gen/rcz/rcz_decompress_file.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 #define REWIND  -1
  39
  40 extern int read(int fd, char *buf, int len);
  41
  42 static unsigned char *buf;
  43 static int buf_count;
  44
  45 #define BUF_SIZE 8192
  46
  47 static void
  48 alloc_buf(int fd)
  49 {
  50     buf = (unsigned char *)malloc(BUF_SIZE);
  51     buf_count = 0;
  52 }
  53
  54 static unsigned char
  55 get_byte(int fd)
  56 {
  57     static unsigned char *ptr;
  58
  59     if (buf_count == 0) {
  60         buf_count = read(fd, buf, BUF_SIZE);
  61         ptr = buf;
  62         if (buf_count <= 0)
  63             return 0xFF;
  64     }
  65     buf_count--;
  66     return *ptr++;
  67 }
  68
  69 static void
  70 free_buf(void)
  71 {
  72     buf_count = 0;
  73     free(buf);
  74 }
  75
  76
  77 int
  78 rcz_file_size(
  79     int in_fd
  80 )
  81 {
  82     unsigned int version, length;
  83
  84     alloc_buf(in_fd);
  85     b_lseek(in_fd, 0, 0);
  86     version = get_byte(in_fd);
  87     version = (version<<8) | (get_byte(in_fd));
  88     version = (version<<8) | (get_byte(in_fd));
  89     version = (version<<8) | (get_byte(in_fd));
  90
  91     if(version != METHOD_17_JUL_95) {
  92         return (-1);
  93 //      fprintf(stderr, "Incompatible version.\n");
  94 //      return(0);
  95     }
  96
  97     length = get_byte(in_fd);
  98     length = (length<<8) | (get_byte(in_fd));
  99     length = (length<<8) | (get_byte(in_fd));
 100     length = (length<<8) | (get_byte(in_fd));
 101     free_buf();
 102     return length;
 103 }
 104
 105 int
 106 rcz_decompress_file(
 107     int in_fd,
 108     unsigned char *out
 109 )
 110 /* Returns actual number of bytes emitted as decompressed stream 'out.'
 111    Note that the 'in' stream contains this byte count already.
 112
 113    Returns -1 if the input stream was not in compressed format.
 114  */
 115 {
 116     unsigned int c, j, k, jmatch, jabove;
 117     int length;
 118     unsigned int even_length, word, token, version;
 119     unsigned char *outorigin = out;
 120
 121     length = rcz_file_size(in_fd);
 122     if (length < 0)
 123         return length;
 124
 125     alloc_buf(in_fd);
 126     b_lseek(in_fd, 8, 0);
 127     for(c=0; c < QLEN; c++) que[c] = c;
 128     even_length = 2*(length/2);
 129     while((int)(out-outorigin) < even_length) {
 130         token = get_byte(in_fd);
 131         token = (token<<8) | (get_byte(in_fd));
 132         token = (token<<8) | (get_byte(in_fd));
 133         token = (token<<8) | (get_byte(in_fd));
 134         c = 1<<31;
 135         for(k = 0; k<32; k++) {
 136                 if(c & token) {
 137                       jmatch = get_byte(in_fd);
 138                       word = que[jmatch];
 139                   /* Next, dynamically process the queue for match. */
 140                       jabove = (F1*jmatch) >> 4;
 141                       for(j = jmatch; j > jabove; j--) {
 142                              que[j] = que[j-1];
 143                       }
 144                       que[jabove] = word;
 145                 } else {
 146                   /* Next, dynamically process the queue for unmatch. */
 147                     word = get_byte(in_fd);
 148                     word = (word << 8) | (get_byte(in_fd));
 149                     for(j=QLEN-1; j > ABOVE; j--) {
 150                         que[j] = que[j-1];
 151                     }
 152                     que[ABOVE] = word;
 153                 }
 154                 *out++ = (word >> 8) & 0xff;
 155                 *out++ = (word) & 0xff;
 156                 if((int)(out-outorigin) >= even_length) break;
 157                 c >>= 1;
 158         }
 159     }
 160     if(even_length != length) *out++ = get_byte(in_fd);
 161     free_buf();
 162     return(length);
 163 }