usr/src/grub/grub-0.97/stage2/zfs_lzjb.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19 /*
  20  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  21  * Use is subject to license terms.
  22  */
  23
  24 #pragma ident   "%Z%%M% %I%     %E% SMI"
  25
  26 #include "fsys_zfs.h"
  27
  28 #define MATCH_BITS      6
  29 #define MATCH_MIN       3
  30 #define OFFSET_MASK     ((1 << (16 - MATCH_BITS)) - 1)
  31
  32
  33 /*ARGSUSED*/
  34 int
  35 lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len)
  36 {
  37         uchar_t *src = s_start;
  38         uchar_t *dst = d_start;
  39         uchar_t *d_end = (uchar_t *)d_start + d_len;
  40         uchar_t *cpy, copymap;
  41         int copymask = 1 << (NBBY - 1);
  42
  43         while (dst < d_end) {
  44                 if ((copymask <<= 1) == (1 << NBBY)) {
  45                         copymask = 1;
  46                         copymap = *src++;
  47                 }
  48                 if (copymap & copymask) {
  49                         int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
  50                         int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
  51                         src += 2;
  52                         if ((cpy = dst - offset) < (uchar_t *)d_start)
  53                                 return (-1);
  54                         while (--mlen >= 0 && dst < d_end)
  55                                 *dst++ = *cpy++;
  56                 } else {
  57                         *dst++ = *src++;
  58                 }
  59         }
  60         return (0);
  61 }