--- /dev/null
+/*
+ * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ */
+#include <string.h>
+#include <libkern/mkext.h>
+
+#define BASE 65521L /* largest prime smaller than 65536 */
+#define NMAX 5000
+// NMAX (was 5521) the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
+
+#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
+#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
+#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
+#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
+#define DO16(buf) DO8(buf,0); DO8(buf,8);
+
+u_int32_t
+mkext_adler32(uint8_t *buf, int32_t len)
+{
+ unsigned long s1 = 1; // adler & 0xffff;
+ unsigned long s2 = 0; // (adler >> 16) & 0xffff;
+ int k;
+
+ while (len > 0) {
+ k = len < NMAX ? len : NMAX;
+ len -= k;
+ while (k >= 16) {
+ DO16(buf);
+ buf += 16;
+ k -= 16;
+ }
+ if (k != 0) do {
+ s1 += *buf++;
+ s2 += s1;
+ } while (--k);
+ s1 %= BASE;
+ s2 %= BASE;
+ }
+ return (s2 << 16) | s1;
+}
+
+
+/**************************************************************
+ LZSS.C -- A Data Compression Program
+***************************************************************
+ 4/6/1989 Haruhiko Okumura
+ Use, distribute, and modify this program freely.
+ Please send me your improved versions.
+ PC-VAN SCIENCE
+ NIFTY-Serve PAF01022
+ CompuServe 74050,1022
+
+**************************************************************/
+
+#define N 4096 /* size of ring buffer - must be power of 2 */
+#define F 18 /* upper limit for match_length */
+#define THRESHOLD 2 /* encode string into position and length
+ if match_length is greater than this */
+#define NIL N /* index for root of binary search trees */
+
+struct encode_state {
+ /*
+ * left & right children & parent. These constitute binary search trees.
+ */
+ int lchild[N + 1], rchild[N + 257], parent[N + 1];
+
+ /* ring buffer of size N, with extra F-1 bytes to aid string comparison */
+ u_int8_t text_buf[N + F - 1];
+
+ /*
+ * match_length of longest match.
+ * These are set by the insert_node() procedure.
+ */
+ int match_position, match_length;
+};
+
+
+int
+decompress_lzss(u_int8_t *dst, u_int32_t dstlen, u_int8_t *src, u_int32_t srclen)
+{
+ /* ring buffer of size N, with extra F-1 bytes to aid string comparison */
+ u_int8_t text_buf[N + F - 1];
+ u_int8_t *dststart = dst;
+ u_int8_t *dstend = dst + dstlen;
+ u_int8_t *srcend = src + srclen;
+ int i, j, k, r, c;
+ unsigned int flags;
+
+ dst = dststart;
+ srcend = src + srclen;
+ for (i = 0; i < N - F; i++)
+ text_buf[i] = ' ';
+ r = N - F;
+ flags = 0;
+ for ( ; ; ) {
+ if (((flags >>= 1) & 0x100) == 0) {
+ if (src < srcend) c = *src++; else break;
+ flags = c | 0xFF00; /* uses higher byte cleverly */
+ } /* to count eight */
+ if (flags & 1) {
+ if (src < srcend) c = *src++; else break;
+ *dst++ = c;
+ if (dst >= dstend) {
+ goto finish;
+ }
+ text_buf[r++] = c;
+ r &= (N - 1);
+ } else {
+ if (src < srcend) i = *src++; else break;
+ if (src < srcend) j = *src++; else break;
+ i |= ((j & 0xF0) << 4);
+ j = (j & 0x0F) + THRESHOLD;
+ for (k = 0; k <= j; k++) {
+ c = text_buf[(i + k) & (N - 1)];
+ *dst++ = c;
+ if (dst >= dstend) {
+ goto finish;
+ }
+ text_buf[r++] = c;
+ r &= (N - 1);
+ }
+ }
+ }
+finish:
+ return dst - dststart;
+}
+
+#if !KERNEL
+
+/*
+ * initialize state, mostly the trees
+ *
+ * For i = 0 to N - 1, rchild[i] and lchild[i] will be the right and left
+ * children of node i. These nodes need not be initialized. Also, parent[i]
+ * is the parent of node i. These are initialized to NIL (= N), which stands
+ * for 'not used.' For i = 0 to 255, rchild[N + i + 1] is the root of the
+ * tree for strings that begin with character i. These are initialized to NIL.
+ * Note there are 256 trees. */
+static void init_state(struct encode_state *sp)
+{
+ int i;
+
+ bzero(sp, sizeof(*sp));
+
+ for (i = 0; i < N - F; i++)
+ sp->text_buf[i] = ' ';
+ for (i = N + 1; i <= N + 256; i++)
+ sp->rchild[i] = NIL;
+ for (i = 0; i < N; i++)
+ sp->parent[i] = NIL;
+}
+
+/*
+ * Inserts string of length F, text_buf[r..r+F-1], into one of the trees
+ * (text_buf[r]'th tree) and returns the longest-match position and length
+ * via the global variables match_position and match_length.
+ * If match_length = F, then removes the old node in favor of the new one,
+ * because the old one will be deleted sooner. Note r plays double role,
+ * as tree node and position in buffer.
+ */
+static void insert_node(struct encode_state *sp, int r)
+{
+ int i, p, cmp;
+ u_int8_t *key;
+
+ cmp = 1;
+ key = &sp->text_buf[r];
+ p = N + 1 + key[0];
+ sp->rchild[r] = sp->lchild[r] = NIL;
+ sp->match_length = 0;
+ for ( ; ; ) {
+ if (cmp >= 0) {
+ if (sp->rchild[p] != NIL)
+ p = sp->rchild[p];
+ else {
+ sp->rchild[p] = r;
+ sp->parent[r] = p;
+ return;
+ }
+ } else {
+ if (sp->lchild[p] != NIL)
+ p = sp->lchild[p];
+ else {
+ sp->lchild[p] = r;
+ sp->parent[r] = p;
+ return;
+ }
+ }
+ for (i = 1; i < F; i++) {
+ if ((cmp = key[i] - sp->text_buf[p + i]) != 0)
+ break;
+ }
+ if (i > sp->match_length) {
+ sp->match_position = p;
+ if ((sp->match_length = i) >= F)
+ break;
+ }
+ }
+ sp->parent[r] = sp->parent[p];
+ sp->lchild[r] = sp->lchild[p];
+ sp->rchild[r] = sp->rchild[p];
+ sp->parent[sp->lchild[p]] = r;
+ sp->parent[sp->rchild[p]] = r;
+ if (sp->rchild[sp->parent[p]] == p)
+ sp->rchild[sp->parent[p]] = r;
+ else
+ sp->lchild[sp->parent[p]] = r;
+ sp->parent[p] = NIL; /* remove p */
+}
+
+/* deletes node p from tree */
+static void delete_node(struct encode_state *sp, int p)
+{
+ int q;
+
+ if (sp->parent[p] == NIL)
+ return; /* not in tree */
+ if (sp->rchild[p] == NIL)
+ q = sp->lchild[p];
+ else if (sp->lchild[p] == NIL)
+ q = sp->rchild[p];
+ else {
+ q = sp->lchild[p];
+ if (sp->rchild[q] != NIL) {
+ do {
+ q = sp->rchild[q];
+ } while (sp->rchild[q] != NIL);
+ sp->rchild[sp->parent[q]] = sp->lchild[q];
+ sp->parent[sp->lchild[q]] = sp->parent[q];
+ sp->lchild[q] = sp->lchild[p];
+ sp->parent[sp->lchild[p]] = q;
+ }
+ sp->rchild[q] = sp->rchild[p];
+ sp->parent[sp->rchild[p]] = q;
+ }
+ sp->parent[q] = sp->parent[p];
+ if (sp->rchild[sp->parent[p]] == p)
+ sp->rchild[sp->parent[p]] = q;
+ else
+ sp->lchild[sp->parent[p]] = q;
+ sp->parent[p] = NIL;
+}
+
+#endif /* !KERNEL */
+
projects / apple / xnu.git / blobdiff