gen/rcz/rcz_decompress_mem.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26    Library: compressor for executable files.
  27
  28    R. E. Crandall, July 1995
  29
  30    Copyright 1995 NeXT Computer, Inc.
  31    All rights reserved.
  32
  33  */
  34
  35 #import "rcz_common.h"
  36
  37 static unsigned short que[QLEN];
  38
  39 unsigned int
  40 rcz_decompress_memory(unsigned char *in, unsigned char *out)
  41 /* Returns actual number of bytes emitted as decompressed stream 'out.'
  42    Note that the 'in' stream contains this byte count already.
  43
  44    Returns -1 if the input stream was not in compressed format.
  45  */
  46 {
  47     unsigned int c, j, k, jmatch, jabove;
  48     unsigned int length, even_length, word, token, version;
  49     unsigned char *outorigin = out;
  50
  51     version = *in++;
  52     version = (version<<8) | (*in++);
  53     version = (version<<8) | (*in++);
  54     version = (version<<8) | (*in++);
  55
  56     if(version != METHOD_17_JUL_95) {
  57         return (-1);
  58 //      fprintf(stderr, "Incompatible version.\n");
  59 //      return(0);
  60     }
  61
  62     length = *in++;
  63     length = (length<<8) | (*in++);
  64     length = (length<<8) | (*in++);
  65     length = (length<<8) | (*in++);
  66
  67     for(c=0; c < QLEN; c++) que[c] = c;
  68     even_length = 2*(length/2);
  69     while((int)(out-outorigin) < even_length) {
  70         token = *in++;
  71         token = (token<<8) | (*in++);
  72         token = (token<<8) | (*in++);
  73         token = (token<<8) | (*in++);
  74         c = 1<<31;
  75         for(k = 0; k<32; k++) {
  76                 if(c & token) {
  77                       jmatch = *in++;
  78                       word = que[jmatch];
  79                   /* Next, dynamically process the queue for match. */
  80                       jabove = (F1*jmatch) >> 4;
  81                       for(j = jmatch; j > jabove; j--) {
  82                              que[j] = que[j-1];
  83                       }
  84                       que[jabove] = word;
  85                 } else {
  86                   /* Next, dynamically process the queue for unmatch. */
  87                     word = *in++;
  88                     word = (word << 8) | (*in++);
  89                     for(j=QLEN-1; j > ABOVE; j--) {
  90                         que[j] = que[j-1];
  91                     }
  92                     que[ABOVE] = word;
  93                 }
  94                 *out++ = (word >> 8) & 0xff;
  95                 *out++ = (word) & 0xff;
  96                 if((int)(out-outorigin) >= even_length) break;
  97                 c >>= 1;
  98         }
  99     }
 100     if(even_length != length) *out++ = *in++;
 101     return(length);
 102 }