = sp->lchild[p];
273            sp->parent[sp->lchild[p]] = q;
274        }
275        sp->rchild[q] = sp->rchild[p];
276        sp->parent[sp->rchild[p]] = q;
277    }
278    sp->parent[q] = sp->parent[p];
279    if (sp->rchild[sp->parent[p]] == p)
280        sp->rchild[sp->parent[p]] = q;
281    else
282        sp->lchild[sp->parent[p]] = q;
283    sp->parent[p] = NIL;
284}
285
286#endif /* !KERNEL */
287
288