+/*
+ * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
+ *
+ * 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. 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_LICENSE_HEADER_END@
+ */
+/**************************************************************
+ 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
+
+**************************************************************/
+/*
+ * lzss.c - Package for decompressing lzss compressed objects
+ *
+ * Copyright (c) 2003 Apple Computer, Inc.
+ *
+ * DRI: Josh de Cesare
+ */
+
+#include <sl.h>
+
+#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 */
+
+int
+decompress_lzss(u_int8_t *dst, 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 *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;
+ 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;
+ text_buf[r++] = c;
+ r &= (N - 1);
+ }
+ }
+ }
+
+ return dst - dststart;
+}
projects / apple / bootx.git / commitdiff
