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  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25    Library: compressor for executable files.
  26
  27    R. E. Crandall, July 1995
  28
  29    Copyright 1995 NeXT Computer, Inc.
  30    All rights reserved.
  31
  32  */
  33
  34 #import "rcz_common.h"
  35
  36 static unsigned short que[QLEN];
  37
  38 unsigned int
  39 rcz_decompress_memory(unsigned char *in, unsigned char *out)
  40 /* Returns actual number of bytes emitted as decompressed stream 'out.'
  41    Note that the 'in' stream contains this byte count already.
  42
  43    Returns -1 if the input stream was not in compressed format.
  44  */
  45 {
  46     unsigned int c, j, k, jmatch, jabove;
  47     unsigned int length, even_length, word, token, version;
  48     unsigned char *outorigin = out;
  49
  50     version = *in++;
  51     version = (version<<8) | (*in++);
  52     version = (version<<8) | (*in++);
  53     version = (version<<8) | (*in++);
  54
  55     if(version != METHOD_17_JUL_95) {
  56         return (-1);
  57 //      fprintf(stderr, "Incompatible version.\n");
  58 //      return(0);
  59     }
  60
  61     length = *in++;
  62     length = (length<<8) | (*in++);
  63     length = (length<<8) | (*in++);
  64     length = (length<<8) | (*in++);
  65
  66     for(c=0; c < QLEN; c++) que[c] = c;
  67     even_length = 2*(length/2);
  68     while((int)(out-outorigin) < even_length) {
  69         token = *in++;
  70         token = (token<<8) | (*in++);
  71         token = (token<<8) | (*in++);
  72         token = (token<<8) | (*in++);
  73         c = 1<<31;
  74         for(k = 0; k<32; k++) {
  75                 if(c & token) {
  76                       jmatch = *in++;
  77                       word = que[jmatch];
  78                   /* Next, dynamically process the queue for match. */
  79                       jabove = (F1*jmatch) >> 4;
  80                       for(j = jmatch; j > jabove; j--) {
  81                              que[j] = que[j-1];
  82                       }
  83                       que[jabove] = word;
  84                 } else {
  85                   /* Next, dynamically process the queue for unmatch. */
  86                     word = *in++;
  87                     word = (word << 8) | (*in++);
  88                     for(j=QLEN-1; j > ABOVE; j--) {
  89                         que[j] = que[j-1];
  90                     }
  91                     que[ABOVE] = word;
  92                 }
  93                 *out++ = (word >> 8) & 0xff;
  94                 *out++ = (word) & 0xff;
  95                 if((int)(out-outorigin) >= even_length) break;
  96                 c >>= 1;
  97         }
  98     }
  99     if(even_length != length) *out++ = *in++;
 100     return(length);
 101 }