release/src-rt-6.x/linux/linux-2.6/scripts/squashfs/read_fs.h

   1 /*
   2  * macros to convert each packed bitfield structure from little endian to big
   3  * endian and vice versa.  These are needed when creating a filesystem on a
   4  * machine with different byte ordering to the target architecture.
   5  *
   6  * Copyright (c) 2002, 2003, 2004, 2005, 2006
   7  * Phillip Lougher <phillip@lougher.org.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; either version 2,
  12  * or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22  *
  23  * mksquashfs.h
  24  *
  25  */
  26
  27 /*
  28  * macros used to swap each structure entry, taking into account
  29  * bitfields and different bitfield placing conventions on differing architectures
  30  */
  31 #if __BYTE_ORDER == __BIG_ENDIAN
  32         /* convert from big endian to little endian */
  33 #define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, tbits, b_pos)
  34 #else
  35         /* convert from little endian to big endian */
  36 #define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, tbits, 64 - tbits - b_pos)
  37 #endif
  38
  39 #define _SQUASHFS_SWAP(value, p, pos, tbits, SHIFT) {\
  40         int bits;\
  41         int b_pos = pos % 8;\
  42         unsigned long long val = 0;\
  43         unsigned char *s = (unsigned char *)p + (pos / 8);\
  44         unsigned char *d = ((unsigned char *) &val) + 7;\
  45         for(bits = 0; bits < (tbits + b_pos); bits += 8) \
  46                 *d-- = *s++;\
  47         value = (val >> (SHIFT))/* & ((1 << tbits) - 1)*/;\
  48 }
  49 #define SQUASHFS_MEMSET(s, d, n)        memset(s, 0, n);